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Zhang T, Xu X, Xu CF, Bilya SR, Xu W. Mechanical ventilation-associated pneumonia caused by Acinetobacter baumannii in Northeast China region: analysis of genotype and drug resistance of bacteria and patients' clinical features over 7 years. Antimicrob Resist Infect Control 2021; 10:135. [PMID: 34526127 PMCID: PMC8444615 DOI: 10.1186/s13756-021-01005-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 09/01/2021] [Indexed: 11/22/2022] Open
Abstract
Objective To investigate the clinical features and outcomes of patients with mechanical ventilation-associated pneumonia (VAP) caused by Acinetobacter baumannii (Ab), and to characterize the drug resistance of pathogenic strains and carbapenem resistance-associated genes. Methods Clinical data were collected from the PICU of Shengjing Hospital. Patients who met the diagnostic criteria of VAP and for whom Ab was a pathogen were selected as study participants. The patients were divided into carbapenem-resistant A. baumannii (CRAB) and carbapenem-sensitive A. baumannii (CSAB) groups. The genes closely associated with Ab resistance to carbapenems and the efflux pump-related genes were detected by real-time polymerase chain reaction, and results compared between the two groups. Results The total mechanical ventilation time and the administration time of antibiotics after a diagnosis of Ab infection were significantly higher in the CRAB group. And the CRAB group strains were only sensitive to amikacin, cephazolin, compound sulfamethoxazole, and tigecycline. Genetic test results indicated that IPM expression was not significantly different between two groups. The OXA-51 and OXA-23 in the CRAB group was markedly higher than that in the CSAB group, while OXA-24 expression was markedly lower. The expression of AdeABC and AdeFGH was significantly greater in the CRAB compared to CSAB group. Conclusion In pediatric patients with VAP caused by Ab infection, the detection rate of CRAB strains is far higher than that of CSAB strains; The abnormal expression of β-lactamase-producing genes (OXA-23, OXA-24, and OXA-51) and efflux pump-related genes (AdeABC and AdeFGH) is closely related to the production of CRAB.
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Affiliation(s)
- Tao Zhang
- Department of Pediatrics, Shengjing Hospital of China Medical University, No. 36, SanHao Street, Shenyang City, 110004, Liaoning Province, People's Republic of China
| | - Xiao Xu
- Department of Pediatrics, Shengjing Hospital of China Medical University, No. 36, SanHao Street, Shenyang City, 110004, Liaoning Province, People's Republic of China
| | - Cai-Fang Xu
- Department of Pediatrics, Shengjing Hospital of China Medical University, No. 36, SanHao Street, Shenyang City, 110004, Liaoning Province, People's Republic of China
| | - Salisu Rabiu Bilya
- Department of Pediatrics, Shengjing Hospital of China Medical University, No. 36, SanHao Street, Shenyang City, 110004, Liaoning Province, People's Republic of China
| | - Wei Xu
- Department of Pediatrics, Shengjing Hospital of China Medical University, No. 36, SanHao Street, Shenyang City, 110004, Liaoning Province, People's Republic of China.
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2
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Bouharkat B, Tir Touil A, Mullié C, Chelli N, Meddah B. Bacterial ecology and antibiotic resistance mechanisms of isolated resistant strains from diabetic foot infections in the north west of Algeria. J Diabetes Metab Disord 2020; 19:1261-1271. [PMID: 33553027 PMCID: PMC7843819 DOI: 10.1007/s40200-020-00639-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Accepted: 09/17/2020] [Indexed: 01/10/2023]
Abstract
BACKGROUND In front of the polymorphic bacterial ecology and antibiotic resistance in diabetic patients with foot infections and good patient care, collaboration between clinicians and microbiologists is needed to improve assessment and management of patients with this pathology. OBJECTIVE This study was designed to characterize the bacterial ecology of diabetic foot infection (DFIs) and to determine the different mechanisms of resistance involved. METHODS In this study bacterial strains and antibiotic resistance profiles were determined from diabetic foot infections patients (n = 117). The identification of resistance mechanisms, such as penicillinase and/or extended-spectrum β-lactamase production (ESBL), methicillin-resistant Staphylococcus aureus (MRSA) and efflux pump over-expression were performed. RESULTS A high prevalence of Gram-negative bacteria (61%) with Escherichia coli, and other Enterobacteriaceae and Pseudomonas aeruginosa being the predominant isolates. Gram positive bacteria mainly represented by Staphylococcus aureus accounted for 39% of the isolates. 93.5% of the Enterobacteriaceae were resistant to, at least, one molecule in the β-lactam family, while the majority of the Staphylococci were resistant to penicillin G and tetracycline (93.3% and 71.7%). The majority of non-fermenting Gram negative bacteria were also resistant to fluoroquinolones. β-lactamase detection tests revealed the presence of extended-spectrum β-lactamase in 43.5% of the Enterobacteriaceae, while methicillin-resistant Staphylococcus aureus represented 18.2% of the isolates. Additionally, 50.9% of non-fermenting Gram negative bacteria were overproducing efflux pumps. CONCLUSION All Acinetobacter Baumannii were Multidrug-Resistant (MDR), as the majority of Staphylococci, and Enterobacteriaceae. These results should be taken into account by the clinician in the prescription of probabilistic antibiotic therapy in this context.
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Affiliation(s)
- Bakhta Bouharkat
- Laboratoire de Bioconversion, Génie Microbiologique et Sécurité Sanitaire, Faculté des Sciences de la Nature et de la vie, Université Mustapha Stambouli, 305 Route de Mamounia, 29000 Mascara, BP Algeria
| | - Aicha Tir Touil
- Laboratoire de Bioconversion, Génie Microbiologique et Sécurité Sanitaire, Faculté des Sciences de la Nature et de la vie, Université Mustapha Stambouli, 305 Route de Mamounia, 29000 Mascara, BP Algeria
| | - Catherine Mullié
- Laboratoire AGIR (Agents Infectieux, Résistance et Chimiothérapie) EA 4294, Université de Picardie Jules Verne, UFR de Pharmacie, 1 rue des Louvels, 80037 Amiens Cedex 1, France
| | - Nadia Chelli
- Laboratoire de Bioconversion, Génie Microbiologique et Sécurité Sanitaire, Faculté des Sciences de la Nature et de la vie, Université Mustapha Stambouli, 305 Route de Mamounia, 29000 Mascara, BP Algeria
| | - Boumediene Meddah
- Laboratoire de Bioconversion, Génie Microbiologique et Sécurité Sanitaire, Faculté des Sciences de la Nature et de la vie, Université Mustapha Stambouli, 305 Route de Mamounia, 29000 Mascara, BP Algeria
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3
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Efflux pumps as interventions to control infection caused by drug-resistance bacteria. Drug Discov Today 2020; 25:2307-2316. [PMID: 33011344 DOI: 10.1016/j.drudis.2020.09.028] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2020] [Revised: 08/06/2020] [Accepted: 09/24/2020] [Indexed: 12/30/2022]
Abstract
Antibiotic resistance has become a global concern for healthcare workers and physicians. Efflux pumps are one of the major mechanisms of resistance. Hence, we describe examples of natural efflux pump inhibitors used to combat antibiotic resistance.
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4
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Salmani A, Mohsenzadeh M, Pirouzi A, Khaledi A. A comprehensive meta-analysis of antibiotic resistance pattern among biofilm production strains of Acinetobacter baumannii recovered from clinical specimens of patients. GENE REPORTS 2020. [DOI: 10.1016/j.genrep.2020.100664] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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5
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Choi J, Baek J, Kweon D, Ko KS, Yoon H. Rapid determination of carbapenem resistance by low-cost colorimetric methods: Propidium Iodide and alamar blue staining. J Microbiol 2020; 58:415-421. [PMID: 32221821 DOI: 10.1007/s12275-020-9549-x] [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: 11/15/2019] [Revised: 02/04/2020] [Accepted: 02/14/2020] [Indexed: 01/03/2023]
Abstract
Carbapenems are a class of β-lactam antibiotics with a broad antimicrobial activity spectrum. Owing to their sturdy structures resistant to most β-lactamases, they have been regarded as one of the last-resort antibiotics for combating multidrugresistant bacterial infections. However, the emergence of carbapenem resistance increases predominantly in nosocomial pathogens. To prevent spread of carbapenem resistance in early stages, it is imperative to develop rapid diagnostic tests that will substantially reduce the time and cost in determining carbapenem resistance. Thus, we devised a staining-based diagnostic method applicable to three different Gram-negative pathogens of Acinetobacter baumannii, Escherichia coli, and Klebsiella pneumoniae, all with the high potential to develop carbapenem resistance. Regardless of the resistance mechanisms presented by bacterial species and strains, double staining with propidium iodide (PI) and alamar blue (AB) identified resistant bacteria with an average sensitivity of 95.35%, 7 h after imipenem treatments in 343 clinical isolates. Among the three species tested, A. baumannii showed the highest diagnostic sensitivity of 98.46%. The PI and ABmediated staining method could be a promising diagnostic method with high-throughput efficacy and low cost.
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Affiliation(s)
- Jiyoon Choi
- Department of Molecular Science and Technology, Ajou University, Suwon, 16499, Republic of Korea
| | - Jiwon Baek
- Department of Molecular Science and Technology, Ajou University, Suwon, 16499, Republic of Korea
| | - Daehyuk Kweon
- Department of Genetic Engineering and Center for Human Interface Nano Technology, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Kwan Soo Ko
- Department of Molecular Cell Biology, Sungkyunkwan University, School of Medicine, Suwon, 16419, Republic of Korea.,Asia-Pacific Research Foundation for Infectious Diseases, Seoul, 06367, Republic of Korea
| | - Hyunjin Yoon
- Department of Molecular Science and Technology, Ajou University, Suwon, 16499, Republic of Korea. .,Department of Applied Chemistry and Biological Engineering, Ajou University, Suwon, 16499, Republic of Korea.
