Prevalence of Qnr determinants among bloodstream isolates of Escherichia coli and Klebsiella pneumoniae in a Taiwanese hospital, 1999-2005.
OBJECTIVE
To determine the prevalence and characteristics of bloodstream isolates of Escherichia coli and Klebsiella pneumoniae with qnr genes in a Taiwanese hospital.


METHODS
A total of 2035 E. coli and 1147 K. pneumoniae isolates collected between 1999 and 2005 were screened for qnrA, qnrB and qnrS by PCR and colony hybridization. Beta-lactamase genes, genetic relatedness and transferability were examined by PCR, PFGE and conjugation, respectively.


RESULTS
The prevalence of qnr genes was 7.8% and 0.6% for K. pneumoniae and E. coli, respectively. The prevalence rates of qnrB2, qnrB4 and qnrS1 genes for K. pneumoniae were 2.3%, 3.6% and 2.8%, respectively, and for E. coli were 0.2%, 0% and 0.4%, respectively. The prevalence of qnrB4 in K. pneumoniae increased remarkably from 0% to 7.6% over the 7 study years. qnrA was not detected. Overall, the SHV-5-related, CTX-M-14, CTX-M-3, CMY-2, DHA-1 and IMP-8 beta-lactamases were detected alone or in combination in 82.0% of qnr-positive K. pneumoniae isolates and 41.7% of qnr-positive E. coli isolates. Notably, all qnrB4-positive isolates possessed the DHA-1 enzyme, and the majority of the qnrB2-positive isolates (E. coli, 100%; K. pneumoniae, 80.8%) produced SHV-5-related beta-lactamases. Genetic diversity was demonstrated by PFGE. Conjugation experiments revealed co-transfer of bla(SHV-12), bla(DHA-1) and bla(SHV-5) with qnrB2, qnrB4 and qnrS1, respectively.


CONCLUSIONS
qnr genes remained rare in E. coli but appeared to be increasing in K. pneumoniae in our hospital. Horizontal transfer may play a major role in the intra-hospital spread of qnr.
Wu
Jiunn-Jong
JJ
Department of Medical Laboratory Science and Biotechnology, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan.
Ko
Wen-Chien
WC
Wu
Hsiu-Mei
HM
Yan
Jing-Jou
JJ
D016470:Bacteremia / Q000382:microbiology*; D001426:Bacterial Proteins / Q000235:genetics*; D003227:Conjugation, Genetic; D003428:Cross Infection / Q000382:microbiology; D004269:DNA, Bacterial / Q000235:genetics; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D016521:Electrophoresis, Gel, Pulsed-Field; D004926:Escherichia coli / Q000235:genetics* / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000382:microbiology; D029968:Escherichia coli Proteins / Q000235:genetics*; D006761:Hospitals; D006801:Humans; D007525:Isoelectric Focusing; D007710:Klebsiella Infections / Q000382:microbiology; D007711:Klebsiella pneumoniae / Q000235:genetics* / Q000302:isolation & purification; D008826:Microbial Sensitivity Tests; D013624:Taiwan; D018440:beta-Lactam Resistance / Q000235:genetics; D001618:beta-Lactamases / Q000145:classification / Q000235:genetics / Q000302:isolation & purification
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C485384:Qnr protein, E coli; C485385:Qnr protein, Klebsiella pneumoniae; D001618:beta-Lactamases