Study on the mechanism of carbapenem resistance in Acinetobacter baumannii

Abstract

Abstract: AIM: To investigate the mechanism of carbapenems resistance in Acinetobacter baumannii in nanchang. METHODS: Nonduplicate carbapenem- resistant A.baumannii (CRAB) isolates collected during 2012 in Second Affiliated Hospital of Nanchang University,strains were identified by vitek-32 automatic microbe analyzer, antimicrobial susceptibility testing by Kirby-Bauer method,AmpC enzyme by three dimensional test,Metallo β-lactamases(MBLs) by EDTA synergy test. Resistance genes were amplified by PCR,the positive results were sequenced to identify the genotype. RESULTS: More than 90% of 84 CRAB isolates were resistant to 9 of 12 antimicrobial agents tested,but the least resistant to cefoperazone-sulbactam(44.0%),and all the strains were multiple drug-resistant. Among the 84 isolates,AmpC enzyme in 83(98.8%) strains was detected,no MBLs-producing strain was found by synergy test. All strains had blaOXA-23, blaOXA-51 and blaADC genes and one had blaOXA-58 gene,while MBLs and blaOXA-24 genes were all negative. The positive rates of adeB,adeS and adeR genes were 98.8%(83/84), 81.0%(68/84) and 67.9%(57/84). The carO gene was found in all isolates,class I intergase gene was detected in 69 isolates,each strain carried ISAba1. CONCLUSION: The drug resistance of CRAB is very severer in nanchang. Production of OXA-23 carbapenemase in A.baumannii is major mechanism of carbapenems resistance in local area. AmpC enzyme, efflux pump AdeABC, class I integron and ISAba1 may be closely related to multidrug resistance of CRAB.

Key words: carbapenems, acinetobacter baumannii, resistance mechanism

CLC Number:

R446.5

WANG Hong, HU Long-hua, NING Chang-xiu, HANG Ya-ping, ZHONG Qiao-shi, HU Xiao-yan, ZHANG Bai-ling, JIA Kun-ru. Study on the mechanism of carbapenem resistance in Acinetobacter baumannii[J]. Chinese Journal of Clinical Pharmacology and Therapeutics, 2014, 19(10): 1093-1098.

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