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Yilmaz Ş, Hasdemir U, Aksu B, Altınkanat Gelmez G, Söyletir G. Alterations in AdeS and AdeR regulatory proteins in 1-(1-naphthylmethyl)-piperazine responsive colistin resistance of Acinetobacter baumannii. J Chemother 2020; 32:286-293. [PMID: 32131715 DOI: 10.1080/1120009x.2020.1735118] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Colistin resistant Acinetobacter baumannii strains are of great concern worldwide. However, the role of efflux pumps in colistin resistance needs to be elucidated. We investigated the changes in colistin MICs of 29 colistin resistant A. baumannii isolates in response to resistance-nodulation-division (RND)-type efflux pump inhibitor (EPI) and the alterations in AdeR and AdeS two-component regulatory proteins previously associated with the overproduction of AdeAB. The EPI, 1-(1-naphthylmethyl)-piperazine (NMP), led to significant reductions in colistin MICs. At least one of the following amino acid substitutions was found in AdeS proteins from 18 of the isolates: L172P, A94V, V27I, V32I, G186V, and G164A. Besides, A136V and V120I alterations were identified in AdeR from five isolates. Therefore, EPI-responsive colistin resistance in our isolates is most likely due to the action of an RND-type efflux system. The underlying mechanism of resistance might be the result of certain AdeRS alterations, leading to AdeAB overexpression.
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Affiliation(s)
- Şerife Yilmaz
- Department of Medical Microbiology, Karabuk University Training and Research Hospital, Karabuk, Turkey
| | - Ufuk Hasdemir
- Department of Medical Microbiology, Marmara University, School of Medicine, Istanbul, Turkey
| | - Burak Aksu
- Department of Medical Microbiology, Marmara University, School of Medicine, Istanbul, Turkey
| | | | - Güner Söyletir
- Department of Medical Microbiology, Marmara University, School of Medicine, Istanbul, Turkey
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7
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Insights into the Periplasmic Proteins of Acinetobacter baumannii AB5075 and the Impact of Imipenem Exposure: A Proteomic Approach. Int J Mol Sci 2019; 20:ijms20143451. [PMID: 31337077 PMCID: PMC6679007 DOI: 10.3390/ijms20143451] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 07/09/2019] [Accepted: 07/10/2019] [Indexed: 02/08/2023] Open
Abstract
Carbapenem-resistant Acinetobacter baumannii strains cause life-threatening infections due to the lack of therapeutic options. Although the main mechanisms underlying antibiotic-resistance have been extensively studied, the general response to maintain bacterial viability under antibiotic exposure deserves to be fully investigated. Since the periplasmic space contains several proteins with crucial cellular functions, besides carbapenemases, we decided to study the periplasmic proteome of the multidrug-resistant (MDR) A. baumannii AB5075 strain, grown in the absence and presence of imipenem (IMP). Through the proteomic approach, 65 unique periplasmic proteins common in both growth conditions were identified: eight proteins involved in protein fate, response to oxidative stress, energy metabolism, antibiotic-resistance, were differentially expressed. Among them, ABUW_1746 and ABUW_2363 gene products presented the tetratricopeptide repeat motif, mediating protein-protein interactions. The expression switch of these proteins might determine specific protein interactions to better adapt to changing environmental conditions. ABUW_2868, encoding a heat shock protein likely involved in protection against oxidative stress, was upregulated in IMP-exposed bacteria. Accordingly, the addition of periplasmic proteins from A. baumannii cultured with IMP increased bacterial viability in an antioxidant activity assay. Overall, this study provides the first insights about the composition of the periplasmic proteins of a MDR A. baumannii strain, its biological response to IMP and suggests possible new targets to develop alternative antibiotic drugs.
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8
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Long D, Zhu LL, Du FL, Xiang TX, Wan LG, Wei DD, Zhang W, Liu Y. Phenotypical profile and global transcriptomic profile of Hypervirulent Klebsiella pneumoniae due to carbapenemase-encoding plasmid acquisition. BMC Genomics 2019; 20:480. [PMID: 31185888 PMCID: PMC6558890 DOI: 10.1186/s12864-019-5705-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Accepted: 04/16/2019] [Indexed: 12/13/2022] Open
Abstract
Background Plasmids play an vital role in driving the rapid global spread of antimicrobial resistance and adaptation to changing ambient conditions. It has been suggested that the presence of plasmids can pose tremendous impacts on the host physiology. However, little is known regarding the contributions of carbapenemase-encoding plasmid carriage on the physiology and pathogenicity of hypervirulent K. pneumoniae (hvKP). Results Here we performed a transcriptomic analysis of hvKP with or without carbapenemase-encoding plasmid p24835-NDM5. The results had shown 683 genes with differential expression (false discovery rate, ≤0.001; > 2-fold change), of which 107 were up-regulated and 576 were down-regulated. Gene groups with functions relating to carbohydrate metabolism and multidrug efflux system were increased in genes with increased expression, and those relating to capsule biosynthesis and virulence factors were increased in the genes with decreased expression. In agreement with these changes, survival rate of TfpNDM-hvKP in the presence of normal human serum decreased, and competitive index (CI values) indicated significant fitness defects in the plasmid-carrying hvKP strain when co-cultured with its plasmid-free isogenic ancestor and the ATCC control. Moreover, the p24835-NDM5-containing hvKP strain retained its high neutrophil-mediated phagocytosis and murine lethality. Conclusion These data indicate that hvKP responds to carbapenemase-encoding plasmid by altering the expression of genes involved in carbohydrate metabolism, antibiotic resistance, capsule biosynthesis and virulence expression. Apart from antibiotic resistance selective advantages, carbapenemase-encoding plasmid carriage may also lead to virulence change or adaption to specific habitats in hvKP strain. Electronic supplementary material The online version of this article (10.1186/s12864-019-5705-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Dan Long
- Department of Clinical Microbiology, First Affiliated Hospital of Nanchang University, Nanchang University, Yong wai zheng jie No. 17, Nanchang, 330006, People's Republic of China
| | - Lan-Lan Zhu
- Department of Respiratory, First Affiliated Hospital of Nanchang University, Nanchang University, Yong wai zheng jie No. 17, Nanchang, 330006, People's Republic of China
| | - Fang-Ling Du
- Department of Clinical Microbiology, First Affiliated Hospital of Nanchang University, Nanchang University, Yong wai zheng jie No. 17, Nanchang, 330006, People's Republic of China
| | - Tian-Xin Xiang
- Department of Clinical Microbiology, First Affiliated Hospital of Nanchang University, Nanchang University, Yong wai zheng jie No. 17, Nanchang, 330006, People's Republic of China
| | - La-Gen Wan
- Department of Clinical Microbiology, First Affiliated Hospital of Nanchang University, Nanchang University, Yong wai zheng jie No. 17, Nanchang, 330006, People's Republic of China
| | - Dan-Dan Wei
- Department of Clinical Microbiology, First Affiliated Hospital of Nanchang University, Nanchang University, Yong wai zheng jie No. 17, Nanchang, 330006, People's Republic of China
| | - Wei Zhang
- Department of Respiratory, First Affiliated Hospital of Nanchang University, Nanchang University, Yong wai zheng jie No. 17, Nanchang, 330006, People's Republic of China
| | - Yang Liu
- Department of Clinical Microbiology, First Affiliated Hospital of Nanchang University, Nanchang University, Yong wai zheng jie No. 17, Nanchang, 330006, People's Republic of China.
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9
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Hawkey PM, Warren RE, Livermore DM, McNulty CAM, Enoch DA, Otter JA, Wilson APR. Treatment of infections caused by multidrug-resistant Gram-negative bacteria: report of the British Society for Antimicrobial Chemotherapy/Healthcare Infection Society/British Infection Association Joint Working Party. J Antimicrob Chemother 2019. [PMID: 29514274 DOI: 10.1093/jac/dky027] [Citation(s) in RCA: 188] [Impact Index Per Article: 37.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The Working Party makes more than 100 tabulated recommendations in antimicrobial prescribing for the treatment of infections caused by multidrug-resistant (MDR) Gram-negative bacteria (GNB) and suggest further research, and algorithms for hospital and community antimicrobial usage in urinary infection. The international definition of MDR is complex, unsatisfactory and hinders the setting and monitoring of improvement programmes. We give a new definition of multiresistance. The background information on the mechanisms, global spread and UK prevalence of antibiotic prescribing and resistance has been systematically reviewed. The treatment options available in hospitals using intravenous antibiotics and in primary care using oral agents have been reviewed, ending with a consideration of antibiotic stewardship and recommendations. The guidance has been derived from current peer-reviewed publications and expert opinion with open consultation. Methods for systematic review were NICE compliant and in accordance with the SIGN 50 Handbook; critical appraisal was applied using AGREE II. Published guidelines were used as part of the evidence base and to support expert consensus. The guidance includes recommendations for stakeholders (including prescribers) and antibiotic-specific recommendations. The clinical efficacy of different agents is critically reviewed. We found there are very few good-quality comparative randomized clinical trials to support treatment regimens, particularly for licensed older agents. Susceptibility testing of MDR GNB causing infection to guide treatment needs critical enhancements. Meropenem- or imipenem-resistant Enterobacteriaceae should have their carbapenem MICs tested urgently, and any carbapenemase class should be identified: mandatory reporting of these isolates from all anatomical sites and specimens would improve risk assessments. Broth microdilution methods should be adopted for colistin susceptibility testing. Antimicrobial stewardship programmes should be instituted in all care settings, based on resistance rates and audit of compliance with guidelines, but should be augmented by improved surveillance of outcome in Gram-negative bacteraemia, and feedback to prescribers. Local and national surveillance of antibiotic use, resistance and outcomes should be supported and antibiotic prescribing guidelines should be informed by these data. The diagnosis and treatment of both presumptive and confirmed cases of infection by GNB should be improved. This guidance, with infection control to arrest increases in MDR, should be used to improve the outcome of infections with such strains. Anticipated users include medical, scientific, nursing, antimicrobial pharmacy and paramedical staff where they can be adapted for local use.
