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Chochua S, Metcalf B, Li Z, Mathis S, Tran T, Rivers J, Fleming-Dutra KE, Li Y, McGee L, Beall B. Invasive Group A Streptococcal Penicillin Binding Protein 2× Variants Associated with Reduced Susceptibility to β-Lactam Antibiotics in the United States, 2015-2021. Antimicrob Agents Chemother 2022; 66:e0080222. [PMID: 35969070 PMCID: PMC9487518 DOI: 10.1128/aac.00802-22] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 07/18/2022] [Indexed: 11/20/2022] Open
Abstract
All known group A streptococci [GAS] are susceptible to β-lactam antibiotics. We recently identified an invasive GAS (iGAS) variant (emm43.4/PBP2x-T553K) with unusually high minimum inhibitory concentrations (MICs) for ampicillin and amoxicillin, although clinically susceptible to β-lactams. We aimed to quantitate PBP2x variants, small changes in β-lactam MICs, and lineages within contemporary population-based iGAS. PBP2x substitutions were comprehensively identified among 13,727 iGAS recovered during 2015-2021, in the USA. Isolates were subjected to antimicrobial susceptibility testing employing low range agar diffusion and PBP2x variants were subjected to phylogenetic analyses. Fifty-five variants were defined based upon substitutions within an assigned PBP2x transpeptidase domain. Twenty-nine of these variants, representing 338/13,727 (2.5%) isolates and 16 emm types, exhibited slightly elevated β-lactam MICs, none of which were above clinical breakpoints. The emm43.4/PBP2x-T553K variant, comprised of two isolates, displayed the most significant phenotype (ampicillin MIC 0.25 μg/ml) and harbored missense mutations within 3 non-PBP genes with known involvement in antibiotic efflux, membrane insertion of PBP2x, and peptidoglycan remodeling. The proportion of all PBP2x variants with elevated MICs remained stable throughout 2015-2021 (<3.0%). The predominant lineage (emm4/PBP2x-M593T/ermT) was resistant to macrolides/lincosamides and comprised 129/340 (37.9%) of isolates with elevated β-lactam MICs. Continuing β-lactam selective pressure is likely to have selected PBP2x variants that had escaped scrutiny due to MICs that remain below clinical cutoffs. Higher MICs exhibited by emm43.4/PBP2x-T553K are probably rare due to the requirement of additional mutations. Although elevated β-lactam MICs remain uncommon, emm43.4/PBP2x-T553K and emm4/PBP2x-M593T/ermT lineages indicate that antibiotic stewardship and strain monitoring is necessary.
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Affiliation(s)
- Sopio Chochua
- Respiratory Disease Branch, National Center for Immunizations and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Benjamin Metcalf
- Respiratory Disease Branch, National Center for Immunizations and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Zhongya Li
- ASRT Inc., Contractor to Respiratory Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Saundra Mathis
- ASRT Inc., Contractor to Respiratory Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Theresa Tran
- ASRT Inc., Contractor to Respiratory Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Joy Rivers
- Respiratory Disease Branch, National Center for Immunizations and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Katherine E. Fleming-Dutra
- Respiratory Disease Branch, National Center for Immunizations and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Yuan Li
- Respiratory Disease Branch, National Center for Immunizations and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Lesley McGee
- Respiratory Disease Branch, National Center for Immunizations and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Bernard Beall
- Respiratory Disease Branch, National Center for Immunizations and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
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2
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Zhou M, Wang L, Wang Z, Kudinha T, Wang Y, Xu Y, Liu Z. Molecular Characterization of Penicillin-Binding Protein2x, 2b and 1a of Streptococcus pneumoniae Causing Invasive Pneumococcal Diseases in China: A Multicenter Study. Front Microbiol 2022; 13:838790. [PMID: 35300486 PMCID: PMC8921733 DOI: 10.3389/fmicb.2022.838790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Accepted: 01/19/2022] [Indexed: 11/26/2022] Open
Abstract
Streptococcus pneumoniae is a common human pathogen that can cause severe invasive pneumococcal diseases (IPDs). Penicillin-binding proteins (PBPs) are the targets for β-lactam antibiotics (BLAs), which are the common empirical drugs for treatment of pneumococcal infection. This study investigated the serotype distribution and antibiotic resistance patterns of S. pneumoniae strains causing IPD in China, including exploring the association between penicillin (PEN) susceptibility and PBPs variations. A total of 300 invasive S. pneumoniae isolates were collected from 27 teaching hospitals in China (2010-2015). Serotypes were determined by Quellung reaction. Serotypes 23F and 19F were the commonest serotypes in isolates from cerebrospinal fluid (CSF), whilst serotypes 19A and 23F were most commonly seen in non-CSF specimens. Among the 300 invasive S. pneumoniae strains, only one strain (serotype 6A, MIC = 0.25 μg/ml) with PEN MIC value ≤ 0.25 μg/ml did not have any substitutions in the PBPs active sites. All the strains with PEN MIC value ≥ 0.5 μg/ml had different substitutions within PBPs active sites. Substitutions in PBP2b and PBP2x active sites were common in low-level penicillin-resistant S. pneumoniae (PRSP) strains (MIC = 0.5 μg/ml), with or without PBP1a substitution, while all strains with PEN MIC ≥ 1 μg/ml had substitutions in PBP1a active sites, accompanied by PBP2b and PBP2x active site substitutions. Based on the three PBPs substitution combinations, a high degree of diversity was observed amongst the isolates. This study provides some new insights for understanding the serology and antibiotic resistance dynamics of S. pneumoniae causing IPD in China. However, further genomic studies are needed to facilitate a comprehensive understanding of antibiotic resistance mechanisms of S. pneumoniae.
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Affiliation(s)
- Menglan Zhou
- Department of Clinical Laboratory, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.,Beijing Key Laboratory for Mechanisms Research and Precision Diagnosis of Invasive Fungal Diseases, Beijing, China
| | - Lulu Wang
- Nanjing Hospital of Chinese Medicine Affiliated to Nanjing University of Chinese Medicine, Nanjing, China
| | - Ziran Wang
- Department of Clinical Laboratory, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.,Beijing Key Laboratory for Mechanisms Research and Precision Diagnosis of Invasive Fungal Diseases, Beijing, China
| | - Timothy Kudinha
- School of Biomedical Sciences, Charles Sturt University, Orange, NSW, Australia.,NSW Health Pathology, Regional and Rural, Orange Hospital, Orange, NSW, Australia
| | - Yao Wang
- Department of Clinical Laboratory, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.,Beijing Key Laboratory for Mechanisms Research and Precision Diagnosis of Invasive Fungal Diseases, Beijing, China
| | - Yingchun Xu
- Department of Clinical Laboratory, State Key Laboratory of Complex Severe and Rare Diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.,Beijing Key Laboratory for Mechanisms Research and Precision Diagnosis of Invasive Fungal Diseases, Beijing, China
| | - Zhengyin Liu
- Department of Infectious Disease, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences, Beijing, China
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3
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Kalizang'oma A, Chaguza C, Gori A, Davison C, Beleza S, Antonio M, Beall B, Goldblatt D, Kwambana-Adams B, Bentley SD, Heyderman RS. Streptococcus pneumoniae serotypes that frequently colonise the human nasopharynx are common recipients of penicillin-binding protein gene fragments from Streptococcus mitis. Microb Genom 2021; 7. [PMID: 34550067 PMCID: PMC8715442 DOI: 10.1099/mgen.0.000622] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Streptococcus pneumoniae is an important global pathogen that causes bacterial pneumonia, sepsis and meningitis. Beta-lactam antibiotics are the first-line treatment for pneumococcal disease, however, their effectiveness is hampered by beta-lactam resistance facilitated by horizontal genetic transfer (HGT) with closely related species. Although interspecies HGT is known to occur among the species of the genus Streptococcus, the rates and effects of HGT between Streptococcus pneumoniae and its close relatives involving the penicillin binding protein (pbp) genes remain poorly understood. Here we applied the fastGEAR tool to investigate interspecies HGT in pbp genes using a global collection of whole-genome sequences of Streptococcus mitis, Streptococcus oralis and S. pneumoniae. With these data, we established that pneumococcal serotypes 6A, 13, 14, 16F, 19A, 19F, 23F and 35B were the highest-ranking serotypes with acquired pbp fragments. S. mitis was a more frequent pneumococcal donor of pbp fragments and a source of higher pbp nucleotide diversity when compared with S. oralis. Pneumococci that acquired pbp fragments were associated with a higher minimum inhibitory concentration (MIC) for penicillin compared with pneumococci without acquired fragments. Together these data indicate that S. mitis contributes to reduced β-lactam susceptibility among commonly carried pneumococcal serotypes that are associated with long carriage duration and high recombination frequencies. As pneumococcal vaccine programmes mature, placing increasing pressure on the pneumococcal population structure, it will be important to monitor the influence of antimicrobial resistance HGT from commensal streptococci such as S. mitis.
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Affiliation(s)
- Akuzike Kalizang'oma
- NIHR Global Health Research Unit on Mucosal Pathogens, Division of Infection & Immunity, University College London, London, UK
| | - Chrispin Chaguza
- Parasites and Microbes, Wellcome Sanger Institute, Hinxton, UK.,Darwin College, University of Cambridge, Silver Street, Cambridge, UK.,Department of Clinical Infection, Microbiology and Immunology, Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, Liverpool, UK
| | - Andrea Gori
- NIHR Global Health Research Unit on Mucosal Pathogens, Division of Infection & Immunity, University College London, London, UK
| | - Charlotte Davison
- Department of Genetics and Genome Biology, University of Leicester, Leicester, UK
| | - Sandra Beleza
- Department of Genetics and Genome Biology, University of Leicester, Leicester, UK
| | - Martin Antonio
- Medical Research Council Unit The Gambia at London School of Hygiene & Tropical Medicine, World Health Organization, Collaborating Centre for New Vaccines Surveillance, Banjul, Gambia
| | - Bernard Beall
- Centers for Disease Control and Prevention, National Center for Immunization and Respiratory Diseases, Division of Bacterial Diseases, Atlanta, GA, USA
| | - David Goldblatt
- University College London, Great Ormond Street Institute of Child Health, London, UK
| | - Brenda Kwambana-Adams
- NIHR Global Health Research Unit on Mucosal Pathogens, Division of Infection & Immunity, University College London, London, UK
| | | | - Robert S Heyderman
- NIHR Global Health Research Unit on Mucosal Pathogens, Division of Infection & Immunity, University College London, London, UK
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4
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Peters K, Schweizer I, Hakenbeck R, Denapaite D. New Insights into Beta-Lactam Resistance of Streptococcus pneumoniae: Serine Protease HtrA Degrades Altered Penicillin-Binding Protein 2x. Microorganisms 2021; 9:microorganisms9081685. [PMID: 34442764 PMCID: PMC8400419 DOI: 10.3390/microorganisms9081685] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2021] [Revised: 08/02/2021] [Accepted: 08/04/2021] [Indexed: 11/18/2022] Open
Abstract
Reduced amounts of the essential penicillin-binding protein 2x (PBP2x) were detected in two cefotaxime-resistant Streptococcus pneumoniae laboratory mutants C405 and C606. These mutants contain two or four mutations in the penicillin-binding domain of PBP2x, respectively. The transcription of the pbp2x gene was not affected in both mutants; thus, the reduced PBP2x amounts were likely due to post-transcriptional regulation. The mutants carry a mutation in the histidine protein kinase gene ciaH, resulting in enhanced gene expression mediated by the cognate response regulator CiaR. Deletion of htrA, encoding a serine protease regulated by CiaR, or inactivation of HtrA proteolytic activity showed that HtrA is indeed responsible for PBP2x degradation in both mutants, and that this affects β-lactam resistance. Depletion of the PBP2xC405 in different genetic backgrounds confirmed that HtrA degrades PBP2xC405. A GFP-PBP2xC405 fusion protein still localized at the septum in the absence of HtrA. The complementation studies in HtrA deletion strains showed that HtrA can be overexpressed in pneumococcal cells to specific levels, depending on the genetic background. Quantitative Western blotting revealed that the PBP2x amount in C405 strain was less than 20% compared to parental strain, suggesting that PBP2x is an abundant protein in S. pneumoniae R6 strain.
