Molecular characteristics of extended spectrum β-lactamase and carbapenemase genes carried by carbapenem-resistant Enterobacter cloacae in a Chinese university hospital.

Abstract

In recent years, the increase in the prevalence of carbapenem-resistant Enterobacter cloacae (CREC) has been significant and has become a global problem. The aim of this study is to characterize CREC extended spectrum β-lactamases (ESBLs) and CREC carbapenemase genes and evaluate the risk factors for CREC infections in a university hospital in China. The identification and assessment of the antimicrobial susceptibility of CREC isolates were performed using a VITEK-2 compact system. Clonal relatedness was investigated by pulsed-field gel electrophoresis (PFGE). β-Lactamase genes were examined using polymerase chain reaction and nucleotide sequencing. A total of 64 CREC isolates were included in the study. The rate of CREC infections significantly increased between 2009 and 2012. Among the CREC isolates, 39 (60.9%) isolates possessed ESBL genes, and 49 (76.6%) carried carbapenemase genes; blaSHV-12 and blaKPC-2 were the most common genes, respectively. PFGE showed that there were no obvious clonal associations between these CREC isolates, except for 3 isolates. A univariate analysis demonstrated that prior treatment with antibiotics, intravascular catheterization, urinary catheterization, mechanical ventilation, and parenteral nutrition were significant risk factors for CREC infections. The emergence and increase of CREC infections is worrisome. Effective measures should be taken to control the spread of CREC.