16S rRNA methylase containing Enterobacteriaceae in the SENTRY Asia-Pacific region frequently harbour plasmid-mediated quinolone resistance and CTXM types

Abstract number: O559

Bell J.M., Andersson P., Jones R., Turnidge J.

Objectives: 16S rRNA methylases and plasmid-mediated quinolone resistance (PMQR) genes have recently emerged as important resistance mechanisms to aminoglycosides and fluoroquinolones respectively. We examined all 16S rRNA methylase containing Enterobacteriaceae from the Asia-Pacific region (2007–2008) for the presence of PMQR and CTX-M-types, which are already known as a world-wide problem.

Methods: Enterobacteriaceae collected from 10 countries as part of the SENTRY Antimicrobial Surveillance Program during 2007–2008 showing elevated aminoglycoside resistance (amikacin MIC geqslant R: gt-or-equal, slanted64 mg/L, and gentamicin and tobramycin geqslant R: gt-or-equal, slanted16 mg/L) were tested for the 16S rRNA methylase genes (armA, rmtB, and rmtC) by real-time PCR. Isolates positive for 16S rRNA methylase genes were also screened for presence of PMQR genes (qnrA, qnrB, qnrS, aac(6')Ib-cr, qepA), and CTX-M encoding genes, using real-time PCR.

Results: 16S rRNA encoding genes were detected in 209 of 4,161 isolates from 5 countries: China (107, 6.9%); India (71, 10.5%); Hong Kong (3, 1.5%); Korea (17, 6.1%), Taiwan (11, 5.0%), among 9 species. armA was found in 136 strains and rmtB in 60 strains; each were observed in all 5 countries. rmtC carrying isolates (n = 13) were only from India, observed in 5 species, where previously only described in Proteus mirabilis. 91.4% of all 16S rRNA methylase containing isolates also had either PMQR genes: qnr (n = 79, 38%); aac(6')Ib-cr (n = 66, 32%); qepA (n = 20, 10%), or CTX-M genes (n = 158, 76%). qepA was found in India and China, exclusively with rmtB and predominantly in Escherichia coli. Multiple PMQR resistance mechanisms was surprisingly frequent, with 32 (15.3%) isolates containing two PMQR genes, predominantly qnr in combination with aac(6')Ib-cr. Close to 50% of all 16S rRNA methylase containing isolates also harboured a PMQR gene in combination with CTX-M types.

Conclusion: These results highlight the increasing problem of multiple-drug resistance among clinical isolates in the Asia-Pacific region, and the importance of vigilant surveillance programs to monitor emerging resistance trends.

Session Details

Date: 10/04/2010
Time: 00:00-00:00
Session name: Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases
Location: Vienna, Austria, 10 - 13 April 2010
Presentation type:
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