High prevalence of the plasmid-mediated quinolone resistance determinant qnrA in multidrug-resistant Enterobacteriaceae from blood cultures in Liverpool, UK.
OBJECTIVE
To determine the prevalence of the plasmid-mediated quinolone resistance qnrA gene in a selected collection of blood culture isolates of Enterobacteriaceae resistant to both ciprofloxacin and cefotaxime.


METHODS
Over a 29 month period, a total of 47 non-repetitive isolates of Enterobacteriaceae resistant to both ciprofloxacin and cefotaxime were identified. Isolates were screened for the presence of the qnrA gene, class I integrons and bla(ESBL) by PCR. Transferability was examined by conjugation with the sodium azide-resistant Escherichia coli J53. All qnrA-positive isolates were examined for DNA-relatedness by PFGE.


RESULTS
A total of 15 of the 47 test isolates (32%) were positive for the qnrA gene, and included single isolates of E. coli and Citrobacter freundii, 4 Klebsiella pneumoniae and 9 Enterobacter cloacae. All 15 qnrA-positive isolates carried class 1 integrons, and 11 the extended-spectrum beta-lactamase gene bla(SHV-12). By PFGE two K. pneumoniae and three E. cloacae, respectively, were considered clonally but not temporally related. Plasmid transfer of quinolone resistance was only achieved with single isolates of K. pneumoniae and E. cloacae. Both plasmids carried class 1 integrons with a pSAL-1-like gene cassette arrangement intl1-aadA2-qacEDelta-sul1.


CONCLUSIONS
In this selected group of ciprofloxacin- and cefotaxime-resistant bacteria, carriage of the qnrA gene was high (32%). This compares with <2.0% as demonstrated in worldwide studies of laboratory collections of ciprofloxacin-resistant bacteria. The majority of qnrA-positive isolates in our study originated from high-dependency care units within our hospital, but were shown not to be clonal by PFGE. This is the first report of qnrA-positive Enterobacteriaceae in the United Kingdom.
Corkill
John E
JE
Department of Medical Microbiology, Royal Liverpool University Hospital, Liverpool L7 8XP, UK. jecmm@liverpool.ac.uk
Anson
James J
JJ
Hart
C Anthony
CA
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics; D001769:Blood / Q000382:microbiology*; D002439:Cefotaxime / Q000494:pharmacology; D003227:Conjugation, Genetic; D016172:DNA Fingerprinting; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D016521:Electrophoresis, Gel, Pulsed-Field; D004739:England; D004755:Enterobacteriaceae / Q000187:drug effects* / Q000235:genetics / Q000302:isolation & purification; D004756:Enterobacteriaceae Infections / Q000382:microbiology*; D029968:Escherichia coli Proteins / Q000235:genetics; D022761:Gene Transfer, Horizontal; D006801:Humans; D032023:Integrons / Q000235:genetics; D010957:Plasmids / Q000235:genetics*; D015363:Quinolones / Q000494:pharmacology*; D001618:beta-Lactamases / Q000235:genetics
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C485384:Qnr protein, E coli; C485385:Qnr protein, Klebsiella pneumoniae; D015363:Quinolones; D001618:beta-Lactamases; D002439:Cefotaxime