Molecular epidemiological study and detection of multidrug resistant Acinetobacter baumannii -related resistance genes

Abstract

M. J. Jiang, Sh. P. Zhao, J. M. Li and F. S. Zhang

This study aimed to investigate the existence and molecular epidemiological characteristics of multidrug resistant Acinetobacter baumannii (MDRAB)-related resistance genes isolated from our hospital. Microdilution and disk diffusion methods were used to detect the antibiotic susceptibility of 46 MDRAB isolates that carried OXA-51 gene. Pulsed-field gel electrophoresis (PFGE) was used to analyze the homologies among the strains. Resistance genes were tested through polymerase chain reaction. Among the 46 MDRABA, a total of nine, isolates were categorized as strain A (19.6%), eight as strain B (17.4%), and four as strain O (8.7%). A total of 41 isolates (89.1%) carried the OXA23 gene, 17 (37.0%) carried the PER gene, and six (13%) carried the IMP gene. Six strains (13%) did not carry the membrane pore protein gene carO. The numbers of isolates that carried a particular gene were as follows: 40 (87.0%), armA; 41 (89.1%), ant(3”)-I; 33 (71.7%), aac(3)-I; 2 (4.3%), aac(3)-II; 1 (2.2%), aac(6’)-II; and 1 (2.2%) and aph(3’)-VI. Most of the isolates (93.5%) carried the qacEâÂ?Â?1 gene. These hospital MDRAB isolates were proven to simultaneously carry a variety of drug resistance genes. Strains A and B were the major epidemic strains of nosocomial MDRAB.