title: Prevalence of plasmid-mediated quinolone resistance and aminoglycoside resistance determinants among carbapeneme non-susceptible Enterobacter cloacae.
abstract: BACKGROUND
  Simultaneous resistance to aminoglycosides and fluoroquinolones in carbapeneme non-susceptible (CNS) isolates will inevitably create problems. The present study was performed to characterize the prevalence of the plasmid-mediated quinolone resistance determinants (QRDs) and aminoglycoside resistance determinants (ARDs) among the CNS Enterobacter cloacae (E. cloacae) isolates in a Chinese teaching hospital, and to acquire their molecular epidemiological characteristics.
  
  
  METHODS
  The β-lactamases genes (including class A carbapenemase genes bla(KPC) and bla(SME), metallo-β-lactamase genes (MBLs) bla(IMP), bla(VIM) and bla(NDM), and extended spectrum β-lactamases (ESBLs),bla(CTX-M), bla(TEM) and bla(SHV)), QRDs (including qnrA, qnrB, qnrS and aac(6')-Ib-cr) and ARDs (including aac(6')-Ib, armA and rmtB) of these 35 isolates were determined by PCR and sequenced bidirectionally. The clonal relatedness was investigated by pulsed-field gel electrophoresis (PFGE).
  
  
  RESULTS
  Of the 35 isolates, 9 (25.7%) harbored a carbapenemase gene; 23 (65.7%) carried ESBLs; 24 (68.6%) were QRD positive; and 27 (77.1%) were ARD positive. Among the 5 bla(IMP-8) positive strains, 4 (80%) contained both ESBL and QRD genes, and all the 5 (100%) harbored ARD genes. Of the 23 ESBLs positive isolates, 6 (26.1%) were carbapenemase positive, 14 (60.9%) were QRD positive, and 18 (78.3%) were ARD positive. PFGE revealed genetic diversity among the 35 isolates, indicating that the high prevalence of CNS E. cloacae isolates was not caused by clonal dissemination.
  
  
  CONCLUSIONS
  QRD and ARD genes were highly prevalent among the CNS E. cloacae isolates. Multiple resistant genes were co-expressed in the same isolates. The CNS E. cloacae isolate co-expressing bla(NDM-1), bla(IMP-26), qnrA1 and qnrS1 was first reported.
authors.affiliation: Department of Laboratory Medicine, the First Affiliated Hospital of Chongqing Medical University, Chongqing, China.
authors.forename: Shifeng
authors.initials: S
authors.lastname: Huang
authors.forename: Wei
authors.initials: W
authors.lastname: Dai
authors.forename: Shan
authors.initials: S
authors.lastname: Sun
authors.forename: Xiaojiao
authors.initials: X
authors.lastname: Zhang
authors.forename: Liping
authors.initials: L
authors.lastname: Zhang
mesh_terms: D000617:Aminoglycosides / Q000494:pharmacology*; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D015780:Carbapenems / Q000494:pharmacology*; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D016972:Enterobacter cloacae / Q000187:drug effects* / Q000235:genetics*; D010957:Plasmids / Q000235:genetics*; D015363:Quinolones / Q000494:pharmacology*
chemical_list: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; D015780:Carbapenems; D015363:Quinolones