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5
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Park M, Sutherland JB, Rafii F. β-Lactam resistance development affects binding of penicillin-binding proteins (PBPs) of Clostridium perfringens to the fluorescent penicillin, BOCILLIN FL. Anaerobe 2020; 62:102179. [PMID: 32088319 DOI: 10.1016/j.anaerobe.2020.102179] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 02/18/2020] [Accepted: 02/19/2020] [Indexed: 01/11/2023]
Abstract
Alteration in the binding of bacterial penicillin-binding proteins (PBPs) to β-lactams is important in the development of drug resistance. The PBPs of wild type Clostridium perfringens ATCC 13124 and three β-lactam-resistant mutants were compared for the ability to bind to a fluorescent penicillin, BOCILLIN FL. The binding of the high molecular weight protein PBP1, a transpeptidase, to BOCILLIN FL was reduced in all of the resistant strains. In contrast, the binding of BOCILLIN FL to a low molecular weight protein, PBP6, a D-alanyl-d-alanine carboxypeptidase that was more abundant in all three resistant strains, was substantially increased. A competition assay with β-lactams reduced the binding of all of the PBPs, including PBP6, to BOCILLIN FL. β-Lactams enhanced transcription of the putative gene for PBP6 in both wild type and resistant strains. This is the first report showing that mutations in a high molecular weight PBP and overexpression of a low molecular weight PBP in resistant C. perfringens strains affected their binding to β-lactams.
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Affiliation(s)
- Miseon Park
- Division of Microbiology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR, 71602, USA
| | - John B Sutherland
- Division of Microbiology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR, 71602, USA
| | - Fatemeh Rafii
- Division of Microbiology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, AR, 71602, USA.
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6
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Novel and Improved Crystal Structures of H. influenzae, E. coli and P. aeruginosa Penicillin-Binding Protein 3 (PBP3) and N. gonorrhoeae PBP2: Toward a Better Understanding of β-Lactam Target-Mediated Resistance. J Mol Biol 2019; 431:3501-3519. [PMID: 31301409 DOI: 10.1016/j.jmb.2019.07.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Revised: 07/02/2019] [Accepted: 07/02/2019] [Indexed: 01/26/2023]
Abstract
Even with the emergence of antibiotic resistance, penicillin and the wider family of β-lactams have remained the single most important family of antibiotics. The periplasmic/extra-cytoplasmic targets of penicillin are a family of enzymes with a highly conserved catalytic activity involved in the final stage of bacterial cell wall (peptidoglycan) biosynthesis. Named after their ability to bind penicillin, rather than their catalytic activity, these key targets are called penicillin-binding proteins (PBPs). Resistance is predominantly mediated by reducing the target drug concentration via β-lactamases; however, naturally transformable bacteria have also acquired target-mediated resistance by inter-species recombination. Here we focus on structural based interpretations of amino acid alterations associated with the emergence of resistance within clinical isolates and include new PBP3 structures along with new, and improved, PBP-β-lactam co-structures.
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7
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Fu J, Li L, Liang Z, Xu S, Lin N, Qin P, Ye X, McGrath E. Etiology of acute otitis media and phenotypic-molecular characterization of Streptococcus pneumoniae isolated from children in Liuzhou, China. BMC Infect Dis 2019; 19:168. [PMID: 30770718 PMCID: PMC6377742 DOI: 10.1186/s12879-019-3795-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 02/08/2019] [Indexed: 11/24/2022] Open
Abstract
Background The etiology and epidemiology of acute otitis media (AOM) are poorly understood in China. This study aimed to describe the etiology of AOM and the phenotypic and molecular characteristics of AOM-causing Streptococcus pneumoniae (S.pneumoniae) recovered from Chinese children. Methods A retrospective study was conducted to enrol patients younger than 18 years diagnosed as AOM. Middle ear fluid specimens were collected then cultured for bacterial pathogens. All S.pneumoniae isolates were tested for antibiotic susceptibility, serotypes, virulence genes, antibiotic resistant determinants and sequence types. Results The dominant otopathogen among AOM children was S.pneumoniae (54.4%). Among S.pneumoniae isolates, there were 97.3, 97.3 and 75.7% isolates resistant to erythromycin, tetracycline and trimethoprim-sulfamethoxazole, respectively. There was 72.8% S.pneumoniae with multidrug resistance. The dominant sequence types (STs) were ST271 and ST320, whereas the prevailing serotypes were 19F and 19A. The 7-valent and 13-valent pneumococcal conjugate vaccine (PCV) coverage among AOM children were 73.0 and 94.6%, respectively. Additionally, we found that CC271 expressed more of mef(A/E) (P < 0.001), pspA (P = 0.022) and sipA (P < 0.001) than non-CC271 isolates. Conclusion The high prevalence of international multidrug-resistant clone (Taiwan19F-14) in China necessitates continued dedication to expand PCV13 immunization and better control of antibiotic use in China.
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Affiliation(s)
- Jinjian Fu
- Department of Laboratory, Liuzhou Maternity and Child Healthcare Hospital, Liuzhou, China
| | - Ling Li
- School of Public Health, Guangdong Pharmaceutical University, 283# Jianghai Dadao, Haizhu District, Guangzhou, 510310, China
| | - Zhuoxin Liang
- Department of Pediatric, Liuzhou Maternity and Child Health Care Hospital, Liuzhou, Guangxi, China
| | - Shaolin Xu
- Department of Laboratory, Liuzhou Maternity and Child Healthcare Hospital, Liuzhou, China
| | - Nan Lin
- Department of Otolaryngology, Liuzhou Maternity and Child Health Care Hospital, Liuzhou, Guangxi, China
| | - Peixu Qin
- Department of Laboratory, Liuzhou Maternity and Child Healthcare Hospital, Liuzhou, China
| | - Xiaohua Ye
- School of Public Health, Guangdong Pharmaceutical University, 283# Jianghai Dadao, Haizhu District, Guangzhou, 510310, China.
| | - Eric McGrath
- Children's Hospital of Michigan, Detroit, MI, USA.,Wayne State University School of Medicine, Detroit, MI, USA
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8
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Blanquart F, Lehtinen S, Fraser C. An evolutionary model to predict the frequency of antibiotic resistance under seasonal antibiotic use, and an application to Streptococcus pneumoniae. Proc Biol Sci 2017; 284:rspb.2017.0679. [PMID: 28566489 PMCID: PMC5454275 DOI: 10.1098/rspb.2017.0679] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 05/02/2017] [Indexed: 11/12/2022] Open
Abstract
The frequency of resistance to antibiotics in Streptococcus pneumoniae has been stable over recent decades. For example, penicillin non-susceptibility in Europe has fluctuated between 12% and 16% without any major time trend. In spite of long-term stability, resistance fluctuates over short time scales, presumably in part due to seasonal fluctuations in antibiotic prescriptions. Here, we develop a model that describes the evolution of antibiotic resistance under selection by multiple antibiotics prescribed at seasonally changing rates. This model was inspired by, and fitted to, published data on monthly antibiotics prescriptions and frequency of resistance in two communities in Israel over 5 years. Seasonal fluctuations in antibiotic usage translate into small fluctuations of the frequency of resistance around the average value. We describe these dynamics using a perturbation approach that encapsulates all ecological and evolutionary forces into a generic model, whose parameters quantify a force stabilizing the frequency of resistance around the equilibrium and the sensitivity of the population to antibiotic selection. Fitting the model to the data revealed a strong stabilizing force, typically two to five times stronger than direct selection due to antibiotics. The strong stabilizing force explains that resistance fluctuates in phase with usage, as antibiotic selection alone would result in resistance fluctuating behind usage with a lag of three months when antibiotic use is seasonal. While most antibiotics selected for increased resistance, intriguingly, cephalosporins selected for decreased resistance to penicillins and macrolides, an effect consistent in the two communities. One extra monthly prescription of cephalosporins per 1000 children decreased the frequency of penicillin-resistant strains by 1.7%. This model emerges under minimal assumptions, quantifies the forces acting on resistance and explains up to 43% of the temporal variation in resistance.
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Affiliation(s)
- François Blanquart
- Department of Infectious Disease Epidemiology, Imperial College London, London, UK
| | - Sonja Lehtinen
- Department of Infectious Disease Epidemiology, Imperial College London, London, UK.,Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Christophe Fraser
- Department of Infectious Disease Epidemiology, Imperial College London, London, UK.,Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, Nuffield Department of Medicine, University of Oxford, Oxford, UK
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9
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Diversity of Mosaic pbp2x Families in Penicillin-Resistant Streptococcus pneumoniae from Iran and Romania. Antimicrob Agents Chemother 2017; 61:AAC.01535-17. [PMID: 28971878 PMCID: PMC5700355 DOI: 10.1128/aac.01535-17] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 09/19/2017] [Indexed: 11/20/2022] Open
Abstract
Penicillin-resistant Streptococcus pneumoniae strains are found at high rates in Romania and Iran. The mosaic structure of PBP2x was investigated in 9 strains from Iran and in 15 strains from Romania to understand their evolutionary history. Mutations potentially important for β-lactam resistance were identified by comparison of the PBP2x sequences with the sequence of the related PBP2x of reference penicillin-sensitive S. mitis strains. Two main PBP2x mosaic gene families were recognized. Eight Iranian strains expressed PBP2x variants in group 1, which had a mosaic block highly related to PBP2x of the Spain23F-1 clone, which is widespread among international penicillin-resistant S. pneumoniae clones. A second unique PBP2x group was observed in Romanian strains; furthermore, three PBP2x single mosaic variants were found. Sequence blocks of penicillin-sensitive strain S. mitis 658 were common among PBP2x variants from strains from both countries. Each PBP2x group contained specific signature mutations within the transpeptidase domain, documenting the existence of distinct mutational pathways for the development of penicillin resistance.
