多药耐药鲍曼不动杆菌AdeB外排系统与碳青霉烯类耐药的关系

目的 探讨我国多药耐药鲍曼不动杆菌（鲍氏不动杆菌,MDR-AB）AdeB外排系统对碳青霉烯类抗生素耐药的介导作用.方法 选取全国21家医院MDR-AB菌株101株和敏感菌株12株,用琼脂稀释法检测外排泵抑制剂苯丙氨酸-精氨酸-β-苯胺（PAβN,50 mg/L）对菌株AdeB外排系统的抑制作用及菌株对亚胺培南和美罗培南的耐药情况.利用实时荧光定量PCR技术分析adeB的表达情况,并探讨其与外排表型及耐药之间的关系.结果 101株MDR-AB对亚胺培南和美罗培南的耐药率分别为62.4％和52.5％.1 13株菌株中,共有82株adeB阳性菌株,其中adeB表达比率＞2.5的7株菌株均表现为多重耐药.亚胺培南的耐药组和非耐药组adeB的表达比率分别为1.237±0.159和0.698±0.115,差异有统计学意义（t=2.641,P＜0.05）；而美罗培南耐药组和非耐药组adeB的表达比率分别为1.013±0.148和0.978±0.150,组间差异无统计学意义（t=0.166,P＞0.05）.结论 我国MDR-AB中,AdeB外排泵系统的过度表达介导了其对亚胺培南耐药,并可能和美罗培南耐药有关.

The relationship between AdeB efflux system of multidrug resistant Acinetobacter baumannii and carbapenem resistance

Objective To investigate the role of AdeB efflux system of multidrug resistant Acinetobacter baumannii （MDR-AB） in carbapenem resistance.Methods One hundred and one isolates of MDR-AB and 12 isolates of antibiotic susceptible Acinetobacter baumannii were collected from 21 hospitals in China.Agar dilution method was used to evaluate the inhibitory effect of efflux pump inhibitor phenyl-arginine-β-naphthylamide （PAβN,50 mg/L） on AdeB-mediated efflux and the drug resistance of MDR-AB to imipenem and meropenem.Real time-PCR was used to determine the expression of adeB gene.Results The resistance rates of 101 MDR-AB isolates to imipenem and meropenem were 62.4% and 52.5%,respectively.Of 113 isolates,82 were adeB gene positive,7 of which showed significantly high adeB expression （expression rate 〉2.5） and were all MDR-AB.The ratio of adeB expression was significantly different between resistant isolates （1.237±0.159） and susceptible isolates （0.698±0.115） of imipenem （t=2.641,P〈0.05）,but no significant difference was noted between resistant isolates （1.013±0.148） and susceptible isolates （0.978±0.150） of meropenem （t=0.166,P〉0.05）.Conclusions The over expression of AdeB efflux pump may play a role in imipenem resistance in MDR-AB but its effect on meropenem resistance is uncertain.