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Campana EH, Kraychete GB, Montezzi LF, Xavier DE, Picão RC. Corrigendum to 'Description of a new non-Tn4401 element (NTE KPC-IIe) harboured on IncQ plasmid in Citrobacter werkmanii from recreational coastal water' [Journal of Global Antimicrobial Resistance 29 (2022) 207-211]. J Glob Antimicrob Resist 2023; 34:271. [PMID: 37689435 DOI: 10.1016/j.jgar.2023.07.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/11/2023] Open
Affiliation(s)
- Eloiza H Campana
- Laboratório de Investigação em Microbiologia Médica, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil; Laboratório de Microbiologia Clínica, Departamento de Ciências Farmacêuticas, Centro de Ciências da Saúde, Universidade Federal da Paraíba, João Pessoa, Brazil.
| | - Gabriela B Kraychete
- Laboratório de Investigação em Microbiologia Médica, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Lara F Montezzi
- Laboratório de Investigação em Microbiologia Médica, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Danilo E Xavier
- Departamento de Microbiologia - Instituto Aggeu Magalhães, FIOCRUZ, Pernambuco, Brazil
| | - Renata C Picão
- Laboratório de Investigação em Microbiologia Médica, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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Campana EH, Kraychete GB, Montezzi LF, Xavier DE, Picão RC. Description of a new non-Tn4401 element (NTE KPC-IIe) harboured on IncQ plasmid in Citrobacter werkmanii from recreational coastal water. J Glob Antimicrob Resist 2022; 29:207-211. [PMID: 35304865 DOI: 10.1016/j.jgar.2022.03.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 03/04/2022] [Accepted: 03/08/2022] [Indexed: 11/16/2022] Open
Abstract
OBJECTIVES Here we describe an IncQ1-like plasmid carrying blaKPC-2 in a new non-Tn4401 element found in Citrobacter werkmanii recovered from coastal water. METHODS In vitro and in silico approaches were used to assess antimicrobial resistance determinants, as well as blaKPC-2 vicinities. RESULTS The LB-887 isolate showed a multidrug-resistant phenotype and was identified as C. werkmanii. Resistome analysis identified further acquired resistance determinants to β-lactams, aminoglycosides, sulphonamides/trimethoprim, tetracyclines, chloramphenicol, macrolides, rifampicin and fluoroquinolones. Plasmidome included incompatibility groups IncA, IncC2, IncR, Col and IncQ families. The blaKPC-2 was inserted on a new variant of NTEKPC-II, called here NTEKPC-IIe, carried by an InQ1-like plasmid of 7930 kb (pKPC-LB887). NTEKPC-IIe differed from NTEKPC-IId by the complete absence of ISKpn6-tnpA. The InQ1-like backbone harbouring this element had been described in Enterobacterales recovered from clinical and environmental settings. CONCLUSION Unravelling genetic structures related to blaKPC dissemination in different settings may provide clues on the main forces driving evolution of this important resistance determinant. Indeed, the occurrence of blaKPC in a new NTEKPC variant from an environmental source highlights the ongoing evolution of this mobile genetic element. In addition, blaKPC carriage on a small and highly mobilizable IncQ plasmid in C. freundii complex from recreational water, similar to others found in clinical isolates, may suggest its relevance for blaKPC-2 dissemination among different compartments.
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Affiliation(s)
- Eloiza H Campana
- Laboratório de Investigação em Microbiologia Médica, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil; Laboratório de Microbiologia Clínica, Departamento de Ciências Farmacêuticas, Centro de Ciências da Saúde, Universidade Federal da Paraíba, João Pessoa, Brazil.