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10
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El Moujaber G, Osman M, Rafei R, Dabboussi F, Hamze M. Molecular mechanisms and epidemiology of resistance in Streptococcus pneumoniae in the Middle East region. J Med Microbiol 2017. [DOI: 10.1099/jmm.0.000503] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Grace El Moujaber
- Laboratoire Microbiologie Santé et Environnement (LMSE), Ecole Doctorale des Sciences et de Technologie, Faculté de Santé Publique, Université Libanaise, Tripoli, Lebanon
| | - Marwan Osman
- Laboratoire Microbiologie Santé et Environnement (LMSE), Ecole Doctorale des Sciences et de Technologie, Faculté de Santé Publique, Université Libanaise, Tripoli, Lebanon
| | - Rayane Rafei
- Laboratoire Microbiologie Santé et Environnement (LMSE), Ecole Doctorale des Sciences et de Technologie, Faculté de Santé Publique, Université Libanaise, Tripoli, Lebanon
| | - Fouad Dabboussi
- Laboratoire Microbiologie Santé et Environnement (LMSE), Ecole Doctorale des Sciences et de Technologie, Faculté de Santé Publique, Université Libanaise, Tripoli, Lebanon
| | - Monzer Hamze
- Laboratoire Microbiologie Santé et Environnement (LMSE), Ecole Doctorale des Sciences et de Technologie, Faculté de Santé Publique, Université Libanaise, Tripoli, Lebanon
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11
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Pfaller MA, Mendes RE, Flamm RK, Jones RN, Sader HS. Ceftaroline Activity Against Multidrug-Resistant Streptococcus pneumoniae from U.S. Medical Centers (2014) and Molecular Characterization of a Single Ceftaroline Nonsusceptible Isolate. Microb Drug Resist 2017; 23:571-579. [PMID: 27918694 DOI: 10.1089/mdr.2016.0258] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Streptococcus pneumoniae isolates (2,614) were collected from patients at 135 U.S. Medical Centers during 2014. Isolates were evaluated for multidrug resistance to penicillin, ceftriaxone, erythromycin, tetracycline, trimethoprim-sulfamethoxazole, and levofloxacin. A single isolate (853008) demonstrated a ceftaroline nonsusceptible minimal inhibitory concentration (MIC) value, and it was subjected to molecular characterization. Ceftaroline (MIC50/90, ≤0.015/0.12 μg/ml) was eightfold more potent than ceftriaxone (MIC50/90, ≤0.06/1 μg/ml) against all isolates. For multidrug-resistant (MDR) isolates (28.8% of tested strains), ceftaroline (MIC50/90, 0.06/0.25 μg/ml; 99.9% susceptible) was the most active agent tested, being eightfold more active than ceftriaxone (MIC50/90, 0.25/2 μg/ml; 81.5% susceptible at MIC, ≤1 μg/ml) and 16-fold more active than penicillin (MIC50/90, 0.25/4 μg/ml; 78.5% susceptible at MIC, ≤2 μg/ml). Isolate 853008 was a single locus variant of sequence type 377 and serotype 35B. It had multiple substitutions in the penicillin-binding proteins (PBPs), mainly PBP2x, when compared with reference sequences from the R6 strain. Isolate 853008 showed 31 amino acid alterations in MurM. The in vitro data presented here confirm that ceftaroline potency against S. pneumoniae to be higher than other β-lactams, including against those isolates demonstrating ceftriaxone nonsusceptible and MDR phenotypes.
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Affiliation(s)
- Michael A Pfaller
- 1 JMI Laboratories , North Liberty, Iowa
- 2 University of Iowa , Iowa City, Iowa
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12
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Park M, Rafii F. Exposure to β-lactams results in the alteration of penicillin-binding proteins in Clostridium perfringens. Anaerobe 2017; 45:78-85. [PMID: 28185856 DOI: 10.1016/j.anaerobe.2017.02.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Revised: 02/03/2017] [Accepted: 02/05/2017] [Indexed: 10/20/2022]
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13
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Kim L, McGee L, Tomczyk S, Beall B. Biological and Epidemiological Features of Antibiotic-Resistant Streptococcus pneumoniae in Pre- and Post-Conjugate Vaccine Eras: a United States Perspective. Clin Microbiol Rev 2016; 29:525-52. [PMID: 27076637 PMCID: PMC4861989 DOI: 10.1128/cmr.00058-15] [Citation(s) in RCA: 169] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Streptococcus pneumoniae inflicts a huge disease burden as the leading cause of community-acquired pneumonia and meningitis. Soon after mainstream antibiotic usage, multiresistant pneumococcal clones emerged and disseminated worldwide. Resistant clones are generated through adaptation to antibiotic pressures imposed while naturally residing within the human upper respiratory tract. Here, a huge array of related commensal streptococcal strains transfers core genomic and accessory resistance determinants to the highly transformable pneumococcus. β-Lactam resistance is the hallmark of pneumococcal adaptability, requiring multiple independent recombination events that are traceable to nonpneumococcal origins and stably perpetuated in multiresistant clonal complexes. Pneumococcal strains with elevated MICs of β-lactams are most often resistant to additional antibiotics. Basic underlying mechanisms of most pneumococcal resistances have been identified, although new insights that increase our understanding are continually provided. Although all pneumococcal infections can be successfully treated with antibiotics, the available choices are limited for some strains. Invasive pneumococcal disease data compiled during 1998 to 2013 through the population-based Active Bacterial Core surveillance program (U.S. population base of 30,600,000) demonstrate that targeting prevalent capsular serotypes with conjugate vaccines (7-valent and 13-valent vaccines implemented in 2000 and 2010, respectively) is extremely effective in reducing resistant infections. Nonetheless, resistant non-vaccine-serotype clones continue to emerge and expand.
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Affiliation(s)
- Lindsay Kim
- Epidemiology Section, Respiratory Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Lesley McGee
- Streptococcus Laboratory, Respiratory Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Sara Tomczyk
- Epidemiology Section, Respiratory Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
| | - Bernard Beall
- Streptococcus Laboratory, Respiratory Diseases Branch, Centers for Disease Control and Prevention, Atlanta, Georgia, USA
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Fisher JF, Mobashery S. β-Lactam Resistance Mechanisms: Gram-Positive Bacteria and Mycobacterium tuberculosis. Cold Spring Harb Perspect Med 2016; 6:cshperspect.a025221. [PMID: 27091943 DOI: 10.1101/cshperspect.a025221] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The value of the β-lactam antibiotics for the control of bacterial infection has eroded with time. Three Gram-positive human pathogens that were once routinely susceptible to β-lactam chemotherapy-Streptococcus pneumoniae, Enterococcus faecium, and Staphylococcus aureus-now are not. Although a fourth bacterium, the acid-fast (but not Gram-positive-staining) Mycobacterium tuberculosis, has intrinsic resistance to earlier β-lactams, the emergence of strains of this bacterium resistant to virtually all other antibiotics has compelled the evaluation of newer β-lactam combinations as possible contributors to the multidrug chemotherapy required to control tubercular infection. The emerging molecular-level understanding of these resistance mechanisms used by these four bacteria provides the conceptual framework for bringing forward new β-lactams, and new β-lactam strategies, for the future control of their infections.
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Affiliation(s)
- Jed F Fisher
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556-5670
| | - Shahriar Mobashery
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556-5670
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15
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Variability of β-lactam susceptibility testing for Streptococcus pneumoniae using 4 commercial test methods and broth microdilution. Diagn Microbiol Infect Dis 2016; 84:240-5. [DOI: 10.1016/j.diagmicrobio.2015.11.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Revised: 11/09/2015] [Accepted: 11/15/2015] [Indexed: 11/23/2022]
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16
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Hakenbeck R. Discovery of β-lactam-resistant variants in diverse pneumococcal populations. Genome Med 2014; 6:72. [PMID: 25473434 PMCID: PMC4254413 DOI: 10.1186/s13073-014-0072-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Accepted: 09/10/2014] [Indexed: 01/09/2023] Open
Abstract
Understanding of antibiotic resistance in Streptococcus pneumoniae has been hindered by the low frequency of recombination events in bacteria and thus the presence of large linked haplotype blocks, which preclude identification of causative variants. A recent study combining a large number of genomes of resistant phenotypes has given an insight into the evolving resistance to β-lactams, providing the first large-scale identification of candidate variants underlying resistance.
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Affiliation(s)
- Regine Hakenbeck
- Department of Microbiology, University of Kaiserslautern, Paul-Ehrlich Strasse, Gebäude 23, D-67663, Kaiserslautern, Germany ; Alfried Krupp Wissenschaftskolleg Greifswald, D-17487 Greifswald, Germany
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17
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Nunney L, Hopkins DL, Morano LD, Russell SE, Stouthamer R. Intersubspecific recombination in Xylella fastidiosa Strains native to the United States: infection of novel hosts associated with an unsuccessful invasion. Appl Environ Microbiol 2014; 80:1159-69. [PMID: 24296499 PMCID: PMC3911225 DOI: 10.1128/aem.02920-13] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Accepted: 11/25/2013] [Indexed: 11/20/2022] Open
Abstract
The bacterial pathogen Xylella fastidiosa infects xylem and causes disease in many plant species in the Americas. Different subspecies of this bacterium and different genotypes within subspecies infect different plant hosts, but the genetics of host adaptation are unknown. Here we examined the hypothesis that the introduction of novel genetic variation via intersubspecific homologous recombination (IHR) facilitates host shifts. We investigated IHR in 33 X. fastidiosa subsp. multiplex isolates previously identified as recombinant based on 8 loci (7 multilocus sequence typing [MLST] loci plus 1 locus). We found significant evidence of introgression from X. fastidiosa subsp. fastidiosa in 4 of the loci and, using published data, evidence of IHR in 6 of 9 additional loci. Our data showed that IHR regions in 2 of the 4 loci were inconsistent (12 mismatches) with X. fastidiosa subsp. fastidiosa alleles found in the United States but consistent with alleles from Central America. The other two loci were consistent with alleles from both regions. We propose that the recombinant forms all originated via genomewide recombination of one X. fastidiosa subsp. multiplex ancestor with one X. fastidiosa subsp. fastidiosa donor from Central America that was introduced into the United States but subsequently disappeared. Using all of the available data, 5 plant hosts of the recombinant types were identified, 3 of which also supported non-IHR X. fastidiosa subsp. multiplex, but 2 were unique to recombinant types from blueberry (7 isolates from Georgia, 3 from Florida); and blackberry (1 each from Florida and North Carolina), strongly supporting the hypothesis that IHR facilitated a host shift to blueberry and possibly blackberry.
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Affiliation(s)
- Leonard Nunney
- Biology Department, University of California, Riverside, California, USA
| | - Donald L. Hopkins
- University of Florida, Mid-Florida Research and Education Center, Apopka, Florida, USA
| | - Lisa D. Morano
- Department of Natural Sciences, University of Houston—Downtown, Houston, Texas, USA
| | | | - Richard Stouthamer
- Entomology Department, University of California, Riverside, California, USA
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18
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Abstract
The beta-lactam family of antimicrobials, in particular penicillins and cephalosporins, is the mainstay of treatment for community-acquired infections. However, the emergence of resistant isolates to these agents has raised concerns regarding the continued efficacy of existing therapies. Resistance to beta-lactams is most commonly expressed by the microbial production of beta-lactamases that hydrolyze the beta-lactam ring. Three further resistance mechanisms include conformational changes in penicillin-binding proteins (PBPs); permeability changes in the outer membrane; and active efflux of the antimicrobial. In addition to the pre-requisite efficacy and tolerability profiles, new beta-lactams should address these four resistance mechanisms. Overcoming resistance may be a serendipitous event or arrived at by design. A unique synthetic beta-lactam class, which demonstrates promise in terms of its activity against the range of bacteria responsible for community-acquired infections and its inherent stability to hydrolysis by beta-lactamases, is the penems. This discrete class of hybrid molecules combines properties from the penicillin (penam) and cephalosporin (cephem) beta-lactam classes. Faropenem is an example of a penem with a broad spectrum of activity designed to address these resistance issues.