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Affiliation(s)
- Peter M Hawkey
- Institute of Microbiology and Infection, University of Birmingham, Birmingham, UK
| | | | | | - Cliodna A M McNulty
- Microbiology Department, Gloucestershire Royal Hospital, Great Western Road, Gloucester GL1 3NN, UK
| | - David A Enoch
- Public Health England, Addenbrooke's Hospital, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK
| | | | - A Peter R Wilson
- Department of Microbiology and Virology, University College London Hospitals, London, UK
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10
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Frey M, Bobbala S, Karabin N, Scott E. Influences of nanocarrier morphology on therapeutic immunomodulation. Nanomedicine (Lond) 2018; 13:1795-1811. [PMID: 30084296 DOI: 10.2217/nnm-2018-0052] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Nanomaterials provide numerous advantages for the administration of therapeutics, particularly as carriers of immunomodulatory agents targeting specific immune cell populations during immunotherapy. While the physicochemical characteristics of nanocarriers have long been linked to their therapeutic efficacy and applications, focus has primarily been placed on assessing influences of size and surface chemistry. In addition to these materials properties, the nanostructure morphology, in other words, shape and aspect ratio, has emerged as an equally important feature of nanocarriers that can dictate mechanisms of endocytosis, biodistribution and degree of cytotoxicity. In this review, we will highlight how the morphological features of nanostructures influence the immune responses elicited during therapeutic immunomodulation.
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Affiliation(s)
- Molly Frey
- Interdisciplinary Biological Sciences Program, Northwestern University, Evanston, IL 60208, USA
| | - Sharan Bobbala
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Nicholas Karabin
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
| | - Evan Scott
- Interdisciplinary Biological Sciences Program, Northwestern University, Evanston, IL 60208, USA.,Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA.,Chemistry of Life Processes Institute, Northwestern University, Evanston, IL 60208, USA.,Simpson Querrey Institute, Northwestern University, Chicago, IL 60611, USA.,Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, IL 60611, USA
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11
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Zhang Y, Li Z, He X, Ding F, Wu W, Luo Y, Fan B, Cao H. Overproduction of efflux pumps caused reduced susceptibility to carbapenem under consecutive imipenem-selected stress in Acinetobacter baumannii. Infect Drug Resist 2018; 11:457-467. [PMID: 29636625 PMCID: PMC5880185 DOI: 10.2147/idr.s151423] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
PURPOSE Acinetobacter baumannii is an important pathogen in the nosocomial infections worldwide. Combining with carbapenemases, efflux pumps and outer membrane proteins (OMPs) have been thought to affect the development of carbapenem resistance in A. baumannii. This study aimed to investigate the contributions of different efflux pumps and OMPs in developing carbapenem resistance in a clinical isolate of A. baumannii and reveal the possible mechanism of overproduction of main efflux pumps. PATIENTS AND METHODS In this study, an imipenem-susceptible clinical isolate was identified as A. baumannii and named SZE. Several common carbapenemases were detected by polymerase chain reaction (PCR). Imipenem-selected mutants were selected from SZE by serial subcultivations on Mueller-Hinton agar, and the minimum inhibitory concentration (MIC) was detected. Gene expressions of four families of efflux pumps, five OMPs, and blaOXA-51 were determined by reverse transcription quantitative PCR, and comparisons were made between SZE strain and the imipenem-selected mutants. The adeRS system in SZE and its mutant was sequenced and aligned. RESULTS Under consecutive imipenem-selected stress, the MIC to imipenem increased gradually from 0.125 μg/mL to 8 μg/mL. The effect of resistance inducement was almost neutralized when treated with an efflux pump inhibitor. The expression of efflux pumps, adeB, adeG, and adeJ, was increased by 6.9-, 4.0-, and 2.1-fold in mutants, respectively, compared to SZE. A single mutation (G to A) at position 58 was detected in the regulatory adeRS system and possibly upregulated the adeB expression, and then affected the carbapenem resistance in A. baumannii strains. CONCLUSION In conclusion, under consecutive imipenem-selected stress in vitro, A. baumannii strain evolved the ability to reduce susceptibility to a variety of antimicrobials by overproduction of efflux pumps. Especially, the resistance-nodulation-cell division super family and a nucleotide mutant in adeRS regulating system caused the overexpression of adeABC.
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Affiliation(s)
- Yanpeng Zhang
- Department of Microbiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, 510515, China
- Laboratory Department of the First Affiliated Hospital of Shenzhen University, Shenzhen, 518000, China
| | - Zhuocheng Li
- Laboratory Department of the First Affiliated Hospital of Shenzhen University, Shenzhen, 518000, China
| | - Xiaolong He
- Department of Microbiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, 510515, China
| | - Fanglin Ding
- Laboratory Department of the First Affiliated Hospital of Shenzhen University, Shenzhen, 518000, China
| | - Weiqing Wu
- Laboratory Department of the First Affiliated Hospital of Shenzhen University, Shenzhen, 518000, China
| | - Yong Luo
- Laboratory Department of the First Affiliated Hospital of Shenzhen University, Shenzhen, 518000, China
| | - Bing Fan
- Laboratory Department of the First Affiliated Hospital of Shenzhen University, Shenzhen, 518000, China
| | - Hong Cao
- Department of Microbiology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, 510515, China
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12
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Choi IS, Kim CM, Jang SJ. Screening antibiotics using an Hoechst 33342 dye-accumulation assay to detect efflux activity in Acinetobacter baumannii clinical isolates. ASIAN BIOMED 2018. [DOI: 10.1515/abm-2018-0010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Abstract
Background
Understanding the contribution of efflux pumps to the resistance of antibiotics is useful when considering strategies for antimicrobial therapy.
Objectives
To assess the role of efflux activity on the resistance of antibiotics commonly used in hospitals.
Methods
We analyzed the efflux activity of 120 clinical isolates of Acinetobacter baumannii using an Hoechst 33342 (H33342) dye-accumulation assay. We compared the indicators for efflux activity of susceptible and non-susceptible groups of each of 16 tested antibiotics. To determine the role of efflux activity on resistance to an antibiotic, we used 3 criteria based on the results of the H33342-accumulation assay.
Results
The evaluation suggests that efflux activity contributed to resistance to the following 11 antibiotics: cefepime, cefotaxime, ceftazidime, ciprofloxacin, gentamicin, imipenem, meropenem, piperacillin, piperacillin/tazobactam, ticarcillin/ clavulanic acid, and tigecycline. However, ampicillin/sulbactam, minocycline, and trimethoprim/sulfamethoxazole did not meet the criteria, suggesting resistance may not be mediated by efflux activity. A significant difference in efflux activity was observed between bacteria belonging to the multidrug-resistant Acinetobacter baumannii (MDRAB) group and those belonging to the non-MDRAB group.
Conclusions
Efflux activity may contribute to multidrug resistance and particularly resistance to numerous antibiotics used in hospitals. These antibiotics would be good candidates for combination therapeutic regimens consisting of an antibiotic and an efflux pump inhibitor as an adjuvant to combat drug efflux.
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Affiliation(s)
- In-Sun Choi
- Department of Laboratory Medicine , Chosun University Hospital , Gwangju , South Korea
| | - Choon-Mee Kim
- Premedical Science, College of Medicine , Chosun University Hospital , Gwangju , South Korea
| | - Sook-Jin Jang
- Department of Laboratory Medicine, College of Medicine , Chosun University Hospital , Gwangju , South Korea
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13
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Lin F, Xu Y, Chang Y, Liu C, Jia X, Ling B. Molecular Characterization of Reduced Susceptibility to Biocides in Clinical Isolates of Acinetobacter baumannii. Front Microbiol 2017; 8:1836. [PMID: 29018420 PMCID: PMC5622949 DOI: 10.3389/fmicb.2017.01836] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 09/07/2017] [Indexed: 12/11/2022] Open
Abstract
Active efflux is regarded as a common mechanism for antibiotic and biocide resistance. However, the role of many drug efflux pumps in biocide resistance in Acinetobacter baumannii remains unknown. Using biocide-resistant A. baumannii clinical isolates, we investigated the incidence of 11 known/putative antimicrobial resistance efflux pump genes (adeB, adeG, adeJ, adeT1, adeT2, amvA, abeD, abeM, qacE, qacEΔ1, and aceI) and triclosan target gene fabI through PCR and DNA sequencing. Reverse transcriptase quantitative PCR was conducted to assess the correlation between the efflux pump gene expression and the reduced susceptibility to triclosan or chlorhexidine. The A. baumannii isolates displayed high levels of reduced susceptibility to triclosan, chlorhexidine, benzalkonium, hydrogen peroxide, and ethanol. Most tested isolates were resistant to multiple antibiotics. Efflux resistance genes were widely distributed and generally expressed in A. baumannii. Although no clear relation was established between efflux pump gene expression and antibiotic resistance or reduced biocide susceptibility, triclosan non-susceptible isolates displayed relatively increased expression of adeB and adeJ whereas chlorhexidine non-susceptible isolates had increased abeM and fabI gene expression. Increased expression of adeJ and abeM was also demonstrated in multiple antibiotic resistant isolates. Exposure of isolates to subinhibitory concentrations of triclosan or chlorhexidine induced gene expression of adeB, adeG, adeJ and fabI, and adeB, respectively. A point mutation in FabI, Gly95Ser, was observed in only one triclosan-resistant isolate. Multiple sequence types with the major clone complex, CC92, were identified in high level triclosan-resistant isolates. Overall, this study showed the high prevalence of antibiotic and biocide resistance as well as the complexity of intertwined resistance mechanisms in clinical isolates of A. baumannii, which highlights the importance of antimicrobial stewardship and resistance surveillance in clinics.