| | - Gabriela B Kraychete
- Laboratório de Investigação em Microbiologia Médica, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Lara F Montezzi
- Laboratório de Investigação em Microbiologia Médica, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Danilo E Xavier
- Departamento de Microbiologia - Instituto Aggeu Magalhães, FIOCRUZ, Pernambuco, Brazil
| | - Renata C Picão
- Laboratório de Investigação em Microbiologia Médica, Instituto de Microbiologia Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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Leal NC, Campos TL, Rezende AM, Docena C, Mendes-Marques CL, de Sá Cavalcanti FL, Wallau GL, Rocha IV, Cavalcanti CLB, Veras DL, Alves LR, Andrade-Figueiredo M, de Barros MPS, de Almeida AMP, de Morais MMC, Leal-Balbino TC, Xavier DE, de-Melo-Neto OP. Comparative Genomics of Acinetobacter baumannii Clinical Strains From Brazil Reveals Polyclonal Dissemination and Selective Exchange of Mobile Genetic Elements Associated With Resistance Genes. Front Microbiol 2020; 11:1176. [PMID: 32655514 PMCID: PMC7326025 DOI: 10.3389/fmicb.2020.01176] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2020] [Accepted: 05/08/2020] [Indexed: 12/13/2022] Open
Abstract
Acinetobacter baumannii is an opportunistic bacterial pathogen infecting immunocompromised patients and has gained attention worldwide due to its increased antimicrobial resistance. Here, we report a comparative whole-genome sequencing and analysis coupled with an assessment of antibiotic resistance of 46 Acinetobacter strains (45 A. baumannii plus one Acinetobacter nosocomialis) originated from five hospitals from the city of Recife, Brazil, between 2010 and 2014. An average of 3,809 genes were identified per genome, although only 2,006 genes were single copy orthologs or core genes conserved across all sequenced strains, with an average of 42 new genes found per strain. We evaluated genetic distance through a phylogenetic analysis and MLST as well as the presence of antibiotic resistance genes, virulence markers and mobile genetic elements (MGE). The phylogenetic analysis recovered distinct monophyletic A. baumannii groups corresponding to five known (ST1, ST15, ST25, ST79, and ST113) and one novel ST (ST881, related to ST1). A large number of ST specific genes were found, with the ST79 strains having the largest number of genes in common that were missing from the other STs. Multiple genes associated with resistance to β-lactams, aminoglycosides and other antibiotics were found. Some of those were clearly mapped to defined MGEs and an analysis of those revealed known elements as well as a novel Tn7-Tn3 transposon with a clear ST specific distribution. An association of selected resistance/virulence markers with specific STs was indeed observed, as well as the recent spread of the OXA-253 carbapenemase encoding gene. Virulence genes associated with the synthesis of the capsular antigens were noticeably more variable in the ST113 and ST79 strains. Indeed, several resistance and virulence genes were common to the ST79 and ST113 strains only, despite a greater genetic distance between them, suggesting common means of genetic exchange. Our comparative analysis reveals the spread of multiple STs and the genomic plasticity of A. baumannii from different hospitals in a single metropolitan area. It also highlights differences in the spread of resistance markers and other MGEs between the investigated STs, impacting on the monitoring and treatment of Acinetobacter in the ongoing and future outbreaks.