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Affiliation(s)
- S G B Amyes
- Medical Microbiology, University of Edinburgh Medical School, Teviot Place, Edinburgh, EH8 9AG, UK
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19
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Fani F, Brotherton MC, Leprohon P, Ouellette M. Genomic analysis and reconstruction of cefotaxime resistance in Streptococcus pneumoniae. J Antimicrob Chemother 2013; 68:1718-27. [PMID: 23608923 DOI: 10.1093/jac/dkt113] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVES To identify non-penicillin-binding protein (PBP) mutations contributing to resistance to the third-generation cephalosporin cefotaxime in Streptococcus pneumoniae at the genome-wide scale. METHODS The genomes of two in vitro S. pneumoniae cefotaxime-resistant isolates and of two transformants serially transformed with the genomic DNA of cefotaxime-resistant mutants were determined by next-generation sequencing. A role in cefotaxime resistance for the mutations identified was confirmed by reconstructing resistance in a cefotaxime-susceptible background. RESULTS Analysis of the genome assemblies revealed mutations in genes coding for the PBPs 2x, 2a and 3, of which pbp2x was the only mutated gene common to all mutants. The transformation of altered PBP alleles into S. pneumoniae R6 confirmed the role of PBP mutations in cefotaxime resistance, but these were not sufficient to fully explain the levels of resistance. Thirty-one additional genes were found to be mutated in at least one of the four sequenced genomes. Non-PBP resistance determinants appeared to be mostly lineage specific. Mutations in spr1333, spr0981, spr1704 and spr1098, encoding a peptidoglycan N-acetylglucosamine deacetylase, a glycosyltransferase, an ABC transporter and a sortase, respectively, were implicated in resistance by transformation experiments and allowed the reconstruction of the full level of resistance observed in the parent resistant strains. CONCLUSIONS This whole-genome analysis coupled to functional studies has allowed the discovery of both known and novel cefotaxime resistance genes in S. pneumoniae.
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Affiliation(s)
- Fereshteh Fani
- Centre de recherche en Infectiologie du Centre de recherche du CHUL and Département de Microbiologie, Infectiologie et Immunologie, Faculté de Médecine, Université Laval, Québec, Canada
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20
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Hakenbeck R, Brückner R, Denapaite D, Maurer P. Molecular mechanisms of β-lactam resistance in Streptococcus pneumoniae. Future Microbiol 2012; 7:395-410. [PMID: 22393892 DOI: 10.2217/fmb.12.2] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Alterations in the target enzymes for β-lactam antibiotics, the penicillin-binding proteins (PBPs), have been recognized as a major resistance mechanism in Streptococcus pneumoniae. Mutations in PBPs that confer a reduced affinity to β-lactams have been identified in laboratory mutants and clinical isolates, and document an astounding variability of sites involved in this phenotype. Whereas point mutations are selected in the laboratory, clinical isolates display a mosaic structure of the affected PBP genes, the result of interspecies gene transfer and recombination events. Depending on the selective β-lactam, different combinations of PBP genes and mutations within are involved in conferring resistance, and astoundingly in non-PBP genes as well.
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Affiliation(s)
- Regine Hakenbeck
- Department of Microbiology, University of Kaiserslautern, Paul Ehrlich Strasse 23, D-67663 Kaiserslautern, Germany.
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21
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Harrison OB, Brueggemann AB, Caugant DA, van der Ende A, Frosch M, Gray S, Heuberger S, Krizova P, Olcen P, Slack M, Taha MK, Maiden MCJ. Molecular typing methods for outbreak detection and surveillance of invasive disease caused by Neisseria meningitidis, Haemophilus influenzae and Streptococcus pneumoniae, a review. MICROBIOLOGY (READING, ENGLAND) 2011; 157:2181-2195. [PMID: 21622526 PMCID: PMC3980633 DOI: 10.1099/mic.0.050518-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Invasive disease caused by the encapsulated bacteria Neisseria meningitidis, Haemophilus influenzae and Streptococcus pneumoniae remains an important cause of morbidity and mortality worldwide, despite the introduction of successful conjugate polysaccharide vaccines that target disease-associated strains. In addition, resistance, or more accurately reduced susceptibility, to therapeutic antibiotics is spreading in populations of these organisms. There is therefore a continuing requirement for the surveillance of vaccine and non-vaccine antigens and antibiotic susceptibilities among isolates from invasive disease, which is only partially met by conventional methods. This need can be met with molecular and especially nucleotide sequence-based typing methods, which are fully developed in the case of N. meningitidis and which could be more widely deployed in clinical laboratories for S. pneumoniae and H. influenzae.
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Affiliation(s)
- Odile B. Harrison
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK
| | | | - Dominique A. Caugant
- Department of Bacteriology and Immunology, Norwegian Institute of Public Health, PO Box 4404 Nydalen, NO-0403 Oslo, Norway
| | - Arie van der Ende
- Academic Medical Center, Department of Medical Microbiology, Reference Laboratory for Bacterial Meningitis, PO Box 22660, 1100 DD Amsterdam, The Netherlands
| | - Matthias Frosch
- Institut für Hygiene und Mikrobiologie, Universität Würzburg, Josef-Schneider Strasse 2, 97080 Würzburg, Germany
| | - Stephen Gray
- Meningococcal Reference Unit, Health Protection Agency, PO Box 209, Clinical Sciences Building 2, Manchester Royal Infirmary, Oxford Road, Manchester M13 9WZ, UK
| | - Sigrid Heuberger
- Österreichische Agentur für Gesundheit und Ernährungssicherheit GmbH, Bereich Humanmedizin, Institut für medizinische Mikrobiologie und Hygiene, Beethovenstraße 6, A-8010 Graz, Austria
| | - Paula Krizova
- National Reference Laboratory for Meningococcal Infections, National Institute of Public Health, Srobarova 48, Prague, Czech Republic
| | - Per Olcen
- Department of Laboratory Medicine, Clinical Microbiology and Immunology, Orebro University Hospital, SE-701 85 Orebro, Sweden
| | - Mary Slack
- Respiratory and Systemic Infection Laboratory, Health Protection Agency Centre for Infections, 61 Colindale Avenue, London NW9 5EQ, UK
| | | | - Martin C. J Maiden
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK
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22
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Sheppard SK, McCarthy ND, Jolley KA, Maiden MCJ. Introgression in the genus Campylobacter: generation and spread of mosaic alleles. MICROBIOLOGY-SGM 2011; 157:1066-1074. [PMID: 21212120 PMCID: PMC3139442 DOI: 10.1099/mic.0.045153-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Horizontal genetic exchange strongly influences the evolution of many bacteria, substantially contributing to difficulties in defining their position in taxonomic groups. In particular, how clusters of related bacterial genotypes – currently classified as microbiological species – evolve and are maintained remains controversial. The nature and magnitude of gene exchange between two closely related (approx. 15 % nucleotide divergence) microbiologically defined species, Campylobacter jejuni and Campylobacter coli, was investigated by the examination of mosaic alleles, those with some ancestry from each population. A total of 1738 alleles from 2953 seven-locus housekeeping gene sequence types (STs) were probabilistically assigned to each species group with the model-based clustering algorithm structure. Alleles with less than 75 % assignment probability to one of the populations were confirmed as mosaics using the structure linkage model. For each of these, the putative source of the recombinant region was determined and the allele was mapped onto a clonalframe genealogy derived from concatenated ST sequences. This enabled the direction and frequency of introgression between the two populations to be established, with 8.3 % of C. coli clade 1 alleles having acquired C. jejuni sequence, compared to 0.5 % for the reciprocal process. Once generated, mosaic genes spread within C. coli clade 1 by a combination of clonal expansion and lateral gene transfer, with some evidence of erosion of the mosaics by reacquisition of C. coli sequence. These observations confirm previous analyses of the exchange of complete housekeeping alleles and extend this work by describing the processes of horizontal gene transfer and subsequent spread within recipient species.
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Affiliation(s)
- Samuel K Sheppard
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK
| | - Noel D McCarthy
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK
| | - Keith A Jolley
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK
| | - Martin C J Maiden
- Department of Zoology, University of Oxford, South Parks Road, Oxford OX1 3PS, UK
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23
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Tsurusako, Kunihiro Fukushima, Kazu Y. The Alteration of Penicillin-Binding Proteins (PBPs) in Drug-resistant Streptococcus pneumoniae Isolated from Acute Otitis Media. Acta Otolaryngol 2009. [DOI: 10.1080/00016489950181233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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24
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Comparative antipneumococcal activities of sulopenem and other drugs. Antimicrob Agents Chemother 2009; 53:2239-47. [PMID: 19307366 DOI: 10.1128/aac.01531-08] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
For 297 penicillin-susceptible, -intermediate, and -resistant pneumococcal strains, the sulopenem MIC(50)s were 0.008, 0.06, and 0.25, respectively, and the sulopenem MIC(90)s were 0.016, 0.25, and 0.5 microg/ml, respectively. The MIC(50)s of amoxicillin for the corresponding strains were 0.03, 0.25, and 2.0 microg/ml, respectively, and the MIC(90)s were 0.03, 1.0, and 8.0 microg/ml, respectively. The combination of amoxicillin and clavulanate gave MICs similar to those obtained with amoxicillin alone. The sulopenem MICs were similar to those of imipenem and meropenem. The MICs of ss-lactams increased with those of penicillin G, and among the quinolones tested, moxifloxacin had the lowest MICs. Additionally, 45 strains of drug-resistant type 19A pneumococci were tested by agar dilution and gave sulopenem MIC(50)s and MIC(90)s of 1.0 and 2.0 microg/ml, respectively. Both sulopenem and amoxicillin (with and without clavulanate) were bactericidal against all 12 strains tested at 2x MIC after 24 h. Thirty-one strains from 10 countries with various penicillin, amoxicillin, and carbapenems MICs, including those with the highest sulopenem MICs, were selected for sequencing analysis of the pbp1a, pbp2x, and pbp2b regions encoding the transpeptidase active site and MurM. We did not find any correlations between specific penicillin-binding protein-MurM patterns and changes in the MICs.
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25
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McGee L, Biek D, Ge Y, Klugman M, du Plessis M, Smith AM, Beall B, Whitney CG, Klugman KP. In vitro evaluation of the antimicrobial activity of ceftaroline against cephalosporin-resistant isolates of Streptococcus pneumoniae. Antimicrob Agents Chemother 2009; 53:552-6. [PMID: 19015339 PMCID: PMC2630653 DOI: 10.1128/aac.01324-08] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2008] [Revised: 10/31/2008] [Accepted: 11/09/2008] [Indexed: 11/20/2022] Open
Abstract
Increasing pneumococcal resistance to extended-spectrum cephalosporins warrants the search for novel agents with activity against such resistant strains. Ceftaroline, a parenteral cephalosporin currently in phase 3 clinical development, has demonstrated potent in vitro activity against resistant gram-positive organisms, including penicillin-resistant Streptococcus pneumoniae. In this study, the activity of ceftaroline was evaluated against highly cefotaxime-resistant isolates of pneumococci from the Active Bacterial Core surveillance program of the Centers for Disease Control and Prevention and against laboratory-derived cephalosporin-resistant mutants of S. pneumoniae. The MICs of ceftaroline and comparators were determined by broth microdilution. In total, 120 U.S. isolates of cefotaxime-resistant (MIC > or = 4 microg/ml) S. pneumoniae were tested along with 18 laboratory-derived R6 strains with known penicillin-binding protein (PBP) mutations. Clinical isolates were characterized by multilocus sequence typing, and the DNAs of selected isolates were sequenced to identify mutations affecting pbp genes. Ceftaroline (MIC(90) = 0.5 microg/ml) had greater in vitro activity than penicillin, cefotaxime, or ceftriaxone (MIC(90) = 8 microg/ml for all comparators) against the set of highly cephalosporin-resistant clinical isolates of S. pneumoniae. Ceftaroline was also more active against the defined R6 PBP mutant strains, which suggests that ceftaroline can overcome common mechanisms of PBP-mediated cephalosporin resistance. These data indicate that ceftaroline has significant potency against S. pneumoniae strains resistant to existing parenteral cephalosporins and support its continued development for the treatment of infections caused by resistant S. pneumoniae strains.
