产OXA-23型碳青霉烯水解酶鲍曼不动杆菌基因研究

Studies on the isolates of Acinetobacter baumannii producing OXA-23 carbapenemase

目的 了解临床分离 12株耐碳青霉烯鲍曼不动杆菌的耐药情况、耐药株来源以及产碳青霉烯酶的类型。方法 收集本院对碳青霉烯类药中介或耐药的鲍曼不动杆菌 12株 ,用琼脂稀释法测定最低抑菌浓度(MIC) ,脉冲场凝胶电泳 (PFGE)分析其同源性 ,并用聚合酶链反应 (PCR)检测分析其耐药基因。结果 12株细菌均为多重耐药株 ,有 9株对亚胺培南耐药 ,6株对美罗培南耐药。对青霉素类、头孢菌素类、复方磺胺甲唑均耐药 ,对氟喹诺酮类和酶抑制剂复合物耐药率最低。 12株PFGE图谱分为A、B(B1、B2 ) 2型 ,以A型为主要流行株 (9株 ) ,主要集中在重症监护病房 (ICU)。PCR检出 12株菌株均携带OXA 2 3基因 ,未能检出OXA 2 4基因。结论 本院碳青霉烯类耐药鲍曼不动杆菌流行主要为医院感染所致 ,该流行株呈多重耐药 ,12株菌株均产OXA 2 3型碳青霉烯酶。

Objective To investigate the resistance and homology of carbapenem-resistant Acinetobacter baumannii and the type of carbapenemases. Methods Twelve strains of carbapenem-intermediate and -resistant Acinetobacter baumannii isolated from clinical specimen were analyzed by pulsed-field gel electrophoresis (PFGE). Agar dilution method was made to determine the minimum inhibitory concentrations (MIC) of these strains, and the carbapenemase produced by these strains were detected by polymerase chain reaction (PCR). Results Nine strains were resistant to imipenem, but only six were resistant to meropenem. All strains were resistant to penicillin, cephalosporins, and trimethoprim/sulfamethoxazole, weakly resistant to fluoroquinolones and β-lactams. Twelve strains were classified into Type A and B (B1,B2) according to PFGE pattern. Most of type A strains were isolated from intensive care unit (ICU). Only OXA-23 type gene were detected in these twelve isolates, but no OXA-24 type gene was detected by PCR. Conclusions Carbapenem-resistant A cinetobacter baumannii is the epidemic strain in our hospital from nosocomial infection. They are multi-drug resistant. All strains can produce OXA-23 type carbapenemase.