1. C1-109
48th Interscience Conference on Antimicrobial Agents and Chemotherapy
October 25-28, 2008.
Washington, USA
Emergence of VIM-2 Metallo--lactamase in Welsh Hospitals. M. WOOTTON1, R. SOUTAR1, M. A. TOLEMAN2, T. R. WALSH2 and R. A. HOWE1 1NPHS Microbiology, University Hospital Wales, Cardiff, United Kingdom, 2Medical Microbiology, Cardiff University, Cardiff, United Kingdom
Introduction
Materials and Methods
Results
Pseudomonas aeruginosa (PSA) is an important pathogen affecting patients in intensive care facilities. Carbapenem resistance in these isolates have an obvious impact on clinical decisions and is a growing concern. Metallo β-lactamases (MBLs) hydrolyse all β-lactams except aztreonam. There are now several types of MBL on mobile elements; VIM and IMP are the most prevalent worldwide, and there is concern about their spread both between PSA and into other bacteria including Enterobacteriaceae. The prevalence of carbapenem resistance in PSA is 6.8% in the UK as compared to 12.4% in Wales. This is largely due to efflux and porin loss, although VIM and IMP MBLs have been found in England. Here we report the emergence of the MBL VIM-2 in PSA isolated in two hospitals in Wales
Two isolates of PSA were cultured from the respiratory secretions of 2 patients in the ICUs of separate hospitals. Susceptibilities were established using the Phoenix automated ID/AST system and Etest. The phenotypic presence of MBLs was determined by Etest using standard protocols and PCR assays were performed for SHV, KPC, GES, IMP, VIM and OXA genes using specific primers. The presence of the blaVIM-2 gene and the class 1 integron variable region was analysed by PCR and sequencing. Isolates were typed using pulsed field gel electrophoresis (PFGE) and in-gel hybridisation using S1 and I-Ceu-1 digested plugs.
Both isolates were resistant to all agents tested except amikacin and colistin; MICs of imipenem, meropenem and aztreonam were >16mg/L (Table 1). Phenotypic tests for MBLs were positive for both strains and showed identical PFGE profiles (Picture 1). Only VIM and OXA PCR results were positive for both strains. The integron variable region consisted of dhfr, blaOXA-10, blaVIM-2, aac6’IIb genes. Hybridisation results indicated that the VIM gene was chromosomally encoded (Picture 2).
aGI= Glycopeptide intermediate
Picture 2: Genetic locus of Welsh blaVIM-2 genes
intI1
blaVIM-2
qacEΔ1/sul
aacA4
oxa-10
arr-2
Picture 1: Phenotypic and genotypic analysis.
intI1
blaVIM-2
qacEΔ1/sul
aacA4
oxa-10
arr-2
Conclusions
This is the first report of the VIM MBL emerging in PSA in welsh hospitals.
The clonal nature of the two isolates is indicative of dissemination of a specific clone within two hospitals.
The prevalence of MBLs in Wales is unknown and further surveillance is needed to determine the frequency of MBLs in PSA in Wales.
Table 1: Preliminary phenotypic and genotypic testing
VIM
OXA
PFGE
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