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26
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An important site in PBP2x of penicillin-resistant clinical isolates of Streptococcus pneumoniae: mutational analysis of Thr338. Antimicrob Agents Chemother 2008; 53:1107-15. [PMID: 19075056 DOI: 10.1128/aac.01107-08] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Penicillin-binding protein 2x (PBP2x) of Streptococcus pneumoniae represents a primary resistance determinant for beta-lactams, and low-affinity PBP2x variants can easily be selected with cefotaxime. Penicillin-resistant clinical isolates of S. pneumoniae frequently contain in their mosaic PBP2x the mutation T338A adjacent to the active site S337, and T338P as well as T338G substitutions are also known. Site-directed mutagenesis has now documented that a single point mutation at position T338 confers selectable levels of beta-lactam resistance preferentially to oxacillin. Despite the moderate impact on beta-lactam susceptibility, the function of the PBP2x mutants appears to be impaired, as can be documented in the absence of a functional CiaRH regulatory system, resulting in growth defects and morphological changes. The combination of low-affinity PBP2x and PBP1a encoded by mosaic genes is known to result in high cefotaxime resistance. In contrast, introduction of a mosaic pbp1a into the PBP2x(T338G) mutant did not lead to increased resistance. However, the mosaic PBP1a gene apparently complemented the PBP2x(T338G) defect, since Cia mutant derivatives grew normally. The data support the view that PBP2x and PBP1a interact with each other on some level and that alterations of both PBPs in resistant clinical isolates have evolved to ensure cooperation between both proteins.
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27
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Serotype distribution and antimicrobial resistance patterns of Streptococcus pneumoniae isolated from children in China younger than 5 years. Diagn Microbiol Infect Dis 2008; 61:256-63. [PMID: 18358662 DOI: 10.1016/j.diagmicrobio.2008.02.004] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2007] [Revised: 02/06/2008] [Accepted: 02/07/2008] [Indexed: 11/22/2022]
Abstract
This study examined the epidemiology, antibiotic susceptibility, and serotype distribution of Streptococcus pneumoniae associated with invasive and noninvasive pneumococcal disease in children in China. A total of 451 clinical isolates from children (age, <5 years) were collected from 8 cities from January 2005 to December 2006, including 31 isolated from invasive disease. In vitro susceptibility to 14 antimicrobial agents was determined by the agar dilution method. Among all isolates tested, 64.3% were resistant to penicillin, and for invasive isolates, the resistance rate was 55.2%. Isolates from Wuhan and Nanjing showed the highest prevalence of penicillin resistance (89.6% and 85%), followed by those from Shenzhen (72.4%) and Chengdu (56.7%). Multidrug resistance rates to tetracycline, erythromycin, and clindamycin reached 90%. The 6 most common serotypes were 19F, 19A, 14, 6B, 23F, and 15. These accounted for 80.7% of the isolates. Resistance to penicillin varied among the 6 leading serotypes, ranging from 20% in serotype 15 to 87.3% in serotype 19F. Each of the 8 cities had different serotype distribution. The potential coverage by 7-, 10-, and 13-valent pneumococcal conjugate vaccine were 63.6%, 64.8%, and 79.6%, respectively.
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28
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Stanhope MJ, Lefébure T, Walsh SL, Becker JA, Lang P, Pavinski Bitar PD, Miller LA, Italia MJ, Amrine-Madsen H. Positive selection in penicillin-binding proteins 1a, 2b, and 2x from Streptococcus pneumoniae and its correlation with amoxicillin resistance development. INFECTION GENETICS AND EVOLUTION 2008; 8:331-9. [PMID: 18394970 DOI: 10.1016/j.meegid.2008.02.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2007] [Revised: 02/06/2008] [Accepted: 02/08/2008] [Indexed: 11/29/2022]
Abstract
The efficacy of beta-lactam antibiotics in Streptococcus pneumoniae has been compromised because of the development of altered penicillin-binding proteins (PBPs), however, this has been less so for amoxicillin than for penicillin. Recently, there have been a number of important methods developed to detect molecular adaptation in protein coding genes. The purpose of this study is to employ modern molecular selection approaches to predict sites under positive selection pressure in PBPs, derived from a large international S. pneumoniae collection of amoxicillin resistant and susceptible isolates, and encompassing a comparative data set of 354 pbp1a, 335 pbp2b, and 389 pbp2x gene sequences. A correspondence discriminant analysis (CDA) of positively selected pbp sites and amoxicillin MIC (minimum inhibitory concentration) values is then used to detect sites under positive selection pressure that are important in discriminating different amoxicillin MICs. Molecular adaptation was evident throughout PBP2X, with numerous positively selected sites in both the transpeptidase (TP) and C-terminal domains, strongly correlated with discriminating amoxicillin MICs. In the case of PBP1A positive selection was present in the glycosyltransfer (GT), TP and C-terminal domains. Sites within the TP domain tended to be correlated with the discrimination of low from intermediate MICs, whereas sites within the C-terminal tail, with a discrimination of intermediate from fully resistant. Most of the positively selected sites within PBP2B were in the N-terminal domain and were not correlated with amoxicillin MICs, however, several sites taken from the literature for the TP domain were strongly associated with discriminating high from intermediate level amoxicillin resistance. Many of the positively selected sites could be directly associated with functional inferences based on the crystal structures of these proteins. Our results suggest that clinical emphasis on TP domain sequences of these proteins may result in missing information relevant to antibiotic resistance development.
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Affiliation(s)
- Michael J Stanhope
- Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
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29
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Brueggemann AB, Pai R, Crook DW, Beall B. Vaccine escape recombinants emerge after pneumococcal vaccination in the United States. PLoS Pathog 2008; 3:e168. [PMID: 18020702 PMCID: PMC2077903 DOI: 10.1371/journal.ppat.0030168] [Citation(s) in RCA: 282] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2007] [Accepted: 09/24/2007] [Indexed: 11/19/2022] Open
Abstract
The heptavalent pneumococcal conjugate vaccine (PCV7) was introduced in the United States (US) in 2000 and has significantly reduced invasive pneumococcal disease; however, the incidence of nonvaccine serotype invasive disease, particularly due to serotype 19A, has increased. The serotype 19A increase can be explained in part by expansion of a genotype that has been circulating in the US prior to vaccine implementation (and other countries since at least 1990), but also by the emergence of a novel “vaccine escape recombinant” pneumococcal strain. This strain has a genotype that previously was only associated with vaccine serotype 4, but now expresses a nonvaccine serotype 19A capsule. Based on prior evidence for capsular switching by recombination at the capsular locus, the genetic event that resulted in this novel serotype/genotype combination might be identifiable from the DNA sequence of individual pneumococcal strains. Therefore, the aim of this study was to characterise the putative recombinational event(s) at the capsular locus that resulted in the change from a vaccine to a nonvaccine capsular type. Sequencing the capsular locus flanking regions of 51 vaccine escape (progeny), recipient, and putative donor pneumococci revealed a 39 kb recombinational fragment, which included the capsular locus, flanking regions, and two adjacent penicillin-binding proteins, and thus resulted in a capsular switch and penicillin nonsusceptibility in a single genetic event. Since 2003, 37 such vaccine escape strains have been detected, some of which had evolved further. Furthermore, two new types of serotype 19A vaccine escape strains emerged in 2005. To our knowledge, this is the first time a single recombinational event has been documented in vivo that resulted in both a change of serotype and penicillin nonsusceptibility. Vaccine escape by genetic recombination at the capsular locus has the potential to reduce PCV7 effectiveness in the longer term. The 7-valent pneumococcal conjugate vaccine is a remarkable public health success story. It has significantly reduced invasive pneumococcal disease in the United States not only by protecting vaccinated children, but also by protecting unvaccinated older children and adults by herd immunity. However, there was always a concern that use of a limited-valency vaccine would result in an increase in disease due to nonvaccine serotypes, and this has now occurred in the US. The predominant nonvaccine serotype causing invasive disease is 19A, and this increase is partially explained by “vaccine escape” pneumococci, strains that have exchanged the genes that encode a vaccine serotype 4 capsule for genes that encode a nonvaccine serotype 19A capsule. These strains are then able to escape vaccine-induced immunity. Characterisation of the genetic event that resulted in these vaccine escape strains was the focus of our study and the results were surprising. The results of this study have important relevance to the long-term effectiveness of the current vaccine and to the development of future pneumococcal vaccines.
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Zapun A, Contreras-Martel C, Vernet T. Penicillin-binding proteins and beta-lactam resistance. FEMS Microbiol Rev 2008; 32:361-85. [PMID: 18248419 DOI: 10.1111/j.1574-6976.2007.00095.x] [Citation(s) in RCA: 386] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
A number of ways and means have evolved to provide resistance to eubacteria challenged by beta-lactams. This review is focused on pathogens that resist by expressing low-affinity targets for these antibiotics, the penicillin-binding proteins (PBPs). Even within this narrow focus, a great variety of strategies have been uncovered such as the acquisition of an additional low-affinity PBP, the overexpression of an endogenous low-affinity PBP, the alteration of endogenous PBPs by point mutations or homologous recombination or a combination of the above.
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Affiliation(s)
- André Zapun
- Laboratoire d'Ingénierie des Macromolécules, Institut de Biologie Structurale Jean-Pierre Ebel, UMR 5075-CNRS, CEA, Université Joseph Fourier, Grenoble, France
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Maurer P, Koch B, Zerfass I, Krauss J, van der Linden M, Frère JM, Contreras-Martel C, Hakenbeck R. Penicillin-binding protein 2x of Streptococcus pneumoniae: three new mutational pathways for remodelling an essential enzyme into a resistance determinant. J Mol Biol 2008; 376:1403-16. [PMID: 18234221 DOI: 10.1016/j.jmb.2007.12.058] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2007] [Revised: 12/14/2007] [Accepted: 12/21/2007] [Indexed: 10/22/2022]
Abstract
Mutations in the transpeptidase domain of penicillin-binding protein 2x (PBP2x) of Streptococcus pneumoniae that reduce the affinity to beta-lactams are important determinants of resistance to these antibiotics. We have now analyzed in vitro and in vivo properties of PBP2x variants from cefotaxime-resistant laboratory mutants and a clinical isolate. The patterns of two to four resistance-specific mutations present in each of the proteins, all of which are placed between 6.6 and 24 A around the active site, fall into three categories according to their positions in the three-dimensional structure. The first PBP2x group is characterized by mutations at the end of helix alpha 11 and carries the well-known T550A change and/or one mutation on the surface of the penicillin-binding domain in close contact with the C-terminal domain. All group I proteins display very low acylation efficiencies, <or=1700 M(-1) s(-1), for cefotaxime. The second class represented by PBP2x of the mutant C505 shows acylation efficiencies below 100 M(-1) s(-1) for both cefotaxime and benzylpenicillin and contains the mutation L403F at a critical site close to the active serine. PBP2x of the clinical isolate 669 reveals a third mutational pathway where at least the two mutations Q552E and S389L are important for resistance, and acylation efficiency is reduced for both beta-lactams to around 10,000 M(-1) s(-1). In each group, at least one mutation is located in close vicinity to the active site and mediates a resistance phenotype in vivo alone, whereas other mutations might exhibit secondary effects only in context with other alterations.
