Distribution of carbapenemases and efflux pump in carbopenems-resistance Acinetobacter baumannii

Acinetobacter baumannii has emerged as an important pathogen related to serious infections and nosocomial outbreaks around the world. The aim of this study was to detect the distribution of carbapenemases and efflux pump in carbopenems-resistance Acinetobacter baumannii (CRAB) . In this study, 100 isolates of CRAB were collected from clinical specimens. Agar dilution was conducted to determine the minimum inhibitory concentrations (MICs) to 15 kinds of antibiotic. Genes of carbapenemases and efflux pumps were amplified by PCR. The expression difference of pump genes was also analyzed by real-time PCR between CRAB and carbopenems- sensitive Acinetobacter baumannii (CSAB). We found that most antibiotics, including aminoglycosides, fluoroquinolones and cephalosporins showed high MIC values in CRAB. While, all isolates were sensitive to polymyxin B. Among CRAB, 54, 32 and 16 isolates were positive for SHV-12，PER-1 and TEM-1, respectively. 86 isolates were positive for OXA-23. 55, 33 and 5 isolates carried adeB, adeJ and adeE genes. The expression level of adeB in CRAB was ten times higher than that in CSAB. Moreover, isolates with single adeE gene were detected for the first time in Acinetobacter baumannii .