亚胺培南耐药鲍曼不动杆菌外排泵机制研究

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>128μg/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口恶唑,MIC50在32～128μg/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。

Study on the efflux pump mechanism of imipenem-resistant Acinetobacter baumannii

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 imipenem-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（PAβN,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 MIC50128 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 MIC508 μg/mL included levofloxacin and polymyxin B.In 30 ISAB,the antibiotics of MIC508 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 PAβN,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（P0.01）.Conclusions There is an endemic of IRAB in Renji Hospital,and AdeABC,AdeIJK and AbeM efflux pump widely exist.