임상검체로부터 분리된 Acinetobacter baumannii에서 Metallo-β-lactamase 유전자 검출과 Pulsed Field Gel Electrophoresis의 형별

Abstract

We used modified Hodge and EDTA-disk synergy tests for the screening metallo-β-lactamase producing A. baumannii isolated from a lot of imipenem-resistant clinical strains during the period of 2002-2003 in partial University Hospital, Jeonbuk, Korea. We applied PCR to detect the blaIMP-1 and blaVIM-2 gene metallo-β -lactamase. Antimicrobial susceptibility testing was performed by disk diffusion and agar dilution methods according to National Committee for Clinical Laboratory Standards. Metallo-β-lactamase-producing A. baumannii by PCR were detected from 6 strains (7.6%) of 79 A. baumannii, while those were 1.3% in IMP-1 type and 6.3% in VIM-2 type. After DNA fingerprinting pattern of pulsed field gel electrophoresis (PFGE), 2 strains showed the same genotype. The MIC range of imipenem against VIM-2 type imipenem-resistant A. baumannii was 8-32 ㎍/ml, and MIC50 and MIC90 were 8 and 16 ㎍/ml. respectively, but that of imipenem against IMP-1 type A. baumanni was 2 ㎍/ml. To ciprofloxacin, 50% of the metallo-β-lactamase producing A. baumannii were resistant, while all were resistant to ampicillin, cefazolin, cefotaxime and cephalothin. It is concluded from this study that the modified Hodge and EDTA-disk synergy tests are simple tests for screening metallo-β-lactamase-producing A. baumannii, and IMP-1 and VIM-2 metallo-β-lactamase producing A. baumannii strains in Wonkwang University were rarely detected, thus, the PCR-aided rapid detection will be helpful for the early recognition of emerging blaIMP-1 and blaVIM-2 gene positive clinical isolates which demonstrate consistent resistance to carbapenm, and the PFGE method is useful for epidemiological studies of A. baumannii strains.