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Affiliation(s)
- Fei Lin
- Sichuan Province College Key Laboratory of Structure-Specific Small Molecule Drugs, School of Pharmacy, Chengdu Medical College, Chengdu, Sichuan, China.,Non-coding RNA and Drug Discovery Key Laboratory of Sichuan Province, Chengdu Medical College, Chengdu, Sichuan, China
| | - Ying Xu
- Clinical Laboratory, the First Affiliated Hospital, Chengdu Medical College, Chengdu, Sichuan, China
| | - Yaowen Chang
- Sichuan Province College Key Laboratory of Structure-Specific Small Molecule Drugs, School of Pharmacy, Chengdu Medical College, Chengdu, Sichuan, China.,Non-coding RNA and Drug Discovery Key Laboratory of Sichuan Province, Chengdu Medical College, Chengdu, Sichuan, China
| | - Chao Liu
- Sichuan Province College Key Laboratory of Structure-Specific Small Molecule Drugs, School of Pharmacy, Chengdu Medical College, Chengdu, Sichuan, China.,Non-coding RNA and Drug Discovery Key Laboratory of Sichuan Province, Chengdu Medical College, Chengdu, Sichuan, China
| | - Xu Jia
- Non-coding RNA and Drug Discovery Key Laboratory of Sichuan Province, Chengdu Medical College, Chengdu, Sichuan, China
| | - Baodong Ling
- Sichuan Province College Key Laboratory of Structure-Specific Small Molecule Drugs, School of Pharmacy, Chengdu Medical College, Chengdu, Sichuan, China
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Bloodstream infections caused by Acinetobacter species with reduced susceptibility to tigecycline: clinical features and risk factors. Int J Infect Dis 2017; 62:26-31. [PMID: 28676346 DOI: 10.1016/j.ijid.2017.06.023] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 06/02/2017] [Accepted: 06/26/2017] [Indexed: 02/07/2023] Open
Abstract
INTRODUCTION During recent decades, the rates of multidrug resistance, including resistance to carbapenems, have increased dramatically among Acinetobacter species. Tigecycline has activity against multidrug-resistant Acinetobacter spp, including carbapenem-resistant isolates. However, reports of tigecycline-resistant Acinetobacter spp are emerging from different parts of the world. The purpose of this study was to evaluate potential risk factors associated with tigecycline non-susceptible Acinetobacter bacteremia. METHODS The medical records of 152 patients with Acinetobacter bacteremia attending Samsung Medical Center between January 2010 and December 2014 were reviewed. Non-susceptibility to tigecycline was defined as a minimum inhibitory concentration (MIC) of tigecycline ≥4μg/ml. Cases were patients with tigecycline non-susceptible Acinetobacter bacteremia and controls were those with tigecycline-susceptible Acinetobacter bacteremia. RESULTS Of the 152 patients included in the study, 61 (40.1%) had tigecycline non-susceptible Acinetobacter bacteremia (case group). These patients were compared to 91 patients with tigecycline-susceptible Acinetobacter bacteremia (control group). The case group showed high resistance to other antibiotics (>90%) except colistin (6.6%) and minocycline (9.8%) when compared to the control group, which exhibited relatively low resistance to other antibiotics (<50%). Multivariate analysis showed that recent exposure to corticosteroids (minimum 20mg per day for more than 5 days within 2 weeks) (adjusted odds ratio (OR) 2.887, 95% confidence interval (CI) 1.170-7.126) and carbapenems (within 2 weeks) (adjusted OR 4.437, 95% CI 1.970-9.991) were significantly associated with tigecycline non-susceptible Acinetobacter bacteremia. Although prior exposure to tigecycline was more common in the case group than in the control group (9.8%, 6/61 vs. 2.2%, 2/91; p=0.046), this variable was found not to be a significant factor associated with tigecycline non-susceptibility after adjustment for other variables (adjusted OR 1.884, 95% CI 0.298-11.920; p=0.501). CONCLUSIONS These data suggest that tigecycline non-susceptible Acinetobacter spp have emerged and disseminated in the hospital in association with a recent exposure to carbapenems and an immunosuppressed state. This indicates that the rational use of antibiotics through a comprehensive antimicrobial stewardship program, especially in immunosuppressed patients, may be essential in limiting the emergence and spread of multidrug-resistant organisms such as tigecycline-resistant Acinetobacter spp, which are difficult to treat.
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Meropenem selection induced overproduction of the intrinsic carbapenemase as well as phenotype divergence in Acinetobacter baumannii. Int J Antimicrob Agents 2017; 50:419-426. [PMID: 28669829 DOI: 10.1016/j.ijantimicag.2017.04.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 03/31/2017] [Accepted: 04/05/2017] [Indexed: 01/24/2023]
Abstract
Acinetobacter baumannii 37662 is a carbapenem-susceptible isolate with blaOXA-51-like as the sole carbapenemase gene. Following selection with meropenem (MEM) at a subinhibitory concentration, two morphologically different mutants, designated 37662RM1 and 37662RM2, were obtained and characterised. Compared with the parent strain, resistant mutant 37662RM1 grew at a slower rate and had impaired capsule synthesis, whereas 37662RM2 grew fast and abolished capsule synthesis. In addition, the latter resistant mutant also lost pathogenicity but showed significantly enhanced biofilm formation. Transposition of the insertion sequence ISAba1 and formation of ISAba1-blaOXA-51-like was responsible for the upregulated expression of blaOXA-51-like. The blaOXA-51-like gene of A. baumannii 37662 is a close variant of blaOXA-138 and has been designated blaOXA-508. Overproduction of OXA-508 conferred major carbapenem resistance to these two mutants. Overall, these results indicate that a subinhibitory concentration of MEM can induce phenotype divergence together with carbapenem resistance in A. baumannii.
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Lin MF, Lin YY, Tu CC, Lan CY. Distribution of different efflux pump genes in clinical isolates of multidrug-resistant Acinetobacter baumannii and their correlation with antimicrobial resistance. JOURNAL OF MICROBIOLOGY, IMMUNOLOGY, AND INFECTION = WEI MIAN YU GAN RAN ZA ZHI 2017; 50:224-231. [DOI: 10.1016/j.jmii.2015.04.004] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 02/04/2015] [Accepted: 04/18/2015] [Indexed: 11/17/2022]
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Selasi GN, Nicholas A, Jeon H, Na SH, Kwon HI, Kim YJ, Heo ST, Oh MH, Lee JC. Differences in Biofilm Mass, Expression of Biofilm-Associated Genes, and Resistance to Desiccation between Epidemic and Sporadic Clones of Carbapenem-Resistant Acinetobacter baumannii Sequence Type 191. PLoS One 2016; 11:e0162576. [PMID: 27622249 PMCID: PMC5021322 DOI: 10.1371/journal.pone.0162576] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Accepted: 08/24/2016] [Indexed: 11/18/2022] Open
Abstract
Understanding the biology behind the epidemicity and persistence of Acinetobacter baumannii in the hospital environment is critical to control outbreaks of infection. This study investigated the contributing factors to the epidemicity of carbapenem-resistant A. baumannii (CRAB) sequence type (ST) 191 by comparing the differences in biofilm formation, expression of biofilm-associated genes, and resistance to desiccation between major epidemic (n = 16), minor epidemic (n = 12), and sporadic (n = 12) clones. Biofilm mass was significantly greater in the major epidemic than the minor epidemic and sporadic clones. Major and minor epidemic clones expressed biofilm-associated genes, abaI, bap, pgaABCD, and csuA/BABCDE, higher than the sporadic clones in sessile conditions. The csuC, csuD, and csuE genes were more highly expressed in the major epidemic than minor epidemic clones. Interestingly, minor epidemic clones expressed more biofilm-associated genes than the major epidemic clone under planktonic conditions. Major epidemic clones were more resistant to desiccation than minor epidemic and sporadic clones on day 21. In conclusion, the epidemic CRAB ST191 clones exhibit a higher capacity to form biofilms, express the biofilm-associated genes under sessile conditions, and resist desiccation than sporadic clones. These phenotypic and genotypic characteristics of CRAB ST191 may account for the epidemicity of specific CRAB ST191 clones in the hospital.
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Affiliation(s)
- Gati Noble Selasi
- Department of Microbiology, Kyungpook National University School of Medicine, Daegu, Republic of Korea
| | - Asiimwe Nicholas
- Department of Microbiology, Kyungpook National University School of Medicine, Daegu, Republic of Korea
| | - Hyejin Jeon
- Department of Microbiology, Kyungpook National University School of Medicine, Daegu, Republic of Korea
| | - Seok Hyeon Na
- Department of Microbiology, Kyungpook National University School of Medicine, Daegu, Republic of Korea
| | - Hyo Il Kwon
- Department of Microbiology, Kyungpook National University School of Medicine, Daegu, Republic of Korea
| | - Yoo Jeong Kim
- Department of Microbiology, Kyungpook National University School of Medicine, Daegu, Republic of Korea
| | - Sang Taek Heo
- Department of Internal Medicine, Jeju National University School of Medicine, Jeju, Republic of Korea
| | - Man Hwan Oh
- Department of Nanobiomedical Science, Dankook University, Cheonan, Republic of Korea
| | - Je Chul Lee
- Department of Microbiology, Kyungpook National University School of Medicine, Daegu, Republic of Korea
- * E-mail:
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El-Mahdy TS, Al-Agamy MH, Al-Qahtani AA, Shibl AM. Detection of bla OXA-23-like and bla NDM-1 in Acinetobacter baumannii from the Eastern Region, Saudi Arabia. Microb Drug Resist 2016; 23:115-121. [PMID: 27183378 DOI: 10.1089/mdr.2015.0304] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Acinetobacter baumannii is currently considered as one of the most common successful pathogens in the healthcare system due to its ability to quickly develop resistance. Ten carbapenem-resistant A. calcoaceticus-baumannii complex were isolated from the eastern region, Saudi Arabia in 2014. All isolates were resistant to ciprofloxacin, however, 8 of 10 isolates were tigecycline resistant. Susceptibility test was also carried out for three aminoglycosides, resistance to gentamicin was 80%, amikacin was 90%, and tobramycin was 50%. Colistin susceptibility was seen in all isolates. The 10 isolates harbored blaOXA-23-like and ISAba1 and 9 of them also carried blaADC. Three isolates of 10 harbored blaNDM-1 coding for NDM metallo-β-lactamase (MBL) with coexistence of blaADC together with either blaGES or blaTEM or both. Those three isolates exhibited negative Etest MBL screening test. Pulsed-field gel electrophoresis revealed the high clonal variability of the isolates, although two isolates were indistinguishable. The risk of dissemination of carbapenem resistance through presence of ISAba1 upstream of OXA-23-like in all isolates raises the concern about emergence of higher carbapenem prevalence rates in the future in our region. This study also demonstrated the importance of molecular surveillance to provide accurate and reliable data about the resistance rates of A. baumannii. Finally, the high incidence of NDM-1 among our isolates requires a routine surveillance to monitor the future prevalence of this enzyme in the region.
