获得性金属β-内酰胺酶初筛方法的研究

Methods Screening Acquired Metallo-β-lactamases

目的 探讨并建立适用于临床微生物实验室常规初筛检测获得性金属 β 内酰胺酶 (MBL)的实验方法 ,为监控产酶株的流行及指导临床合理选择抗生素提供依据。方法 以EDTA和巯基乳酸 (TLA)为MBL的抑制剂 ,以亚胺培南 (IPM)和头孢他啶 (CAZ)为MBL的底物 ,采用纸片协同法和复合纸片法作MBL初筛试验 ,将几种初筛试验的结果与聚合酶链反应 (PCR)的结果进行比较分析。结果 应用PCR法 ,在 10 2株耐IPM和 (或 )CAZ铜绿假单胞菌中检出VIM型MBL阳性株 11株 ,其中 1株经DNA测序证实为VIM 2亚型 ;几种初筛试验中 ,IPM EDTA复合纸片法的阳性预测值 (90 9% )和阴性预测值 (98 9% )最高 ,敏感性 (90 9% )和特异性 (98 9% )都 >90 %。结论 IPM EDTA复合纸片法方法简便、结果可靠 。

OBJECTIVE To explore and establish a method for screening acquired metallo β lactamases (MBL) in clinical microbiology laboratory. METHODS Clinical isolates of Pseudomonas aeruginosa with a reduced susceptibility to imipenem (IPM) and/or ceftazidime (CAZ) were subjected to PCR analyses with primers specific to blaIMP and blaVIM. In addition, the double disk synergy test and the inhibitor potentiated disk diffusion test, using two kinds of substrate inhibitor combinations (ceftazidime thiolactic acid (CAZ TLA) and imipenem EDTA (IPM EDTA), were investigated and the results were evaluated with those of PCR analyses. RESULTS Among 102 test strains, 11 were positive in PCR analyses with blaVIM primers, and one of them had been identified as VIM 2 by DNA sequence. The inhibitor potentiated disk diffusion test using IPM EDTA showed high sensitivity (90 9%), specificity (98 9%) and predictive value (positive predictive value: 90 9%, negative predictive value: 98 9%). CONCLUSIONS The inhibitor potentiated disk diffusion test using IPM EDTA is a convenient and credible method for detecting acquired MBL producer in clinical microbiology laboratory.