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|Title: ||Phenotypic and molecular characterisation of carbapenem-hydrolysing class D beta-lactamase-producing Acinetobacter baumannii isolated in Portugal|
|Authors: ||Manageiro, Vera|
the Antibiotic Resistance Surveillance Program in Portugal (ARSIP).
|Keywords: ||Resistência aos Antimicrobianos|
|Issue Date: ||2011|
|Citation: ||Clin Microb Infection. 2011;17(4):S381|
|Abstract: ||Objectives: Acinetobacter baumannii is a ubiquitous pathogen able to cause colonization and both community and healthcare-associated infections. Our purpose was to evaluate the genetic relatedness of carbapenem-hydrolyzing class D b-lactamase (CHDL) producing MDR-Ab from different geographic regions of Portugal. The correlation with carbapenem resistance was also analysed.
Methods: The study included 127 clinical A. baumannii isolates recovered in Portuguese hospitals (116 from Apr2009-Apr2010); 11 from 2005-2008 were included for genetic evolution comparison. The identification of strains was confirmed by PCR (based on the presence or absence of OXA-51-like genes) and antimicrobial susceptibility was screened by TSA and E-test. PCR and sequencing were applied to detect and identify genes encoding CHDLs, class B metallo-b-lactamases (MBL) (blaIMP and blaVIM), and class A b-lactamases (blaTEM, blaSHV and blaCTX-M). Genetic relatedness of MDR-Ab was examined by PFGE and MLST (typing of 25 isolates representative of different PFGE-clusters).
Results: All isolates were MDR but susceptible to colistin. However, the MICs of colistin confirmed one isolate as nonsusceptible. Overall, 77% of the isolates carried blaOXA-23, 18% blaOXA-24, 28% blaTEM-1, 2% blaCTX-M-15-type and 1% blaTEM-110 genes. None of the isolates carried OXA-58 or MBL-encoding genes. All isolates carried the blaOXA-51-type gene, and expressed OXA-66 (98%), OXA-71 (1%) or OXA-104 (1%) CHDL. The blaOXA-104-CHDL gene carries 182 synonymous mutations comparing with the first-described b-lactamase. PFGE analysis revealed that 81 isolates clustered into six clones and 2 presented unique profiles. PFGE profiles were associated with five distinct STs, being ST118 the most frequently encountered, which was found in all 9 hospitals since 2009; this ST was followed by ST92, a single-locus variant (SLV) of ST118, which includes all but one isolate from 2009 and 2010. ST98, also a SLV of ST118, appeared since 2005. The ST187 appeared in 2006 and the novel ST188, appeared in 2009.
Conclusion: This study provides updated data regarding the molecular epidemiology of MDR-Ab in Portugal. Here, we report the first appearance of two epidemic ST OXA-23-producers in the country, ST92 and ST118, suggesting clonal importation; during the study, both STs have successfully spread among all hospitals, suggesting clonal expansion. Indeed, they seem to be replacing the only ST described so far as endemic in Portugal (ST98).|
|Peer Reviewed: ||yes|
|Appears in Collections:||DDI - Posters/abstracts em congressos internacionais|
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