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Affiliation(s)
- Taghrid S El-Mahdy
- 1 Department of Biomedical Sciences, College of Clinical Pharmacy, King Faisal University , Hofuf, Al-Ahsa, Saudi Arabia .,2 Department of Microbiology and Immunology, Faculty of Pharmacy, Helwan University , Cairo, Egypt
| | - Mohamed H Al-Agamy
- 3 Department of Pharmaceutics and Microbiology, College of Pharmacy, King Saud University , Riyadh, Saudi Arabia .,4 Microbiology and Immunology Department, Faculty of Pharmacy, Al-Azhar University , Cairo, Egypt
| | - Ahmed A Al-Qahtani
- 5 Department of Infection and Immunity, King Faisal Specialist Hospital and Research Center , Riyadh, Saudi Arabia
| | - Atef M Shibl
- 3 Department of Pharmaceutics and Microbiology, College of Pharmacy, King Saud University , Riyadh, Saudi Arabia
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Pagdepanichkit S, Tribuddharat C, Chuanchuen R. Distribution and expression of the Ade multidrug efflux systems in Acinetobacter baumannii clinical isolates. Can J Microbiol 2016; 62:794-801. [PMID: 27332787 DOI: 10.1139/cjm-2015-0730] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
One hundred Acinetobacter baumannii clinical isolates were examined for inhibitory effect of reserpine and carbonyl cyanide m-chlorophenylhydrazone (CCCP) on the antimicrobial susceptibility and expression of 4 resistant-nodulation-cell division (RND)-type multidrug efflux systems, including AdeABC, AdeDE, AdeIJK, and AdeFGH, using RT-PCR. Ten A. baumannii isolates expressing AdeABC, AdeIJK, or AdeFGH were randomly selected for determination of transcription level and regulatory mutations. While all the isolates were resistant to multiple drugs, the reserpine and CCCP experiment showed that the multidrug resistance phenotype in most A. baumannii isolates was associated with efflux pumps. Most isolates expressed at least one of the RND-type efflux pumps tested (97%). AdeIJK expression was most common (97%), but none of the isolates produced AdeDE. Fifty-two percent of the A. baumannii isolates simultaneously produced up to 3 RND-type efflux systems (i.e., AdeABC, AdeFGH, and AdeIJK). No good correlation between the expression of RND-type efflux pumps and the type of antimicrobial resistance was observed. Overexpression of AdeABC, AdeIJK, and AdeFGH was not always related to the presence of mutations in their corresponding regulatory genes. This study highlights (i) the universal presence of the RND-type efflux pumps with variable levels of expression level among the A. baumannii in this collection and (ii) the complexity of their regulation of expression.
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Affiliation(s)
- Sirawit Pagdepanichkit
- a Research Unit in Microbial Food Safety and Antimicrobial Resistance, Department of Veterinary Public Health, Faculty of Veterinary Science, Chulalongkorn University, Bangkok 10330, Thailand
| | - Chanwit Tribuddharat
- b Department of Microbiology, Faculty of Medicine, Mahidol University, Bangkok, Thailand
| | - Rungtip Chuanchuen
- a Research Unit in Microbial Food Safety and Antimicrobial Resistance, Department of Veterinary Public Health, Faculty of Veterinary Science, Chulalongkorn University, Bangkok 10330, Thailand
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Modarresi F, Azizi O, Shakibaie MR, Motamedifar M, Mosadegh E, Mansouri S. Iron limitation enhances acyl homoserine lactone (AHL) production and biofilm formation in clinical isolates of Acinetobacter baumannii. Virulence 2016; 6:152-61. [PMID: 25622119 DOI: 10.1080/21505594.2014.1003001] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Acinetobacter baumannii is an important source of infections in intensive care units (ICUs) of our hospitals in Kerman, Iran and the most frequently isolated strains produce biofilm. There is a little information about role of iron (Fe) levels on acyl homoserine lactone (AHL) production and biofilm formation in this microorganism. In the present study, we investigated the influence of iron-III limitation on AHL, siderophore, catechol and virulence factors in the biofilm forming clinical strains of A. baumannii. A total of 65 non-duplicated multidrug resistance (MDR) strains of A. baumannii were isolated from patients in ICUs of 2 hospitals in Kerman, Iran. Antibiotic susceptibility, siderophore and other iron chelators, hemolysis, cell twitching motility, capsule, gelatinase and DNase were studied. Presence of quorum sensing, LuxI and LuxR genes was detected by multiplex-PCR. AHL activity quantified by colorimetric method and the functional groups were determined by Fourier Transform Infra-Red Spectroscopy (FT-IR). Biofilm formation was detected by microtiter plate technique. All of the isolates were resistant to third generation of cephalosporins, ciprofloxacin, levofloxacin, tetracycline, whereas, 78% and 81% were resistant to amikacin and carbapenems, respectively. The siderophore activity was highest at 20 μM Fe(3+) (70%); however, it decreased to 45% as concentration of Fe(3+) increased to 80 μM. Furthermore, screening of the isolates for LuxI and LuxR genes showed that presence of both genes required in the isolates with high AHL activity. FT-IR analysis indicated C=O bond of the lactone ring and primary amides. Significantly, a higher amount of AHL (70%) was detected in the presence of low concentration of iron-III (20 μM); as iron concentration increased to 80 μM, the AHL activity was reduced to 40% (P ≤ 0.05). All the isolates exhibited twitching motility and had a capsule. No any gelatinase or DNase activity was detected. Quantification of the biofilm formation introduced 23 isolates with efficient attachment to microplate wells and strong biofilm. We found that both the AHL production and biofilm formation were regulated by iron concentration in a dose dependent manner. These findings provide evidence that iron limitation plays an important regulatory role in AHL and siderophore production resulting in strong or weak biofilm, thereby helping the organism to persist in less available micronutrient environment.
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Affiliation(s)
- Farzan Modarresi
- a Department of Microbiology and Virology ; Kerman University of Medical Sciences ; Kerman , Iran
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Abstract
PURPOSE OF REVIEW An antimicrobial policy consisting of the initial use of wide-spectrum antimicrobials followed by a reassessment of treatment when culture results are available is termed de-escalation therapy. Our aim is to examine the safety and feasibility of antibiotic de-escalation in critically ill patients providing practical tips about how to accomplish this strategy in the critical care setting. RECENT FINDINGS Numerous studies have assessed the rates of de-escalation therapy (range from 10 to 60%) in patients with severe sepsis or ventilator-associated pneumonia as well as the factors associated with de-escalation. De-escalation generally refers to a reduction in the spectrum of administered antibiotics through the discontinuation of antibiotics or switching to an agent with a narrower spectrum. Diverse studies have identified the adequacy of initial therapy as a factor independently associated with de-escalation. Negative impact on different outcome measures has not been reported in the observational studies. Two randomized clinical trials have evaluated this strategy in patients with ventilator-associated pneumonia or severe sepsis. These trials alert us about the possibility that this strategy may be linked to a higher rate of reinfections but without an impact on mortality. SUMMARY Antibiotic de-escalation is a well tolerated management strategy in critically ill patients but unfortunately is not widely adopted.
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Lai JH, Yang JT, Chern J, Chen TL, Wu WL, Liao JH, Tsai SF, Liang SY, Chou CC, Wu SH. Comparative Phosphoproteomics Reveals the Role of AmpC β-lactamase Phosphorylation in the Clinical Imipenem-resistant Strain Acinetobacter baumannii SK17. Mol Cell Proteomics 2015; 15:12-25. [PMID: 26499836 DOI: 10.1074/mcp.m115.051052] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Indexed: 01/13/2023] Open
Abstract
Nosocomial infectious outbreaks caused by multidrug-resistant Acinetobacter baumannii have emerged as a serious threat to human health. Phosphoproteomics of pathogenic bacteria has been used to identify the mechanisms of bacterial virulence and antimicrobial resistance. In this study, we used a shotgun strategy combined with high-accuracy mass spectrometry to analyze the phosphoproteomics of the imipenem-susceptible strain SK17-S and -resistant strain SK17-R. We identified 410 phosphosites on 248 unique phosphoproteins in SK17-S and 285 phosphosites on 211 unique phosphoproteins in SK17-R. The distributions of the Ser/Thr/Tyr/Asp/His phosphosites in SK17-S and SK17-R were 47.0%/27.6%/12.4%/8.0%/4.9% versus 41.4%/29.5%/17.5%/6.7%/4.9%, respectively. The Ser-90 phosphosite, located on the catalytic motif S(88)VS(90)K of the AmpC β-lactamase, was first identified in SK17-S. Based on site-directed mutagenesis, the nonphosphorylatable mutant S90A was found to be more resistant to imipenem, whereas the phosphorylation-simulated mutant S90D was sensitive to imipenem. Additionally, the S90A mutant protein exhibited higher β-lactamase activity and conferred greater bacterial protection against imipenem in SK17-S compared with the wild-type. In sum, our results revealed that in A. baumannii, Ser-90 phosphorylation of AmpC negatively regulates both β-lactamase activity and the ability to counteract the antibiotic effects of imipenem. These findings highlight the impact of phosphorylation-mediated regulation in antibiotic-resistant bacteria on future drug design and new therapies.
