Published in:
Open Access 01-12-2013 | Research
Outbreak of multidrug-resistant Klebsiella pneumoniae carrying qnrB1 and bla CTX-M15 in a French intensive care unit
Published in: Annals of Intensive Care | Issue 1/2013
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Background
The prevalence of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae is increasing globally and is a major clinical concern. Between June 2008 and September 2009, 4% of patients in an intensive care unit (ICU) were found to be colonized or infected by strains of Klebsiella pneumoniae multiresistant to ceftazidime, ciprofloxacin, and tobramycin; an investigation was initiated and isolates were characterized by molecular typing and resistance patterns.
Methods
Antibiotic susceptibilities were determined by Vitek2®, Etest®, and agar dilution. Gene encoding beta-lactamases and plasmid-mediated quinolone resistance PMQR determinants (qnr, aac(6′)-Ib) were characterized by PCR, sequencing, and transfer assays. DiversiLab® fingerprints were used to study the relatedness of isolates.
Results
Fourteen isolates co-expressing blaCTX-M15, qnrB1, and aac(6′)-Ib-cr were identified. Genotypic analysis of these isolates identified 12 clonally related strains recovered from 10 patients. The increased prevalence of blaCTX-M15-qnrB1-aac(6′)-Ib-cr-producing K. pneumoniae coincided with the presence in the ICU of a patient originally from Nigeria. This patient was infected by a strain not clonally related to the others but harbouring qnrB1 and aac(6′)-Ib-cr genes, a finding not hitherto observed in France. We suspected transmission of resistance plasmids followed by rapid dissemination of the multiresistant K. pneumoniae clone by cross-transmission.
Conclusion
This study highlights the importance of microbiological screening for multidrug-resistant strains in ICUs, particularly among patients from regions in which multidrug-resistant bacteria are known to exist.