High rates of plasmid-mediated quinolone resistance QnrB variants among ciprofloxacin-resistant Escherichia coli and Klebsiella pneumoniae from urinary tract infections in Korea
Abstract number: P2089
Shin J.H., Jung H.J., Lee J.Y., Kim H.R., Lee E.Y., Chang C.L., Lee J.N.
Objectives: The aims of this study were to investigate the prevalence of qnrA, qnrB, and qnrS determinants and their molecular characteristics in ciprofloxacin-resistant isolates of Escherichia coli and Klebsiella pneumoniae from urinary tract infections in Korea.
Methods: A total of 202 non-duplicated clinical isolates of ciprofloxacin-resistant E. coli (N=143) and K. pneumoniae (N=59) were collected from urinary tract infections between July 2005 and Aug. 2006. The qnr determinant screening was carried out by PCR amplification of qnrA, qnrB, and qnrS; and all positive results were confirmed by direct sequencing of the PCR products. For qnr-positive strains and their conjugants, antimicrobial susceptibility tests and pulsed-field gel electrophoresis were performed.
Results: The qnrB gene was detected in 41 of the 202 isolates. Among 33 of 59 (55.9%) K. pneumoniae isolates showing qnrB, 29 isolates contained the qnrB4 gene, 3 isolates had the qnrB2 gene, and 1 isolate had the qnrB6 gene. All 8 (5.6%) of the qnrB-positive isolates among the 143 E. coli strains possessed the qnrB4 gene. The MICs of ciprofloxacin for the transconjugants were 0.03 to 2 ug/ml, representing an increase of 4 to 256 fold relative to the recipient, E. coli J53Azr. Resistances to various other antimicrobial agents also were transferred with the plasmid. The PFGE analysis revealed indistinguishable or closely related patterns in several strains, and highly diverse patterns in general.
Conclusions: qnrB variants, especially the qnrB4 subtype, are highly prevalent in ciprofloxacin-resistant E. coli and K. pneumoniae from urinary tract infections in Korea. The emergence of plasmid-mediated quinolone resistance may contribute by several means to the rapid increase in bacterial resistance to these drugs. Thus, we are paying close attention to the course of plasmid-mediated qnr resistance in various clinical specimens of Enterobacteriaceae.
|Session name:||18th European Congress of Clinical Microbiology and Infectious Diseases|
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