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Affiliation(s)
- Juo-Hsin Lai
- From the ‡Institute of Biochemical Sciences, College of Life Sciences, National Taiwan University, Taipei 10617, Taiwan; §Institute of Biological Chemistry, Academia Sinica. Taipei 11529, Taiwan
| | - Jhih-Tian Yang
- §Institute of Biological Chemistry, Academia Sinica. Taipei 11529, Taiwan; ¶Ph.D. Program in Microbial Genomics, National Chung Hsing University and Academia Sinica, Taiwan
| | - Jeffy Chern
- §Institute of Biological Chemistry, Academia Sinica. Taipei 11529, Taiwan; ‖Chemical Biology and Molecular Biophysics Program, Taiwan International Graduate Program, Academia Sinica, Taipei 11529, Taiwan; **Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
| | - Te-Li Chen
- ‡‡Institute of Clinical Medicine, School of Medicine, National Yang Ming University, Taipei 11221, Taiwan; §§Division of Infectious Diseases, Department of Medicine, Taipei Veterans General Hospital, Taipei 11217, Taiwan; ¶¶Department of Medicine, Cheng Hsin General Hospital, Taipei 11220, Taiwan
| | - Wan-Ling Wu
- §Institute of Biological Chemistry, Academia Sinica. Taipei 11529, Taiwan
| | - Jiahn-Haur Liao
- §Institute of Biological Chemistry, Academia Sinica. Taipei 11529, Taiwan
| | - Shih-Feng Tsai
- ‖‖Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taipei 11221, Taiwan; Institute of Molecular and Genomic Medicine, National Health Research Institutes, Miaoli 35053, Taiwan
| | - Suh-Yuen Liang
- §Institute of Biological Chemistry, Academia Sinica. Taipei 11529, Taiwan; Core Facilities for Protein Structural Analysis, Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
| | - Chi-Chi Chou
- §Institute of Biological Chemistry, Academia Sinica. Taipei 11529, Taiwan; Core Facilities for Protein Structural Analysis, Institute of Biological Chemistry, Academia Sinica, Taipei 11529, Taiwan
| | - Shih-Hsiung Wu
- From the ‡Institute of Biochemical Sciences, College of Life Sciences, National Taiwan University, Taipei 10617, Taiwan; §Institute of Biological Chemistry, Academia Sinica. Taipei 11529, Taiwan; ‖Chemical Biology and Molecular Biophysics Program, Taiwan International Graduate Program, Academia Sinica, Taipei 11529, Taiwan; **Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan;
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Li P, Niu W, Li H, Lei H, Liu W, Zhao X, Guo L, Zou D, Yuan X, Liu H, Yuan J, Bai C. Rapid detection of Acinetobacter baumannii and molecular epidemiology of carbapenem-resistant A. baumannii in two comprehensive hospitals of Beijing, China. Front Microbiol 2015; 6:997. [PMID: 26441924 PMCID: PMC4585070 DOI: 10.3389/fmicb.2015.00997] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 09/07/2015] [Indexed: 12/21/2022] Open
Abstract
Acinetobacter baumannii is an important opportunistic pathogen associated with a variety of nosocomial infections. A rapid and sensitive molecular detection in clinical isolates is quite needed for the appropriate therapy and outbreak control of A. baumannii. Group 2 carbapenems have been considered the agents of choice for the treatment of multiple drug-resistant A. baumannii. But the prevalence of carbapenem-resistant A. baumannii (CRAB) has been steadily increasing in recent years. Here, we developed a loop-mediated isothermal amplification (LAMP) assay for the rapid detection of A. baumannii in clinical samples by using high-specificity primers of the bla OXA-51 gene. Then we investigated the OXA-carbapenemases molecular epidemiology of A. baumannii isolates in two comprehensive hospitals in Beijing. The results showed that the LAMP assay could detect target DNA within 60 min at 65°C. The detection limit was 50 pg/μl, which was about 10-fold greater than that of PCR. Furthermore, this method could distinguish A. baumannii from the homologous A. nosocomialis and A. pittii. A total of 228 positive isolates were identified by this LAMP-based method for A. baumannii from 335 intensive care unit patients with clinically suspected multi-resistant infections in two hospitals in Beijing. The rates of CRAB are on the rise and are slowly becoming a routine phenotype for A. baumannii. Among the CRABs, 92.3% harbored both the bla OXA-23 and bla OXA-51 genes. Thirty-three pulsotypes were identified by pulsed-field gel electrophoresis, and the majority belonged to clone C. In conclusion, the LAMP method developed for detecting A. baumannii was faster and simpler than conventional PCR and has great potential for both point-of-care testing and basic research. We further demonstrated a high distribution of class D carbapenemase-encoding genes, mainly OXA-23, which presents an emerging threat in hospitals in China.
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Affiliation(s)
- Puyuan Li
- Department of Respiratory and Critical Care Diseases, 307th Hospital of Chinese People's Liberation Army Beijing, China
| | - Wenkai Niu
- Department of Respiratory and Critical Care Diseases, 307th Hospital of Chinese People's Liberation Army Beijing, China
| | - Huan Li
- Institute of Disease Control and Prevention, Academy of Military Medical Sciences Beijing, China
| | - Hong Lei
- Department of Clinical Laboratory, 309th Hospital of Chinese People's Liberation Army Beijing, China
| | - Wei Liu
- Institute of Disease Control and Prevention, Academy of Military Medical Sciences Beijing, China
| | - Xiangna Zhao
- Institute of Disease Control and Prevention, Academy of Military Medical Sciences Beijing, China
| | - Leijing Guo
- Department of Respiratory and Critical Care Diseases, 307th Hospital of Chinese People's Liberation Army Beijing, China
| | - Dayang Zou
- Institute of Disease Control and Prevention, Academy of Military Medical Sciences Beijing, China
| | - Xin Yuan
- Department of Respiratory and Critical Care Diseases, 307th Hospital of Chinese People's Liberation Army Beijing, China
| | - Huiying Liu
- Department of Respiratory and Critical Care Diseases, 307th Hospital of Chinese People's Liberation Army Beijing, China
| | - Jing Yuan
- Institute of Disease Control and Prevention, Academy of Military Medical Sciences Beijing, China
| | - Changqing Bai
- Department of Respiratory and Critical Care Diseases, 307th Hospital of Chinese People's Liberation Army Beijing, China
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Fonseca EL, Marin MA, Encinas F, Vicente ACP. Full characterization of the integrative and conjugative element carrying the metallo-β-lactamaseblaSPM-1and bicyclomycinbcr1resistance genes found in the pandemicPseudomonas aeruginosaclone SP/ST277 : Figure 1. J Antimicrob Chemother 2015; 70:2547-50. [DOI: 10.1093/jac/dkv152] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 05/14/2015] [Indexed: 11/14/2022] Open
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Azizi O, Shakibaie MR, Modarresi F, Shahcheraghi F. Molecular Detection of Class-D OXA Carbapenemase Genes in Biofilm and Non-Biofilm Forming Clinical Isolates of Acinetobacter baumannii. Jundishapur J Microbiol 2015; 8:e21042. [PMID: 25789134 PMCID: PMC4350054 DOI: 10.5812/jjm.21042] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Revised: 11/10/2014] [Accepted: 11/20/2014] [Indexed: 02/05/2023] Open
Abstract
Background: Emergence and spread of carbapenemase (blaOXA) genes in multidrug resistant Acinetobacter baumannii (MDR-AB) forming biofilm complicated treatment of the patients infected with this microorganism particularly in intensive care units (ICUs). Objectives: The current study aimed to determine the prevalence of molecular class-D OXA carbapenemase in biofilm and non-biofilm forming strains of MDR-AB. Materials and Methods: A total of 65 strains of MDR-AB were isolated from the patients hospitalized in the ICU of two hospitals in Kerman, Iran. The isolates were identified by conventional microbiological tests as well as API 20NE assay. Antibiotic susceptibility was carried out by disk diffusion method; minimum inhibitory concentration (MIC) of carbapenems was measured by E-test. The presence of blaOXA genes among the isolates were studied by duplex-polymerase chain reaction and application of appropriate primers. Biofilm formation was detected by microtiter plate method. Results: The isolates were highly resistant to ciprofloxacin, levofloxacin, piperacillin, nalidixic acid and third generation cephalosporins such as tigecycline (7%; n = 5) and colistin (13%; n = 8). Among the isolates, 77% (n = 50) exhibited high MIC (265μg/mL) for imipenem. Both the blaOXA-51 and blaOXA-23 like genes coexisted in all the isolates; while, blaOXA-24/40 like gene was only detected in 29 imipenem-resistant strains (P ≤ 0.05). The blaOXA-58 like gene was not detected among the isolated strains. Quantification of biofilm introduced 23 isolates (including blaOXA-24/40 strains) with efficient attachment to microtiter plate; while, those isolates without blaOXA-24/40, or imipenem-sensitive strains formed weak or no biofilm. Conclusions: Coexistence of the blaOXA-51, blaOXA-23 and blaOXA-24/40 like genes, along with formation of strong biofilm, in MDR-AB strains particularly with indiscriminate use of imipenem, complicated treatment of the patients infected with these bacteria in the hospitals understudy.
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Affiliation(s)
- Omid Azizi
- Department of Microbiology and Virology, Kerman University of Medical Sciences, Kerman, IR Iran
| | - Mohammad Reza Shakibaie
- Department of Microbiology and Virology, Kerman University of Medical Sciences, Kerman, IR Iran
- Research Center for Infectious Diseases and Tropical Medicine, Kerman University of Medical Sciences, Kerman, IR Iran
- Corresponding author: Mohammad Reza Shakibaie, Department of Microbiology and Virology, Kerman University of Medical Sciences, Kerman, IR Iran. Tel: +98-9133408226, Fax: +98-3413221671, E-mail:
| | - Farzan Modarresi
- Department of Microbiology and Virology, Kerman University of Medical Sciences, Kerman, IR Iran
| | - Fereshteh Shahcheraghi
- Microbiology Research Center, Department of Bacteriology, Pasteur Institute of Iran, Tehran, IR Iran
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Lin MF, Lan CY. Antimicrobial resistance in Acinetobacter baumannii: From bench to bedside. World J Clin Cases 2014; 2:787-814. [PMID: 25516853 PMCID: PMC4266826 DOI: 10.12998/wjcc.v2.i12.787] [Citation(s) in RCA: 203] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/26/2014] [Revised: 08/25/2014] [Accepted: 10/27/2014] [Indexed: 02/05/2023] Open
Abstract
Acinetobacter baumannii (A. baumannii) is undoubtedly one of the most successful pathogens in the modern healthcare system. With invasive procedures, antibiotic use and immunocompromised hosts increasing in recent years, A. baumannii has become endemic in hospitals due to its versatile genetic machinery, which allows it to quickly evolve resistance factors, and to its remarkable ability to tolerate harsh environments. Infections and outbreaks caused by multidrug-resistant A. baumannii (MDRAB) are prevalent and have been reported worldwide over the past twenty or more years. To address this problem effectively, knowledge of species identification, typing methods, clinical manifestations, risk factors, and virulence factors is essential. The global epidemiology of MDRAB is monitored by persistent surveillance programs. Because few effective antibiotics are available, clinicians often face serious challenges when treating patients with MDRAB. Therefore, a deep understanding of the resistance mechanisms used by MDRAB can shed light on two possible strategies to combat the dissemination of antimicrobial resistance: stringent infection control and antibiotic treatments, of which colistin-based combination therapy is the mainstream strategy. However, due to the current unsatisfying therapeutic outcomes, there is a great need to develop and evaluate the efficacy of new antibiotics and to understand the role of other potential alternatives, such as antimicrobial peptides, in the treatment of MDRAB infections.