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Affiliation(s)
- Nilma C Leal
- Aggeu Magalhães Institute (IAM), Fundação Oswaldo Cruz (Fiocruz), Recife, Brazil
| | - Túlio L Campos
- Aggeu Magalhães Institute (IAM), Fundação Oswaldo Cruz (Fiocruz), Recife, Brazil
| | - Antonio M Rezende
- Aggeu Magalhães Institute (IAM), Fundação Oswaldo Cruz (Fiocruz), Recife, Brazil
| | - Cássia Docena
- Aggeu Magalhães Institute (IAM), Fundação Oswaldo Cruz (Fiocruz), Recife, Brazil
| | | | - Felipe L de Sá Cavalcanti
- Aggeu Magalhães Institute (IAM), Fundação Oswaldo Cruz (Fiocruz), Recife, Brazil.,Department of Pathology, Institute of Biological Sciences, University of Pernambuco, Recife, Brazil
| | - Gabriel L Wallau
- Aggeu Magalhães Institute (IAM), Fundação Oswaldo Cruz (Fiocruz), Recife, Brazil
| | - Igor V Rocha
- Aggeu Magalhães Institute (IAM), Fundação Oswaldo Cruz (Fiocruz), Recife, Brazil
| | | | - Dyana L Veras
- Aggeu Magalhães Institute (IAM), Fundação Oswaldo Cruz (Fiocruz), Recife, Brazil
| | - Lilian R Alves
- Department of Tropical Medicine, Federal University of Pernambuco, Recife, Brazil
| | | | | | | | | | | | - Danilo E Xavier
- Aggeu Magalhães Institute (IAM), Fundação Oswaldo Cruz (Fiocruz), Recife, Brazil
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Roberto AEM, Xavier DE, Vidal EE, Vidal CFDL, Neves RP, de Lima-Neto RG. Rapid Detection of Echinocandins Resistance by MALDI-TOF MS in Candida parapsilosis Complex. Microorganisms 2020; 8:microorganisms8010109. [PMID: 31940988 PMCID: PMC7023175 DOI: 10.3390/microorganisms8010109] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 01/04/2020] [Accepted: 01/06/2020] [Indexed: 11/16/2022] Open
Abstract
Mass spectrometry by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) was used to identify and differentiate the pattern of susceptibility of clinical isolates of Candida parapsilosis complex. 17 C. parapsilosis sensu stricto, 2 C. orthopsilosis, and 1 C. metapsilosis strains were obtained from blood cultures, and three different inocula (103, 105, and 107 CFU/mL) were evaluated against three echinocandins at concentrations ranging from 0.03 to 16 µg/mL after incubation of 1 h, 2 h, and 3 h. Drug-free control was used. The spectra obtained at these concentrations were applied to generate composite correlation index (CCI) matrices for each yeast individually. After cross correlations and autocorrelations of each spectra with null (zero) and maximal (16) concentrations, the CCI was used as separation parameter among spectra. Incubation time and inoculum were critical factors to reach higher precision and reliability of this trial. With an incubation time of 3 h and inoculum of 107 CFU/mL, it was possible to determine the breakpoint of the clinical yeasts by MALDI-TOF that presented high agreement with the clinical laboratory standard institute (CLSI) reference method. Herein, we show that mass spectrometry using the MALDI-TOF technique is powerful when it exploits antifungal susceptibility testing assays.
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Affiliation(s)
- Ana Emília M. Roberto
- Graduate Program in Fungal Biology, Federal University of Pernambuco (UFPE), Recife-PE 50.740-600, Brazil;
| | - Danilo E. Xavier
- Instituto Aggeu Magalhães, FIOCRUZ, Recife-PE 50.670-420, Brazil;
| | - Esteban E. Vidal
- Center for Strategic Technologies Northeastern (CETENE), Recife-PE 50.740-545, Brazil;
| | | | - Rejane P. Neves
- Graduate Program in Fungal Biology, Federal University of Pernambuco (UFPE), Recife-PE 50.740-600, Brazil;
- Correspondence: (R.P.N.); (R.G.d.L.-N.)
| | - Reginaldo G. de Lima-Neto
- Graduate Program in Fungal Biology, Federal University of Pernambuco (UFPE), Recife-PE 50.740-600, Brazil;
- Correspondence: (R.P.N.); (R.G.d.L.-N.)