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Affiliation(s)
- Patrick Maurer
- Department of Microbiology, University of Kaiserslautern, Paul-Ehrlich Strasse 23, D-67663 Kaiserslautern, Germany
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Chi F, Nolte O, Bergmann C, Ip M, Hakenbeck R. Crossing the barrier: Evolution and spread of a major class of mosaic pbp2x in Streptococcus pneumoniae, S. mitis and S. oralis. Int J Med Microbiol 2007; 297:503-12. [PMID: 17459765 DOI: 10.1016/j.ijmm.2007.02.009] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2007] [Revised: 02/21/2007] [Accepted: 02/21/2007] [Indexed: 11/28/2022] Open
Abstract
A paradigm for Streptococcus interspecies gene transfer is represented by the mosaic pbp genes encoding the target enzymes for beta-lactam antibiotics, the penicillin-binding proteins, in Streptococcus pneumoniae. We investigated a collection of oral streptococci from three continents by comprehensive multi-locus sequence typing analysis in order to trace the origin of a mosaic block belonging to a dominant family of mosaic pbp2x implicated in penicillin resistance of S. pneumoniae. One widespread family of mosaic pbp2x occurred in all three distinct clusters of S. pneumoniae, Streptococcus mitis and Streptococcus oralis, documenting independent inter- and intraspecies recombination events. Moreover, potential ancestor genes of this mosaic block could be identified in two penicillin-susceptible S. mitis strains from South Africa and Spain, facilitating the identification of pbp2x mutations relevant for resistance development.
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Affiliation(s)
- Fang Chi
- Department of Microbiology, University of Kaiserslautern, Paul Ehrlich Str. 23, D-67663 Kaiserslautern, Germany
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Stanhope MJ, Walsh SL, Becker JA, Miller LA, Lefébure T, Lang P, Bitar PDP, Amrine-Madsen H. The relative frequency of intraspecific lateral gene transfer of penicillin binding proteins 1a, 2b, and 2x, in amoxicillin resistant Streptococcus pneumoniae. INFECTION GENETICS AND EVOLUTION 2007; 7:520-34. [PMID: 17475572 DOI: 10.1016/j.meegid.2007.03.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2006] [Revised: 03/21/2007] [Accepted: 03/23/2007] [Indexed: 11/18/2022]
Abstract
Evidence exists for both interspecific and intraspecific recombination (lateral gene transfer; LGT) involving Streptococcus pneumoniae pbp (penicillin binding protein) loci. LGT of capsular genes, or serotype switching, is also know to occur between S. pneumoniae of different serotype. It is not clear whether intraspecific pbp LGT is relatively common, whether there is a difference in the relative frequency of intraspecific LGT of different pbps, and whether serotype switching is more or less frequent than pbp LGT. The purpose of this study was to use comparative evolutionary biology analysis of 216 international clinical S. pneumoniae isolates, from the Alexander Project collection, to gain insight on these issues, as well as the possible role they might be playing in spreading amoxicillin resistance. All 216 isolates were genotyped using MLST and complete or nearly complete sequences for pbp1a, pbp2b, and pbp2x were determined. Amoxicillin MICs were available for each isolate. pbps were genotyped using phylogenetics and two or more pbp types within a MLST sequence type (ST) or clonal complex were taken as putative cases of pbp LGT; these hypotheses were statistically evaluated using the approximately unbiased (AU) test. Serotypes were determined for 171 of these isolates and the minimum number of switching events necessary to explain the serotype phenotypes for each of the STs and clonal complexes were evaluated. The majority (78%) of the amoxicillin resistant isolates were comprised in 5 clonal complexes. The relative frequency of pbp LGT was greatest for pbp2b and 2x (minimum of 10.2 and 7.8%, respectively, of the isolates consistent with the LGT hypothesis), followed by 1a (3.9%). Serotype switching was more frequent than intraspecific pbp LGT (33% of isolates consistent with serotype switching hypothesis). Although intraspecific LGT of pbps is occurring and has played a role in the spread of amoxicillin resistance in S. pneumoniae, clonal dissemination appears to be more significant.
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Affiliation(s)
- Michael J Stanhope
- Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, United States.
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Chiu CH, Su LH, Huang YC, Lai JC, Chen HL, Wu TL, Lin TY. Increasing ceftriaxone resistance and multiple alterations of penicillin-binding proteins among penicillin-resistant Streptococcus pneumoniae isolates in Taiwan. Antimicrob Agents Chemother 2007; 51:3404-6. [PMID: 17591850 PMCID: PMC2043203 DOI: 10.1128/aac.01563-06] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The rate of nonsusceptibility of penicillin-resistant Streptococcus pneumoniae strains to ceftriaxone increased significantly in Taiwan in 2005. Approximately 90% of the ceftriaxone-nonsusceptible isolates were found to be of four major serotypes (serotypes 6B, 14, 19F, and 23F). Seven amino acid alterations in the penicillin-binding protein 2B transpeptidase-encoding region specifically contributed to the resistance.
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Affiliation(s)
- Cheng-Hsun Chiu
- Department of Pediatrics, Chang Gung Children's Hospital, 5 Fu-Hsin Street, Kweishan 333, Taoyuan, Taiwan.
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Davies TA, Shang W, Bush K. Activities of ceftobiprole and other beta-lactams against Streptococcus pneumoniae clinical isolates from the United States with defined substitutions in penicillin-binding proteins PBP 1a, PBP 2b, and PBP 2x. Antimicrob Agents Chemother 2006; 50:2530-2. [PMID: 16801437 PMCID: PMC1489808 DOI: 10.1128/aac.00238-06] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The activities of ceftobiprole and other beta-lactams were examined with 30 Streptococcus pneumoniae isolates containing multiple pbp1a, pbp2b, and pbp2x mutations. The highest ceftobiprole MIC was 1 microg/ml, while the comparator MICs were 16 to 64 microg/ml. Fifty percent inhibitory concentrations for penicillin-binding protein 2x were 0.5 microg/ml (ceftobiprole) and 4 microg/ml (ceftriaxone) in a penicillin- and ceftriaxone-resistant isolate.
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Affiliation(s)
- Todd A Davies
- Johnson & Johnson Pharmaceutical Research & Development, LLC, Raritan, NJ 08869, USA.
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Mascher T, Heintz M, Zähner D, Merai M, Hakenbeck R. The CiaRH system of Streptococcus pneumoniae prevents lysis during stress induced by treatment with cell wall inhibitors and by mutations in pbp2x involved in beta-lactam resistance. J Bacteriol 2006; 188:1959-68. [PMID: 16484208 PMCID: PMC1426552 DOI: 10.1128/jb.188.5.1959-1968.2006] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The two-component signal-transducing system CiaRH of Streptococcus pneumoniae plays an important role during the development of beta-lactam resistance in laboratory mutants. We show here that a functional CiaRH system is required for survival under many different lysis-inducing conditions. Mutants with an activated CiaRH system were highly resistant to lysis induced by a wide variety of early and late cell wall inhibitors, such as cycloserine, bacitracin, and vancomycin, and were also less susceptible to these drugs. In contrast, loss-of-function CiaRH mutants were hypersusceptible to these drugs and were apparently unable to maintain a stationary growth phase in normal growth medium and under choline deprivation as well. Moreover, disruption of CiaR in penicillin-resistant mutants with an altered pbp2x gene encoding low-affinity PBP2x resulted in severe growth defects and rapid lysis. This phenotype was observed with pbp2x genes containing point mutations selected in the laboratory and with highly altered mosaic pbp2x genes from penicillin-resistant clinical isolates as well. This documents for the first time that PBP2x mutations required for development of beta-lactam resistance are functionally not neutral and are tolerated only in the presence of the CiaRH system. This might explain why cia mutations have not been observed in penicillin-resistant clinical isolates. The results document that the CiaRH system is required for maintenance of the stationary growth phase and for prevention of autolysis triggered under many different conditions, suggesting a major role for this system in ensuring cell wall integrity.
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Affiliation(s)
- Thorsten Mascher
- Department of Microbiology, University of Kaiserslautern, Paul Ehrlich Strasse 23, D-67663 Kaiserslautern, Germany.
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Smith AM, Klugman KP. Amino acid mutations essential to production of an altered PBP 2X conferring high-level beta-lactam resistance in a clinical isolate of Streptococcus pneumoniae. Antimicrob Agents Chemother 2006; 49:4622-7. [PMID: 16251304 PMCID: PMC1280142 DOI: 10.1128/aac.49.11.4622-4627.2005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Altered penicillin-binding protein 2X (PBP 2X) is a primary beta-lactam antibiotic resistance determinant and is essential to the development of penicillin and cephalosporin resistance in the pneumococcus. We have studied the importance for resistance of 23 amino acid substitutions located in the transpeptidase domain (TD) of PBP 2X from an isolate with high-level resistance, isolate 3191 (penicillin MIC, 16 mug/ml; cefotaxime MIC, 4 microg/ml). Strain R6(2X/2B/1A/mur) (for which the MICs are as described for isolate 3191) was constructed by transforming laboratory strain R6 with all the necessary resistance determinants (altered PBPs 2X, 2B, and 1A and altered MurM) from isolate 3191. Site-directed mutagenesis was used to reverse amino acid substitutions in altered PBP 2X, followed by investigation of the impact of these reversions on resistance levels in R6(2X/2B/1A/mur). Of the 23 substitutions located in the TD of PBP 2X, reversals at six positions decreased the resistance levels in R6(2X/2B/1A/mur). Reversal of the Thr338Pro and Ile371Thr substitutions individually decreased the penicillin and cefotaxime MICs to 2 and 1 microg/ml, respectively, and individually displayed the greatest impact on resistance. To a lesser extent, reversal of the Leu364Phe, Ala369Val, Arg384Gly, and Tyr595Phe substitutions individually also decreased the penicillin and cefotaxime MICs. Reversal at all six positions collectively decreased both the penicillin and the cefotaxime MICs of R6(2X/2B/1A/mur) to 0.06 microg/ml. This study confirms the essential role of altered PBP 2X as a resistance determinant. Our data reveal that, for isolate 3191, the six amino acid substitutions described above are collectively essential to the production of an altered PBP 2X required for high-level resistance to penicillin and cefotaxime.
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Affiliation(s)
- Anthony M Smith
- Respiratory and Meningeal Pathogens Research Unit, National Institute for Communicable Diseases, Medical Research Council, Johannesburg, South Africa.
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Contreras-Martel C, Job V, Di Guilmi AM, Vernet T, Dideberg O, Dessen A. Crystal structure of penicillin-binding protein 1a (PBP1a) reveals a mutational hotspot implicated in beta-lactam resistance in Streptococcus pneumoniae. J Mol Biol 2005; 355:684-96. [PMID: 16316661 DOI: 10.1016/j.jmb.2005.10.030] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2005] [Revised: 10/10/2005] [Accepted: 10/11/2005] [Indexed: 11/17/2022]
Abstract
Streptococcus pneumoniae is a major human pathogen whose infections have been treated with beta-lactam antibiotics for over 60 years, but the proliferation of strains that are highly resistant to such drugs is a problem of worldwide concern. Beta-lactams target penicillin-binding proteins (PBPs), membrane-associated enzymes that play essential roles in the peptidoglycan biosynthetic process. Bifunctional PBPs catalyze both the polymerization of glycan chains (glycosyltransfer) and the cross-linking of adjacent pentapeptides (transpeptidation), while monofunctional enzymes catalyze only the latter reaction. Although S. pneumoniae has six PBPs, only three (PBP1a, PBP2x, PBP2b) are major resistance determinants, with PBP1a being the only bifunctional enzyme. PBP1a plays a key role in septum formation during the cell division cycle and its modification is essential for the development of high-level resistance to penicillins and cephalosporins. The crystal structure of a soluble form of pneumococcal PBP1a (PBP1a*) has been solved to 2.6A and reveals that it folds into three domains. The N terminus contains a peptide from the glycosyltransfer domain bound to an interdomain linker region, followed by a central, transpeptidase domain, and a small C-terminal unit. An analysis of PBP1a sequences from drug-resistant clinical strains in light of the structure reveals the existence of a mutational hotspot at the entrance of the catalytic cleft that leads to the modification of the polarity and accessibility of the mutated PBP1a active site. The presence of this hotspot in all variants sequenced to date is of key relevance for the development of novel antibiotherapies for the treatment of beta-lactam-resistant pneumococcal strains.