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First emergence of acrAB and oqxAB mediated tigecycline resistance in clinical isolates of Klebsiella pneumoniae pre-dating the use of tigecycline in a Chinese hospital. PLoS One 2014; 9:e115185. [PMID: 25503276 PMCID: PMC4264890 DOI: 10.1371/journal.pone.0115185] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Accepted: 11/19/2014] [Indexed: 01/05/2023] Open
Abstract
Tigecycline is one of the few therapeutic options for treating infections caused by some multi-drug resistant pathogens, such as Klebsiella pneumoniae. However, tigecycline-resistant K. pneumoniae has been discovered recently in China. From 2009 to 2013, nine tigecycline-resistant K. pneumoniae isolates were identified in our hospital. Six of nine strains were identified before using tigecycline. To investigate the efflux-mediated resistance mechanisms of K. pneumoniae, the expression of efflux pump genes (acrA, acrB, tolC, oqxA and oqxB) and pump regulators (acrR, marA, soxS, rarA, rob and ramA) were examined by real-time RT-PCR. Molecular typing of the tigecycline resistant strains was performed. ST11 was the predominant clone of K. pneumoniae strains, while ST1414 and ST1415 were novel STs. Efflux pump inhibitor (EPI)-carbonyl cyanide chlorophenylhydrazone (CCCP) was able to reverse the resistance patterns of 5 resistant K. pneumoniae strains. In comparison with strain A111, a tigecycline-susceptible strain (negative control), we found that the expression levels of efflux pump genes and pump regulators were higher in a majority of resistant strains. Higher expression levels of regulators rarA (2.41-fold, 9.55-fold, 28.44-fold and 18.31-fold, respectively) and pump gene oqxB (3.87-fold, 31.96-fold, 50.61-fold and 29.45-fold, respectively) were observed in four tigecycline resistant strains (A363, A361, A368, A373, respectively). Increased expression of acrB was associated with ramA and marA expression. To our knowledge, studies on tigecycline resistance mechanism in K. pneumoniae are limited especially in China. In our study, we found that both efflux pump AcrAB-TolC and OqxAB contributed to tigecycline resistance in K. pneumoniae isolates.
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Elabd FM, Al-Ayed MSZ, Asaad AM, Alsareii SA, Qureshi MA, Musa HAA. Molecular characterization of oxacillinases among carbapenem-resistant Acinetobacter baumannii nosocomial isolates in a Saudi hospital. J Infect Public Health 2014; 8:242-7. [PMID: 25466594 DOI: 10.1016/j.jiph.2014.10.002] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 09/30/2014] [Accepted: 10/02/2014] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Acinetobacter baumannii has successfully become a significant nosocomial pathogen because of its remarkable ability to acquire antibiotic resistance and to survive in nosocomial environments. This study aimed to determine the drug susceptibility patterns and the distribution of four subgroups of carbapenem-hydrolyzing class D β-lactamases (OXA-carbapenemases), as well as their insertion sequences (ISAba1), among A. baumannii nosocomial isolates from a Saudi tertiary care hospital. METHODS A total of 108 non-duplicate A. baumannii isolates were identified, and their susceptibilities to different antibiotics were determined using the breakpoint method. Isolates were then subjected to multiplex-PCR targeting blaOXA genes. RESULTS More than 75% of the isolates showed resistance to different antibiotics. The rates of susceptibility to colistin, meropenem, imipenem and trimethoprim-sulfamethoxazole were 95.6, 50, 48.1 and 34.3%, respectively. All isolates possessed a blaOXA-51-like gene. Of the 56 carbapenem-resistant isolates, 48 isolates (85.7%) carried blaOXA-23-like, 3 isolates (5.4%) carried blaOXA-40-like and two isolates (3.6%) had blaOXA-58-like genes. The ISAba1 element was found upstream of the blaOXA-23 and blaOXA-24 genes in 40 (71.4%) and 3 (5.4%) isolates, respectively, while it was detected upstream of blaOXA-51 in only one (1.8%) isolate. CONCLUSION Our findings further illustrate the challenge of increasing carbapenem-resistance in A. baumannii isolates in Saudi Arabia. The high distribution of class D carbapenemase-encoding genes, mainly ISAba1/OXA-23 and ISAba1/OXA-24 carbapenemases, is worrisome and presents an emerging threat in our hospital. Local molecular surveillance is essential to help control carbapenem-resistant A. baumannii nosocomial infections and to prevent DNA exchange among endemic nosocomial pathogens.
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Affiliation(s)
| | | | - Ahmed M Asaad
- College of Medicine, Najran University, Najran, Saudi Arabia.
| | - Saeed A Alsareii
- College of Dentistry, Vice Dean of College of Medicine, Najran University, Saudi Arabia.
| | - Mohamed A Qureshi
- College of Applied Medical Sciences, Najran University, Najran, Saudi Arabia.
| | - Hassan A-A Musa
- College of Medicine, National Ribat University, Khartoum, Sudan.
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Chang KC, Kuo HY, Tang CY, Chang CW, Lu CW, Liu CC, Lin HR, Chen KH, Liou ML. Transcriptome profiling in imipenem-selected Acinetobacter baumannii. BMC Genomics 2014; 15:815. [PMID: 25260865 PMCID: PMC4192346 DOI: 10.1186/1471-2164-15-815] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2014] [Accepted: 09/18/2014] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND Carbapenem-resistance in Acinetobacter baumannii has gradually become a global challenge. To identify the genes involved in carbapenem resistance in A. baumannii, the transcriptomic responses of the completely sequenced strain ATCC 17978 selected with 0.5 mg/L (IPM-2 m) and 2 mg/L (IPM-8 m) imipenem were investigated using RNA-sequencing to identify differences in the gene expression patterns. RESULTS A total of 88 and 68 genes were differentially expressed in response to IPM-2 m and IPM-8 m selection, respectively. Among the expressed genes, 50 genes were highly expressed in IPM-2 m, 30 genes were highly expressed in IPM-8 m, and 38 genes were expressed common in both strains. Six groups of genes were simultaneously expressed in IPM-2 m and IPM-8 m mutants. The three gene groups involved in DNA recombination were up-regulated, including recombinase, transposase and DNA repair, and beta-lactamase OXA-95 and homologous recombination. The remaining gene groups involved in biofilm formation were down-regulated, including quorum sensing, secretion systems, and the csu operon. The antibiotic resistance determinants, including RND efflux transporters and multidrug resistance pumps, were over-expressed in response to IPM-2 m selection, followed by a decrease in response to IPM-8 m selection. Among the genes over-expressed in both strains, blaOXA-95, previously clustered with the blaOXA-51-like family, showed 14-fold (IPM-2 m) to 330-fold (IPM-8 m) over-expression. The expression of blaOXA-95 in IPM-2 m and IPM-8 m cells was positively correlated with the rate of imipenem hydrolysis, as demonstrated through Liquid Chromatography-Mass Spectrometry/Mass Spectrometry, suggesting that blaOXA-95 plays a critical role in conferring carbapenem resistance. In addition, A. baumannii shows an inverse relationship between carbapenem resistance and biofilm production. CONCLUSION Gene recombination and blaOXA-95 play critical roles in carbapenem resistance in A. baumannii. Taken together, the results of the present study provide a foundation for future studies of the network systems associated with carbapenem resistance.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Ming-Li Liou
- Department of Computer Science and Information Engineering, Providence University, Taichung, Taichung County, Taiwan.
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AdeRS combination codes differentiate the response to efflux pump inhibitors in tigecycline-resistant isolates of extensively drug-resistant Acinetobacter baumannii. Eur J Clin Microbiol Infect Dis 2014; 33:2141-7. [DOI: 10.1007/s10096-014-2179-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Accepted: 06/01/2014] [Indexed: 01/25/2023]
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Yoon YK, Yang KS, Lee SE, Kim HJ, Sohn JW, Kim MJ. Effects of Group 1 versus Group 2 carbapenems on the susceptibility of Acinetobacter baumannii to carbapenems: a before and after intervention study of carbapenem-use stewardship. PLoS One 2014; 9:e99101. [PMID: 24911244 PMCID: PMC4049602 DOI: 10.1371/journal.pone.0099101] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Accepted: 05/11/2014] [Indexed: 12/04/2022] Open
Abstract
Objective Antimicrobial stewardship programs have been proposed for reducing bacterial resistance in the hospital environment. The purpose of this study was to investigate the impact of a carbapenem-use stewardship program on the susceptibility of Acinetobacter baumannii to Group 2 carbapenems. Methods A before and after intervention study was conducted at a university hospital from September 2008 to February 2013. Three study periods were defined: Phase I, pre-intervention (months 1–18); Phase II, a postintervention period during which ertapenem use was mandated but carbapenem use was not restricted (months 19–36); and Phase III, a postintervention period during which Group 2 carbapenem use was restricted (months 37–54). Results During the study period, intervention resulted in diminished consumption of Group 2 carbapenems (antimicrobial use density (AUD): 21.3±6.0 in Phase I, 18.8±6.0 in Phase II, 16.1±4.4 in Phase III; P = 0.028) and increased consumption of ertapenem (AUD: 2.7±1.7 in Phase I, 7.2±4.5 in Phase II, 9.1±5.3 in Phase III; P<0.001). The use of autoregressive-error models showed that in contrast with ertapenem use, the use of Group 2 carbapenem during the previous one month was positively and significantly associated with a subsequent increase in the proportion of carbapenem-resistant A. baumannii (CRAB) (P = 0.031). Conclusions Implementing a carbapenem-use stewardship program featuring the preferential use of ertapenem for treating appropriate indications of infection resulted in reduced use of Group 2 carbapenems and had a positive impact on the susceptibility of A. baumannii to carbapenems. This approach could be integrated into CRAB-control strategies in hospitals.