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Garcia EF, Luciano WA, Xavier DE, da Costa WCA, de Sousa Oliveira K, Franco OL, de Morais Júnior MA, Lucena BTL, Picão RC, Magnani M, Saarela M, de Souza EL. Identification of Lactic Acid Bacteria in Fruit Pulp Processing Byproducts and Potential Probiotic Properties of Selected Lactobacillus Strains. Front Microbiol 2016; 7:1371. [PMID: 27625647 PMCID: PMC5003889 DOI: 10.3389/fmicb.2016.01371] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2016] [Accepted: 08/18/2016] [Indexed: 12/17/2022] Open
Abstract
This study aimed to identify lactic acid bacteria (LAB) in byproducts of fruit (Malpighia glabra L., Mangifera indica L., Annona muricata L., and Fragaria vesca L.) pulp processing. Fifty strains of LAB were identified using matrix-assisted laser desorption/ionization–time of flight mass spectrometry (MALDI-TOF MS) and 16S rRNA gene sequence (16S rRNA) analysis. Species belonging to Lactobacillus genus were the predominant LAB in all fruit pulp processing byproducts. The average congruency between the MALDI-TOF MS and 16S rRNA in LAB species identification reached 86%. Isolates of L. plantarum, L. brevis, L. pentosus, L. lactis and L. mesenteroides were identified with 100% congruency. MALDI-TOF MS and 16S rRNA analysis presented 86 and 100% efficiency of LAB species identification, respectively. Further, five selected Lactobacillus strains (L. brevis 59, L. pentosus 129, L. paracasei 108, L. plantarum 49, and L. fermentum 111) were evaluated for desirable probiotic-related properties and growth behavior on two different cultivation media. The exposure to pH 2.0 sharply decreased the counts of the different Lactobacillus strains after a 1 or 2 h incubation, while varied decreases were noted after 3 h of exposure to pH 3.0. Overall, the exposure to pH 5.0 and to bile salts (0.15, 0.30, and 1.00%) did not decrease the counts of the Lactobacillus strains. All tested Lactobacillus strains presented inhibitory activity against Staphylococcus aureus, Salmonella Typhimurium, Salmonella Enteritidis, Listeria monocytogenes and Escherichia coli, and presented variable susceptibility to different antibiotics. The selected Lactobacillus strains presented satisfactory and reproducible growth behavior. In conclusion, MALDI-TOF MS and 16S rRNA analysis revealed high efficiency and congruency for LAB species identification, and the selected Lactobacillus strains may be candidates for further investigation of novel probiotic strains.
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Affiliation(s)
- Estefânia F Garcia
- Laboratório de Microbiologia de Alimentos, Departamento de Nutrição, Universidade Federal da Paraíba João Pessoa, Brazil
| | - Winnie A Luciano
- Laboratório de Microbiologia de Alimentos, Departamento de Nutrição, Universidade Federal da Paraíba João Pessoa, Brazil
| | - Danilo E Xavier
- Laboratório de Microbiologia de Alimentos, Departamento de Nutrição, Universidade Federal da Paraíba João Pessoa, Brazil
| | - Whyara C A da Costa
- Laboratório de Processos Microbianos em Alimentos, Departamento de Engenharia de Alimentos, Universidade Federal da Paraíba João Pessoa, Brazil
| | | | - Octávio L Franco
- Laboratório de Genômica e Proteômica, Universidade Católica de Brasília Brasília, Brazil
| | - Marcos A de Morais Júnior
- Grupo Interdepartamental de Pesquisa em Engenharia Metabólica, Departamento de Genética, Universidade Federal de Pernambuco Recife, Brazil
| | - Brígida T L Lucena
- Grupo Interdepartamental de Pesquisa em Engenharia Metabólica, Departamento de Genética, Universidade Federal de Pernambuco Recife, Brazil
| | - Renata C Picão
- Instituto de Microbiologia Paulo Góes, Universidade Federal do Rio de Janeiro Rio de Janeiro, Brazil
| | - Marciane Magnani
- Laboratório de Processos Microbianos em Alimentos, Departamento de Engenharia de Alimentos, Universidade Federal da Paraíba João Pessoa, Brazil
| | - Maria Saarela
- VTT Technical Research Centre of Finland Espoo, Finland
| | - Evandro L de Souza
- Laboratório de Microbiologia de Alimentos, Departamento de Nutrição, Universidade Federal da Paraíba João Pessoa, Brazil