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Affiliation(s)
- Carlos Contreras-Martel
- Institut de Biologie Structurale Jean-Pierre Ebel (CNRS/CEA/UJF), Laboratoire de Cristallographie Macromoléculaire, 41 rue Jules Horowitz, Grenoble 38027, France
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Granger D, Boily-Larouche G, Turgeon P, Weiss K, Roger M. Molecular characteristics of pbp1a and pbp2b in clinical Streptococcus pneumoniae isolates in Quebec, Canada. J Antimicrob Chemother 2005; 57:61-70. [PMID: 16282207 DOI: 10.1093/jac/dki401] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES To investigate the nature of the amino acid motifs found in penicillin-binding protein (PBP) 2b and PBP1a of penicillin-resistant Streptococcus pneumoniae isolates across Quebec (Canada), and to obtain preliminary information regarding the prevalence of these alterations. METHODS DNA sequences of pbp2b (codons 210-675) and pbp1a (codons 310-682) transpeptidase domains were determined and compared in 48 clinical isolates comprising 17 penicillin-susceptible (PSSP), 19 penicillin-intermediate (PISP) and 12 penicillin-resistant (PRSP) pneumococci. RESULTS The degree of diversity within PBP1a and PBP2b correlated with increased resistance to beta-lactam antibiotics. There were an average of 0.6 +/- 0.4 and 2.9 +/- 0.2 mutations in PSSP, 16.8 +/- 1.4 and 36.3 +/- 5.2 in PISP, and 18.7 +/- 2.5 and 51.4 +/- 1.3 in PRSP isolates compared with control penicillin-susceptible R6-PBP2b and R6-PBP1a sequences, respectively. At least seven PBP2b and six PBP1a distinct amino acid profiles were identified among intermediate or resistant strains isolated in Quebec. The pattern of distribution of the PBPs' altered amino acids differs from that of other countries, with pneumococci isolates from Quebec showing a unique genetic signature. CONCLUSION This study will serve as a basis for future monitoring of genetic changes associated with the emergence and spread of beta-lactam resistance in Quebec, Canada.
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Affiliation(s)
- Dominic Granger
- Laboratoire d'Immunogénétique, Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Hôpital Notre-Dame du CHUM, 1560 rue Sherbrooke est, Montréal, Québec, Canada
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McEllistrem MC, Adams JM, Visweswaran S, Khan SA. Detection of Very High–Level Penicillin-Resistant Variants of the Tennessee23F-4 Clone Via Single and Serial Transformations with Four Serotype 19A International Pneumococcal Clones. Microb Drug Resist 2005; 11:271-8. [PMID: 16201931 DOI: 10.1089/mdr.2005.11.271] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In the United States, penicillin-resistant variants of the Tennessee (Tenn) (23 F)-4 clone account for a substantial proportion of the very-high-level penicillin-resistant (MIC 8 microg/ml) infections in the 7-valent pneumococcal protein conjugate vaccine (PCV 7) era. Serotype 19 A strains account for an increasing proportion of penicillin-nonsusceptible Streptococcus pneumoniae infections. Sequential transformations of the Tenn (23 F)-4 clone (penicillin MIC 0.1 microg/ml) were performed with four penicillin-nonsusceptible serotype 19 A international clones (penicillin MIC): S. Africa (19 A)-7 (0.5 microg/ml), Hungary (19 A)-6 (2 microg/ml), Slovakia (19 A)-11 (8 microg/ml), and South Africa (19 A)-13 (8 microg/ml). Fifty-two transformants were characterized by MICs, serogroup-specific PCR, pbp PCR restriction profile and sequence, psp A PCR restriction profile, and erm/mef PCR. A subset was analyzed with multilocus sequence typing (MLST) and pulsed-field gel electrophoresis. Serotype 23 F transformants with penicillin MIC >or= 8 microg/ml were detected through a single transformation with the Hungary (19 A)-6 clone or serial transformations using two to three different clones. Forty-four percent (14/32) of the transformants incorporated >or=1 new MLST allele. Using encapsulated donors, very-high-level penicillin resistant variants of the Tenn (23 F)-4 clone were detected. In addition to detecting stepwise increases in penicillin MIC, a 12-fold increase in penicillin MIC was achieved through a single transformation. This large increase in MIC may explain why this clone is commonly associated with very-high-level resistance in natural populations. Recombination within the MLST housekeeping genes was commonly detected in the transformants that had acquired penicillin resistance.
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Granger D, Boily-Larouche G, Turgeon P, Weiss K, Roger M. Genetic analysis of pbp2x in clinical Streptococcus pneumoniae isolates in Quebec, Canada. J Antimicrob Chemother 2005; 55:832-9. [PMID: 15872046 DOI: 10.1093/jac/dki118] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
OBJECTIVES To investigate the nature of the amino acid motifs found in penicillin-binding protein (PBP) 2x of penicillin-resistant Streptococcus pneumoniae isolates across the province of Quebec (Canada), and to obtain preliminary information regarding the prevalence of these alterations. METHODS The pbp2x genomic region encompassing codons 178-703, which includes the entire region of the transpeptidase domain, was sequenced and compared for 52 clinical isolates comprising 20 penicillin-susceptible (PSSP), 20 penicillin-intermediate (PISP) and 12 penicillin-resistant (PRSP) pneumococci. RESULTS The degree of diversity within PBP2x correlated with increased resistance to beta-lactam antibiotics. There were an average of 5.0 +/- 1.8 mutations in PSSP, 37.9 +/- 4.4 in PISP, and 63.0 +/- 2.0 in PRSP isolates when compared with the control penicillin-susceptible strain R6. At least six distinct amino acid profiles were identified among PISP strains isolated in Quebec. In contrast, all PRSP isolates shared a similar pattern of altered amino acids compared with the sequence from susceptible strains. CONCLUSIONS These data will be useful in future studies to monitor the genetic changes associated with the emergence and spread of beta-lactam resistance in Quebec.
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Affiliation(s)
- Dominic Granger
- Laboratoire d'immunogénétique, Centre de Recherche du Centre Hospitalier de l'Université de Montréal, Montréal, Canada
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Woodford N. Biological counterstrike: antibiotic resistance mechanisms of Gram-positive cocci. Clin Microbiol Infect 2005; 11 Suppl 3:2-21. [PMID: 15811020 DOI: 10.1111/j.1469-0691.2005.01140.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The development of antibiotic resistance by bacteria is an evolutionary inevitability, a convincing demonstration of their ability to adapt to adverse environmental conditions. Since the emergence of penicillinase-producing Staphylococcus aureus in the 1940s, staphylococci, enterococci and streptococci have proved themselves adept at developing or acquiring mechanisms that confer resistance to all clinically available antibacterial classes. The increasing problems of methicillin-resistant S. aureus and coagulase-negative staphylococci (MRSA and MRCoNS), glycopeptide-resistant enterococci and penicillin-resistant pneumococci in the 1980s, and recognition of glycopeptide-intermediate S. aureus in the 1990s and, most recently, of fully vancomycin-resistant isolates of S. aureus have emphasised our need for new anti-Gram-positive agents. Antibiotic resistance is one of the major public health concerns for the beginning of the 21st century. The pharmaceutical industry has responded with the development of oxazolidinones, lipopeptides, injectable streptogramins, ketolides, glycylcyclines, second-generation glycopeptides and novel fluoroquinolones. However, clinical use of these novel agents will cause new selective pressures and will continue to drive the development of resistance. This review describes the various antibiotic resistance mechanisms identified in isolates of staphylococci, enterococci and streptococci, including mechanisms of resistance to recently introduced anti-Gram-positive agents.
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Affiliation(s)
- N Woodford
- Antibiotic Resistance Monitoring and Reference Laboratory, Centre for Infections, Health Protection Agency, London NW9 5HT, UK.
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Kosowska K, Jacobs MR, Bajaksouzian S, Koeth L, Appelbaum PC. Alterations of penicillin-binding proteins 1A, 2X, and 2B in Streptococcus pneumoniae isolates for which amoxicillin MICs are higher than penicillin MICs. Antimicrob Agents Chemother 2004; 48:4020-2. [PMID: 15388470 PMCID: PMC521876 DOI: 10.1128/aac.48.10.4020-4022.2004] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Penicillin-binding proteins (PBPs) of 15 selected penicillin- and amoxicillin-resistant Streptococcus pneumoniae isolates (MICs of 2 to 8 and 8 to 16 microg/ml, respectively) were studied. In addition to typical changes in PBPs 1A and 2X, these strains had 10 unique changes in PBP 2B, including a (618)A-G substitution, which may be the key alteration associated with amoxicillin resistance.
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Affiliation(s)
- K Kosowska
- Laboratory Specialists, Inc., 1651 A Crossings Parkway, Westlake, OH 44145, USA
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Gums JG, Epstein BJ. Update on Resistance among Respiratory Tract Pathogens: Results of the Antimicrobial Resistance Management Program. Hosp Pharm 2004. [DOI: 10.1177/001857870403901106] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Purpose This update from the Antimicrobial Resistance Management (ARM) Program reports surveillance data for Streptrococcus pneumoniae and Haemophilus influenzae isolates from 1994 to 2002. Methods Antibiograms and sensitivity reports submitted to the ARM program database were reviewed for resistance to commonly prescribed antibiotics Results Nationally S. pneumoniae resistance to penicillin was 37.4% (n = 37,688); to erythromycin, 29.6% (n = 18,774); and to clindamycin, 9.9% (n = 5510). Resistance to cefotaxime was 25.5% (n = 10,527) and 16.8% to ceftriaxone (26,594). For H. influenzae, resistance to cefotaxime was 4.3% (n = 4,927) and to ceftriaxone 1% (n = 10,353), a difference seen largely in the Northeast. Conclusions Resistance to penicillin appears to have reached a plateau above 40%; however, sparing of beta-lactam antibiotics may occur at the expense of other agents (ie, macrolides). Clindamycin remains active against penicillin-resistant S. pneumoniae (PRSP), but use of agents with antianaerobic properties is discouraged. The ARM program suggests important differences between cefotaxime and ceftriaxone.
