Characterization of drug-resistance and molecular epidemiology of Enterobacter cloacae among patients with clinical infections in a teaching hospital, China

A total of 114 non-repetitive Enterobacter cloacae isolates were collected from patients with clinical infections and tested for susceptibility to 15 antimicrobials. Enterobacterrepetitive intergenic consensus (ERIC) analysis was used to determine the genetic relatedness between isolates with enzymes. Touchdown polymerase chain reaction (PCR) and single PCR were used to detecting the genes encoding beta-lactamase (single PCR rechecked) and integron, aac-(6’)-Ib, respectively. Transferability of drug-resistant was studied by conjugation experiments. 41.2% strains possessed one or two AmpC β-lactamase genes, and 29.8% isolates harbored one or more broad-spectrum beta-lactamase genes. While aac(6’)-Ib was detected in six isolates. 26 isolates were detected with class1 integron and four different gene cassettes were found in these strains. None of isolate was carbapenemase producer. Patients with these bacterial infections suffered a failure of different cephalosporin treatment in clinical. The presence of producing ESBLs, AmpC β-lactamase was correlated with the reduced susceptibility to carbapenems among E. cloacae. In addition, these genes could transmit between different species by plasmids and enhanced by insertion sequences. ERIC revealed 11 unrelated profiles, which indicated that there was scattered transmission among E. cloacae with enzymes in the hospital environment, even acrossed more than three years.   Key words: Enterobacter repetitive intergenic consensus, integron, plasmid, resistance.