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Ramos PIP, Picão RC, Almeida LGPD, Lima NCB, Girardello R, Vivan ACP, Xavier DE, Barcellos FG, Pelisson M, Vespero EC, Médigue C, Vasconcelos ATRD, Gales AC, Nicolás MF. Comparative analysis of the complete genome of KPC-2-producing Klebsiella pneumoniae Kp13 reveals remarkable genome plasticity and a wide repertoire of virulence and resistance mechanisms. BMC Genomics 2014; 15:54. [PMID: 24450656 PMCID: PMC3904158 DOI: 10.1186/1471-2164-15-54] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Accepted: 12/26/2013] [Indexed: 11/24/2022] Open
Abstract
Background Klebsiella pneumoniae is an important opportunistic pathogen associated with nosocomial and community-acquired infections. A wide repertoire of virulence and antimicrobial resistance genes is present in K. pneumoniae genomes, which can constitute extra challenges in the treatment of infections caused by some strains. K. pneumoniae Kp13 is a multidrug-resistant strain responsible for causing a large nosocomial outbreak in a teaching hospital located in Southern Brazil. Kp13 produces K. pneumoniae carbapenemase (KPC-2) but is unrelated to isolates belonging to ST 258 and ST 11, the main clusters associated with the worldwide dissemination of KPC-producing K. pneumoniae. In this report, we perform a genomic comparison between Kp13 and each of the following three K. pneumoniae genomes: MGH 78578, NTUH-K2044 and 342. Results We have completely determined the genome of K. pneumoniae Kp13, which comprises one chromosome (5.3 Mbp) and six plasmids (0.43 Mbp). Several virulence and resistance determinants were identified in strain Kp13. Specifically, we detected genes coding for six beta-lactamases (SHV-12, OXA-9, TEM-1, CTX-M-2, SHV-110 and KPC-2), eight adhesin-related gene clusters, including regions coding for types 1 (fim) and 3 (mrk) fimbrial adhesins. The rmtG plasmidial 16S rRNA methyltransferase gene was also detected, as well as efflux pumps belonging to five different families. Mutations upstream the OmpK35 porin-encoding gene were evidenced, possibly affecting its expression. SNPs analysis relative to the compared strains revealed 141 mutations falling within CDSs related to drug resistance which could also influence the Kp13 lifestyle. Finally, the genetic apparatus for synthesis of the yersiniabactin siderophore was identified within a plasticity region. Chromosomal architectural analysis allowed for the detection of 13 regions of difference in Kp13 relative to the compared strains. Conclusions Our results indicate that the plasticity occurring at many hierarchical levels (from whole genomic segments to individual nucleotide bases) may play a role on the lifestyle of K. pneumoniae Kp13 and underlie the importance of whole-genome sequencing to study bacterial pathogens. The general chromosomal structure was somewhat conserved among the compared bacteria, and recombination events with consequent gain/loss of genomic segments appears to be driving the evolution of these strains.
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Fehlberg LC, Xavier DE, Peraro PP, Marra AR, Edmond MB, Gales AC. Beta-Lactam Resistance Mechanisms inPseudomonas aeruginosaStrains Causing Bloodstream Infections: Comparative Results Between Brazilian and American Isolates. Microb Drug Resist 2012; 18:402-7. [DOI: 10.1089/mdr.2011.0174] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Lorena C.C. Fehlberg
- Division of Infectious Diseases, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Danilo E. Xavier
- Division of Infectious Diseases, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Paula P. Peraro
- Division of Infectious Diseases, Universidade Federal de São Paulo, São Paulo, Brazil
| | - Alexandre R. Marra
- Division of Infectious Diseases, Universidade Federal de São Paulo, São Paulo, Brazil
- Intensive Care Unit, Hospital Israelita Albert Einstein, São Paulo, Brazil
| | - Michael B. Edmond
- Department of Internal Medicine, Virginia Commonwealth University, Richmond, Virginia
| | - Ana C. Gales
- Division of Infectious Diseases, Universidade Federal de São Paulo, São Paulo, Brazil