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Affiliation(s)
- John G. Gums
- Departments of Pharmacy Practice and Community Health and Family Medicine, Colleges of Pharmacy and Medicine; University of Florida, Gainesville, FL
| | - Benjamin J. Epstein
- Internal Medicine Resident, North Florida/South Georgia Veterans Affairs Health System; currently Postdoctoral Fellow, Departments of Pharmacy Practice and Community Health and Family Medicine, Colleges of Pharmacy and Medicine, University of Florida, Gainesville, FL
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45
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Schrag SJ, McGee L, Whitney CG, Beall B, Craig AS, Choate ME, Jorgensen JH, Facklam RR, Klugman KP. Emergence of Streptococcus pneumoniae with very-high-level resistance to penicillin. Antimicrob Agents Chemother 2004; 48:3016-23. [PMID: 15273115 PMCID: PMC478489 DOI: 10.1128/aac.48.8.3016-3023.2004] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Penicillin resistance threatens the treatment of pneumococcal infections. We used sentinel hospital surveillance (1978 to 2001) and population-based surveillance (1995 to 2001) in seven states in the Active Bacterial Core surveillance of the Emerging Infections Program Network to document the emergence in the United States of invasive pneumococcal isolates with very-high-level penicillin resistance (MIC > or = 8 microg/ml). Very-high-level penicillin resistance was first detected in 1995 in multiple pneumococcal serotypes in three regions of the United States. The prevalence increased from 0.56% (14 of 2,507) of isolates in 1995 to 0.87% in 2001 (P = 0.03), with peaks in 1996 and 2000 associated with epidemics in Georgia and Maryland. For a majority of the strains the MICs of amoxicillin (91%), cefuroxime (100%), and cefotaxime (68%), were > or =8 microg/ml and all were resistant to at least one other drug class. Pneumonia (50%) and bacteremia (36%) were the most common clinical presentations. Factors associated with very highly resistant infections included residence in Tennessee, age of <5 or > or =65 years, and resistance to at least three drug classes. Hospitalization and case fatality rates were not higher than those of other pneumococcal infection patients; length of hospital stay was longer, controlling for age. Among the strains from 2000 and 2001, 39% were related to Tennessee(23F)-4 and 35% were related to England(14-)9. After the introduction of the pneumococcal conjugate vaccine, the incidence of highly penicillin resistant infections decreased by 50% among children <5 years of age. The emergence, clonality, and association of very-high-level penicillin resistance with multiple drug resistance requires further monitoring and highlights the need for novel agents active against the pneumococcus.
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Affiliation(s)
- Stephanie J Schrag
- Division of Bacterial and Mycotic Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA
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Baek JY, Ko KS, Oh WS, Jung SI, Kim YS, Chang HH, Lee H, Kim SW, Peck KR, Lee NY, Song JH. Unique variations of pbp2b sequences in penicillin-nonsusceptible Streptococcus pneumoniae isolates from Korea. J Clin Microbiol 2004; 42:1746-50. [PMID: 15071038 PMCID: PMC387593 DOI: 10.1128/jcm.42.4.1746-1750.2004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
pbp2b gene alterations were analyzed in 102 clinical isolates of Streptococcus pneumoniae (30 penicillin susceptible, 23 intermediate, and 49 resistant) from Korea. On the basis of PBP2B amino acid sequences, penicillin-nonsusceptible isolates of S. pneumoniae belonged to six groups, and 76% of the isolates in groups I to IV showed the same divergent block of amino acid alterations. Thirteen isolates (group II) also possessed a divergent block that was identical to that of Streptococcus oralis. The pbp2b genes of most Korean isolates showed novel mosaic mutations due to horizontal gene transfer. The Thr252 --> Ala substitution, previously thought to be associated only with penicillin-nonsusceptible strains, was also found in three penicillin-susceptible strains. On the basis of their pbp2b nucleotide sequences, all penicillin-nonsusceptible isolates can be detected by multiplex PCR, which can be used as a novel method for detection of antibiotic-resistant pneumococcal strains in clinical specimens.
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Affiliation(s)
- Jin Yang Baek
- Asian-Pacific Research Foundation for Infectious Diseases,, Seoul 135-710, Korea
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47
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Sanbongi Y, Ida T, Ishikawa M, Osaki Y, Kataoka H, Suzuki T, Kondo K, Ohsawa F, Yonezawa M. Complete sequences of six penicillin-binding protein genes from 40 Streptococcus pneumoniae clinical isolates collected in Japan. Antimicrob Agents Chemother 2004; 48:2244-50. [PMID: 15155228 PMCID: PMC415593 DOI: 10.1128/aac.48.6.2244-2250.2004] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2003] [Revised: 11/20/2003] [Accepted: 02/21/2004] [Indexed: 11/20/2022] Open
Abstract
All six penicillin-binding protein (PBP) genes, namely, pbp1a, pbp1b, pbp2a, pbp2b, pbp2x, and pbp3, of 40 Streptococcus pneumoniae clinical isolates, including penicillin-resistant S. pneumoniae isolates collected in Japan, were completely sequenced. The MICs of penicillin for these strains varied between 0.015 and 8 microg/ml. In PBP 2X, the Thr550Ala mutation close to the KSG motif was observed in only 1 of 40 strains, whereas the Met339Phe mutation in the STMK motif was observed in six strains. These six strains were highly resistant (MICs >/= 2 microg/ml) to cefotaxime. The MICs of cefotaxime for 27 strains bearing the Thr338Ala mutation tended to increase, but the His394Leu mutation next to the SSN motif did not exist in these strains. In PBP 2B, the Thr451Ala/Phe/Ser and Glu481Gly mutations close to the SSN motif were observed in 24 strains, which showed penicillin resistance and intermediate resistance, and the Thr624Gly mutation close to the KTG motif was observed in 2 strains for which the imipenem MIC (0.5 microg/ml) was the highest imipenem MIC detected. In PBP 1A, the Thr371Ser/Ala mutation in the STMK motif was observed in all 13 strains for which the penicillin MICs were >/=1 microg/ml. In PBP 2A, the Thr411Ala mutation in the STIK motif was observed in one strain for which with the cefotaxime MIC (8 microg/ml) was the highest cefotaxime MIC detected. On the other hand, in PBPs 1B and 3, no mutations associated with resistance were observed. The results obtained here support the concept that alterations in PBPs 2B, 2X, and 1A are mainly involved in S. pneumoniae resistance to beta-lactam antibiotics. Our findings also suggest that the Thr411Ala mutation in PBP 2A may be associated with beta-lactam resistance.
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Affiliation(s)
- Yumiko Sanbongi
- Pharmaceutical Research Department, Meiji Seika Kaisha Ltd., 760 Morooka-cho, Kohoku-ku, Yokohama 222-8567, Japan.
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48
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Pagliero E, Chesnel L, Hopkins J, Croizé J, Dideberg O, Vernet T, Di Guilmi AM. Biochemical characterization of Streptococcus pneumoniae penicillin-binding protein 2b and its implication in beta-lactam resistance. Antimicrob Agents Chemother 2004; 48:1848-55. [PMID: 15105143 PMCID: PMC400559 DOI: 10.1128/aac.48.5.1848-1855.2004] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2003] [Revised: 12/14/2003] [Accepted: 01/29/2004] [Indexed: 11/20/2022] Open
Abstract
Extensive use of beta-lactam antibiotics has led to the selection of pathogenic streptococci resistant to beta-lactams due to modifications of the penicillin-binding proteins (PBPs). PBP2b from Streptococcus pneumoniae is a monofunctional (class B) high-molecular-weight PBP catalyzing the transpeptidation between adjacent stem peptides of peptidoglycan. The transpeptidase domain of PBP2b isolated from seven clinical resistant (CR) strains contains 7 to 44 amino acid changes over the sequence of PBP2b from the R6 beta-lactam-sensitive strain. We show that the extracellular soluble domains of recombinant PBP2b proteins (PBP2b*) originating from these CR strains have an in vitro affinity for penicillin G that is reduced by up to 99% from that of the R6 strain. The Thr446Ala mutation is always observed in CR strains and is close to the key conserved motif (S(443)SN). The Thr446Ala mutation in R6 PBP2b* displays a 60% reduction in penicillin G affinity in vitro compared to that for the wild-type protein. A recombinant R6 strain expressing the R6 PBP2b Thr446Ala mutation is twofold less sensitive to piperacillin than the parental S. pneumoniae strain. Analysis of the Thr446Ala mutation in the context of the PBP2b CR sequences revealed that its influence depends upon the presence of other unidentified mutations.
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Affiliation(s)
- Estelle Pagliero
- Laboratoire d'Ingénierie des Macromolécules, Institut de Biologie Structurale Jean-Pierre Ebel (CEA-CNRS UMR 5075-UJF), 38027 Grenoble Cedex 1, France
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Usui H, Takao A, Nakayama A, Nagashima H, Sasaki F, Maeda N, Ishibashi K. Detection of penicillin-binding protein 2b gene alteration in Streptococcus mitis by polymerase chain reaction. J Infect Chemother 2004; 10:19-24. [PMID: 14991513 DOI: 10.1007/s10156-003-0291-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2003] [Accepted: 11/17/2003] [Indexed: 10/26/2022]
Abstract
Three isolates of beta-lactam-resistant streptococci from the saliva of healthy adults were identified as Streptococcus mitis. Minimum inhibitory concentrations (MICs) were 2 to 4 micro g/ml for ampicillin (ABPC) and 64 to more than 128 micro g/ml for cefaclor (CCL). To determine the position of base alterations of the penicillin-binding protein 2b ( pbp2b) gene, upstream primers containing possible mutation points were designed, and used for polymerase chain reaction (PCR), together with a downstream primer. Alterations adjacent to the conserved motifs of the pbp2b gene were apparent. DNA sequencing data indicated replacements in deduced amino acid sequences in all resistant isolates: from threonine to alanine just after the serine-serine-asparagine (SSN) motif, and from alanine to glycine two residues downstream of the lysine-threonine-glycine (KTG) motif. These changes were the same as those in penicillin-resistant Streptococcus pneumoniae (PRSP), suggesting importance for the enzymatic activity of the protein. Thus, Beta-lactam susceptibility of S. mitis may be partially predicted by PCR using our primer set for pbp2b.
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Affiliation(s)
- Hiroyuki Usui
- Second Department of Oral and Maxillofacial Surgery, Tsurumi University School of Dental Medicine, Yokohama, Japan.
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Karlowsky JA, Jones ME, Draghi DC, Sahm DF. Clinical isolates of Streptococcus pneumoniae with different susceptibilities to ceftriaxone and cefotaxime. Antimicrob Agents Chemother 2004; 47:3155-60. [PMID: 14506024 PMCID: PMC201161 DOI: 10.1128/aac.47.10.3155-3160.2003] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ceftriaxone and cefotaxime are extended-spectrum cephalosporins previously demonstrated to possess very similar in vitro activities against Streptococcus pneumoniae. Anecdotal reports of isolates with divergent in vitro susceptibilities to ceftriaxone and cefotaxime have been published. To determine the prevalence of pneumococcal isolates with divergent ceftriaxone and cefotaxime susceptibilities, we tested 1,000 clinical isolates collected by U.S. laboratories in 2001-2002 by broth microdilution and E-test. The percentages of isolates susceptible to ceftriaxone and cefotaxime were significantly different by both broth microdilution (98.6 and 96.6%, respectively; P < 0.05) and E-test (98.3 and 95.8%; P < 0.001). The differences observed were due solely to the activities of the two agents against penicillin-resistant isolates. Twenty-six of 188 penicillin-resistant isolates (13.8%) demonstrated different ceftriaxone and cefotaxime MIC interpretative phenotypes when tested by broth microdilution; 18 isolates were concurrently ceftriaxone susceptible and cefotaxime intermediate, 6 were ceftriaxone intermediate and cefotaxime resistant, and 2 were ceftriaxone susceptible and cefotaxime resistant (1.1% of penicillin-resistant isolates; 0.2% of all isolates tested). Sixteen of the 26 isolates (65%) were from southern U.S. states. The 26 isolates had serogroups and serotypes (6, 9, 14, 19, and 23) commonly associated with penicillin-resistant isolates; SmaI pulsed-field gel electrophoresis identified 18 isolates (69%) dispersed among five subtype groups and 8 isolates that were unrelated to any of the other isolates. We conclude that certain isolates of penicillin-resistant pneumococci are less susceptible to cefotaxime than to ceftriaxone and that these isolates are not the result of the spread of a single clone. Whether such isolates have increased in prevalence over time remains unknown.
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