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Affiliation(s)
- Young Kyung Yoon
- Division of Infectious Diseases, Department of Internal Medicine, Korea University College of Medicine, Seoul, Republic of Korea
- Institute of Emerging Infectious Diseases, Korea University College of Medicine, Seoul, Republic of Korea
- Infection Control Unit, Korea University Anam Hospital, Seoul, Republic of Korea
| | - Kyung Sook Yang
- Department of Biostatistics, Korea University College of Medicine, Seoul, Republic of Korea
| | - Seung Eun Lee
- Infection Control Unit, Korea University Anam Hospital, Seoul, Republic of Korea
| | - Hyun Jeong Kim
- Infection Control Unit, Korea University Anam Hospital, Seoul, Republic of Korea
| | - Jang Wook Sohn
- Division of Infectious Diseases, Department of Internal Medicine, Korea University College of Medicine, Seoul, Republic of Korea
- Institute of Emerging Infectious Diseases, Korea University College of Medicine, Seoul, Republic of Korea
- Infection Control Unit, Korea University Anam Hospital, Seoul, Republic of Korea
| | - Min Ja Kim
- Division of Infectious Diseases, Department of Internal Medicine, Korea University College of Medicine, Seoul, Republic of Korea
- Institute of Emerging Infectious Diseases, Korea University College of Medicine, Seoul, Republic of Korea
- Infection Control Unit, Korea University Anam Hospital, Seoul, Republic of Korea
- * E-mail:
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Kuo HY, Chang KC, Liu CC, Tang CY, Peng JH, Lu CW, Tu CC, Liou ML. Insertion sequence transposition determines imipenem resistance in Acinetobacter baumannii. Microb Drug Resist 2014; 20:410-5. [PMID: 24833435 DOI: 10.1089/mdr.2014.0004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
This study employed genomewide analysis to investigate potential resistance mechanisms in Acinetobacter baumannii following imipenem exposure. Imipenem-selected mutants were generated from the imipenem-susceptible strain ATCC 17978 by multistep selection resistance. Antibiotic susceptibilities were examined, and the selected mutants originated from the ATCC 17978 strain were confirmed by pulsed-field gel electrophoresis. The genomic sequence of a resistant mutant was analyzed using a next-generation sequencing platform, and genetic recombination was further confirmed by PCR. The result showed that phenotypic resistance was observed with carbapenem upon exposure to various concentrations of imipenem. Genomewide analysis showed that ISAba1 transposition was initiated by imipenem exposure at concentrations up to 0.5 mg/L. Transposition of ISAba1 upstream of blaOXA-95 was detected in all the selected mutants. The expression of blaOXA-95 was further analyzed by quantitative PCR, and the results demonstrated that a 200-fold increase in gene expression was required for resistance to imipenem. This study concluded that imipenem exposure at a concentration of 0.5 mg/L mediated the transposition of ISAba1 upstream of the blaOXA-95 gene and resulted in the overexpression of blaOXA-95 gene, which may play a major role in the resistance to imipenem in A. baumannii.
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Affiliation(s)
- Han-Yueh Kuo
- 1 Department of Medicine, National Taiwan University Hospital Hsin-Chu Branch , Hsin-Chu City, Taiwan
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Fonseca EL, Scheidegger E, Freitas FS, Cipriano R, Vicente ACP. Carbapenem-resistant Acinetobacter baumannii from Brazil: role of carO alleles expression and blaOXA-23 gene. BMC Microbiol 2013; 13:245. [PMID: 24195496 PMCID: PMC4228306 DOI: 10.1186/1471-2180-13-245] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Accepted: 10/18/2013] [Indexed: 02/06/2023] Open
Abstract
Background Carbapenems are the antibiotics of choice to treat infections caused by Acinetobacter baumannii, and resistance to this class can be determined by loss of membrane permeability and enzymatic mechanisms. Here, we analyzed the basis of carbapenem resistance in clinical A. baumannii isolates from different Brazilian regions. Results The analyses addressed the carbapenemase activity of OXA-23, CarO expression and alterations in its primary structure. Susceptibility test revealed that the strains presented the COS (Colistin-Only-Sensitive) profile. PCR and sequencing showed the presence of the chromosomally-encoded blaOXA-51 in all isolates. The majority of strains (53%) carried the carbapenemase blaOXA-23 gene associated with ISAba1. The Hodge test indicated that these strains are carbapenemase producers. PFGE revealed 14 genotypes among strains from Rio de Janeiro and Maranhão. The influence of carO on imipenem resistance was evaluated considering two aspects: the composition of the primary amino acid sequence; and the expression level of this porin. Sequencing and in silico analyses showed the occurrence of CarOa, CarOb and undefined CarO types, and Real Time RT-PCR revealed basal and reduced carO transcription levels among isolates. Conclusions We concluded that, in general, for these Brazilian isolates, the major carbapenem resistance mechanism was due to OXA-23 carbapenemase activity and that loss of CarO porin plays a minor role in this phenotype. However, it was possible to associate the carO alleles and their expression with imipenem resistance. Therefore, these findings underline the complexity in addressing the role of different mechanisms in carbapenem resistance and highlight the possible influence of CarO type in this phenotype.
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Affiliation(s)
- Erica Lourenço Fonseca
- Laboratório de Genética Molecular de Microrganismos, Instituto Oswaldo Cruz, FIOCRUZ, Rio de Janeiro, Brazil.
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Molecular epidemiology and mechanisms of tigecycline resistance in clinical isolates of Acinetobacter baumannii from a Chinese university hospital. Antimicrob Agents Chemother 2013; 58:297-303. [PMID: 24165187 DOI: 10.1128/aac.01727-13] [Citation(s) in RCA: 130] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Because of its remarkable ability to acquire antibiotic resistance and to survive in nosocomial environments, Acinetobacter baumannii has become a significant nosocomial infectious agent worldwide. Tigecycline is one of the few therapeutic options for treating infections caused by A. baumannii isolates. However, tigecycline resistance has increasingly been reported. Our aim was to assess the prevalence and characteristics of efflux-based tigecycline resistance in clinical isolates of A. baumannii collected from a hospital in China. A total of 74 A. baumannii isolates, including 64 tigecycline-nonsusceptible A. baumannii (TNAB) and 10 tigecycline-susceptible A. baumannii (TSAB) isolates, were analyzed. The majority of them were determined to be positive for adeABC, adeRS, adeIJK, and abeM, while the adeE gene was found in only one TSAB isolate. Compared with the levels in TSAB isolates, the mean expression levels of adeB, adeJ, adeG, and abeM in TNAB isolates were observed to increase 29-, 3-, 0.7-, and 1-fold, respectively. The efflux pump inhibitors (EPIs) phenyl-arginine-β-naphthylamide (PAβN) and carbonyl cyanide 3-chlorophenylhydrazone (CCCP) could partially reverse the resistance pattern of tigecycline. Moreover, the tetX1 gene was detected in 12 (18.8%) TNAB isolates. To our knowledge, this is the first report of the tetX1 gene being detected in A. baumannii isolates. ST208 and ST191, which both clustered into clonal complex 92 (CC92), were the predominant sequence types (STs). This study showed that the active efflux pump AdeABC appeared to play important roles in the tigecycline resistance of A. baumannii. The dissemination of TNAB isolates in our hospital is attributable mainly to the spread of CC92.
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Huang Y, Wiradharma N, Xu K, Ji Z, Bi S, Li L, Yang YY, Fan W. Cationic amphiphilic alpha-helical peptides for the treatment of carbapenem-resistant Acinetobacter baumannii infection. Biomaterials 2012; 33:8841-7. [PMID: 22925814 DOI: 10.1016/j.biomaterials.2012.08.026] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2012] [Accepted: 08/12/2012] [Indexed: 12/30/2022]
Abstract
The emergence of multidrug-resistant Gram-negative bacteria, in particular Acinetobacter baumannii and Pseudomonas aeruginosa, is a critical clinical problem worldwide. Antimicrobial peptides (AMPs) have received increasing attention due to their ability to overcome multidrug-resistant microbes. We recently reported that cysteine-functionalized alpha-helical peptides LLKKLLKKC and CLLKKLLKKC effectively eradicated Gram-negative bacteria in vitro. In this study, the antibacterial properties of these peptides against carbapenem-resistant clinical isolates of A. baumannii were studied both in vitro and in vivo. The minimum inhibitory concentrations (MICs) of the peptides against 20 clinical isolates of carbapenem-resistant A. baumannii were determined in comparison with imipenem. The results showed that the A. baumannii isolates were more susceptible to (LLKK)(2)C than to C(LLKK)(2)C in vitro, and 90% of the 20 tested strains had an MIC of lower than or equal to 36.8 and 63.1 μmol/L, respectively. However, the bactericidal effect of C(LLKK)(2)C was much faster than that of (LLKK)(2)C. Furthermore, these peptides also showed excellent potency in mouse models of peritonitis and pneumonia infections caused by carbapenem-resistant A. baumannii. Importantly, both peptides had a high therapeutic index (>25), but caused no significant adverse effects on the liver and kidney functions and the balance of electrolytes in the blood. These peptides can be a promising alternative treatment modality to traditional antibiotics for nosocomial bacterial infections caused by multidrug-resistant Gram-negative bacteria, especially carbapenem-resistant A. baumannii.
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Affiliation(s)
- Yuan Huang
- Program of Innovative Therapeutics, The First Affiliated Hospital, Zhejiang University College of Medicine, Hangzhou 310003, China
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