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Xavier DE, Picão RC, Girardello R, Fehlberg LCC, Gales AC. Efflux pumps expression and its association with porin down-regulation and beta-lactamase production among Pseudomonas aeruginosa causing bloodstream infections in Brazil. BMC Microbiol 2010; 10:217. [PMID: 20704733 PMCID: PMC2927533 DOI: 10.1186/1471-2180-10-217] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2010] [Accepted: 08/12/2010] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Multi-drug efflux pumps have been increasingly recognized as a major component of resistance in P. aeruginosa. We have investigated the expression level of efflux systems among clinical isolates of P. aeruginosa, regardless of their antimicrobial susceptibility profile. RESULTS Aztreonam exhibited the highest in vitro activity against the P. aeruginosa isolates studied (64.4% susceptibility), whereas susceptibility rates of imipenem and meropenem were both 47.5%. The MexXY-OprM and MexAB-OprM efflux systems were overexpressed in 50.8% and 27.1% of isolates studied, respectively. Overexpression of the MexEF-OprN and MexCD-OprJ systems was not observed. AmpC beta-lactamase was overexpressed in 11.9% of P. aeruginosa isolates. In addition, decreased oprD expression was also observed in 69.5% of the whole collection, and in 87.1% of the imipenem non-susceptible P. aeruginosa clinical isolates. The MBL-encoding genes blaSPM-1 and blaIMP-1 were detected in 23.7% and 1.7% P. aeruginosa isolates, respectively. The blaGES-1 was detected in 5.1% of the isolates, while blaGES-5 and blaCTX-M-2 were observed in 1.7% of the isolates evaluated. In the present study, we have observed that efflux systems represent an adjuvant mechanism for antimicrobial resistance. CONCLUSIONS Efflux systems in association of distinct mechanisms such as the porin down-regulation, AmpC overproduction and secondary beta-lactamases play also an important role in the multi-drug resistance phenotype among P. aeruginosa clinical isolates.
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Affiliation(s)
- Danilo E Xavier
- Division of Infectious Diseases, Universidade Federal de São Paulo, Rua Pedro de Toledo 781, 04039-032 São Paulo, Brazil.
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Carvalhaes CG, Picão RC, Nicoletti AG, Xavier DE, Gales AC. Cloverleaf test (modified Hodge test) for detecting carbapenemase production in Klebsiella pneumoniae: be aware of false positive results. J Antimicrob Chemother 2009; 65:249-51. [PMID: 19996141 DOI: 10.1093/jac/dkp431] [Citation(s) in RCA: 157] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVES The aim of this study was to evaluate the presence of carbapenemases in a Klebsiella pneumoniae collection and the performance of the modified Hodge test (MHT) to correctly identify this phenotype. METHODS Twenty-eight K. pneumoniae clinical isolates with reduced susceptibility to carbapenems were evaluated. Antimicrobial susceptibility and molecular typing were performed by agar dilution and PFGE, respectively. The MHT was performed using both standard and high inoculum of test organisms. Imipenem hydrolysis was investigated by spectrophotometric assays and carbapenemase-encoding genes were identified by PCR and amplicon sequencing. Porin loss was investigated by both PCR and SDS-PAGE. RESULTS Susceptibility rates for imipenem, meropenem and ertapenem were 93%, 57% and 11%, respectively. The PFGE analysis showed seven unrelated genotypes. By testing standard inoculum and ertapenem or meropenem discs, 25% (n = 7) and 21% (n = 6) of the isolates were classified as carbapenemase producers, respectively. When a higher inoculum was employed, these rates increased to 54% (n = 15) and 43% (n = 12), respectively. No imipenem hydrolysis was detected. PCRs identified bla(CTX-M) in 27 (96%) isolates, of which 2 isolates also carried bla(GES-1.) SDS-PAGE and PCR assays revealed that all isolates had lost at least one outer membrane protein, except for a single isolate that was found to express both OmpK35 and OmpK36. CONCLUSIONS False detection of carbapenemase production was observed by the MHT possibly as a result of extended-spectrum beta-lactamase (ESBL) production coupled with porin loss as reported before. Clinical laboratories must be aware of this fact, especially in geographical areas where ESBL-producing isolates are highly prevalent.
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