亚胺培南耐药鲍曼不动杆菌外排泵机制研究

摘要

目的 研究亚胺培南耐药鲍曼不动杆菌(IRAB)耐药性与主动外排泵之间的关系,从而指导临床合理用药及控制院内感染.方法 收集临床分离的IRAB 50株,亚胺培南敏感鲍曼不动杆菌(ISAB) 30株.采用琼脂稀释法检测上述细菌对13种抗菌药物的最低抑菌浓度(MIC),加入外排泵抑制剂Phe-Arg-beta-Naphthylamide (PAβN)观察对亚胺培南MIC变化；脉冲场凝胶电泳(PFGE)分析菌株同源性；聚合酶链反应(PCR)检测adeB、adeR、adeS、adeJ、abeM基因.结果 50株IRAB中MIC50＞ 128 μg/mL的抗菌药物有阿米卡星、环丙沙星、哌拉西林-他唑巴坦、头孢哌酮、头孢西丁、四环素和复方磺胺甲嗯唑,MIC50在32～128 μg/mL的抗菌药物有美罗培南、头孢哌酮-舒巴坦、头孢吡肟、头孢他啶、头孢曲松、头孢噻肟,MIC50＜8μg/mL的抗菌药物有左氧氟沙星和多黏菌素B.对30株ISAB,MIC50＜8μg/mL的药物有美罗培南、阿米卡星、头孢哌酮-舒巴坦、头孢他啶、头孢吡肟、多黏菌素B.加入抑制剂,33株IRAB(66％)对亚胺培南的MIC有4～32倍的降低,ISAB无明显变化.根据PFGE图谱可分为7型,A型为主要流行株.PCR扩增,IRAB的adeB、adeR、adeS、adeJ、abeM基因检出率均＞80％,与ISAB相比,差异有统计学意义(P＜0.01).结论 仁济医院IRAB存在播散流行,且有AdeABC、AdeIJK、AbeM等外排泵广泛存在.%Objective To study the relationship between resistance and active efflux pump in imipenem-resistant Acinetobacter baumannii (IRAB), and guide the rational use of antibiotics and the control of nosocomial infections. Methods A total of 50 IRAB and 30 imipenera-sensitive Acinetobacter baumannii(ISAB)were collected from clinical specimens. The minimum inhibitory concentrations (MIC)to 13 antibiotics were determined by agar dilution method, and the changes of MIC in imipenem by adding Phe-Arg-beta-Naphthylamide(PApN, a kind of pump inhibitor)were observed. Homology was analyzed by pulse-field gel electrophoresis (PFGE). The adeB, adeR, adeS, adej and abeM genes were amplified by polymerase chain reaction (PCR). Results In 50 IRAB, the antibiotics of MIC50 > 128 μg/mL included amikacin, ciprofloxacin, piperacillin-tazobactam, cefoperazone, cefoxitin, tetracycline and sulfamethoxazole. The antibiotics of MIC50 from 32 to 128 μg/mL included meropenem, cefoperazone-sulbactam, cefepime, ceftazidime, ceftriaxone and cefotaxime. The antibiotics of MIC50 <8 μg/mL included levofloxacin and polymyxin B. In 30 ISAB, the antibiotics of MIC50 < 8 μg/mL included meropenem, amikacin, ceftazidime, cefepime, cefoperazone-sulbactam and polymyxin B, The MIC of 33 (66% )IRAB in imipenem decreased 4 to 32 times after adding PApN, while ISAB had no obvious changes. According to PFGE,80 isolates could be classified into 7 types, and type A was the major clone, By PCR amplification, the detection rates of adeB, adeR, adeS, adeJ and abeM genes were > 80% in IRAB. There were significant differences in all genes compared with those of ISAB(P < 0. 01). Conclusions There is an endemic of IRAB in Renji Hospital, and AdeABC, AdeIJK and AbeM efflux pump widely exist.