摘要
目的 了解上海市某三甲医院阴沟肠杆菌复合体(ECC)临床株的分布及耐药性.方法 收集2018-2020年临床分离的ECC菌株.药敏试验采用肉汤微量稀释法和琼脂稀释法.PCR检测常见碳青霉烯酶耐药基因(blaKPC、blaNDM、blaIMP、blaVIM、blaOXA-48).结果 2018-2020年共分离ECC菌株222株,其中36株分离自普外科,占ECC总菌株的16.2％;标本类型主要为痰液(41.0％)和尿液(20.3％).药敏结果显示ECC菌株对甲氧苄啶-磺胺甲嗯唑、第二代和第三代头孢菌素、氨曲南和喹诺酮类药物耐药率高(31.1％～71.2％),对替加环素、阿米卡星、美西林和头孢他啶-阿维巴坦耐药率低(0.5％～9.0％);对美罗培南和亚胺培南的耐药率分别为9.5％和10.4％.222株ECC菌株中对碳青霉烯类药物不敏感的有34株,其中有23株对碳青霉烯类耐药.经PCR检测碳青霉烯酶基因,34株对碳青霉烯类不敏感ECC菌株中有21株携带碳青霉烯酶基因;包括14株blaNDM、5株blaIMP和2株blaKPC,且均分离自2019和2020年.对碳青霉烯类药物不敏感的34株ECC有73.5％对美西林敏感,包括15株产金属酶的菌株.2019年和2020年ECC临床分离株对亚胺培南和头孢他啶-阿维巴坦的耐药率明显较2018年为高(P＜0.05),且多与产NDM相关.对第三代头孢菌素耐药的ECC菌株中,对亚胺培南和美罗培南的耐药率为20.4％,对阿米卡星和美西林的耐药率分别为4.9％和8.7％;对替加环素的不敏感率为9.7％.结论 2019-2020年ECC临床分离株对碳青霉烯类药物及头孢他啶-阿维巴坦的耐药率上升,与细菌产碳青霉烯酶相关.部分产金属酶的ECC菌株对美西林敏感.
Abstract
Objective To investigate the distribution and antimicrobial resistance of Enterobacter cloacae complex(ECC)isolated from a tertiary hospital in Shanghai.Methods Clinical ECC isolates were collected from 2018 to 2020.Antimicrobial susceptibility test was performed with broth microdilution and agar dilution methods.PCR was applied to detect five carbapenemase genes(blaKPC,blaNDM,blaIMP,blaVIM and blaOXA-48).Results A total of 222 ECC isolates were collected from 2018-2020,including 36 strains(16.2％)from general surgery department.The strains were mainly isolated from sputum(41.0％)and urine(20.3％).MIC results showed that the isolates were highly resistant to trimethoprim-sulfamethoxazole,the second-and third-generation cephalosporins,aztreonam and quinolones(31.1％-71.2％resistant),but low resistance rates to tigecycline,amikacin,mecillinam,and ceftazidime-avibactam(0.5％-9.0％resistant).About 9.5％and 10.4％of the strains were resistant to meropenem and imipenem,respectively.A total of 34 ECC strains were carbapenem-nonsusceptible strains,of which 23 strains were resistant to carbapenems.Among the 34 carbapenem-nonsusceptible strains,25(73.5％)strains were susceptible to mecillinam,including 15 strains producing metallo-β-lactamase.PCR assay identified carbapenemase genes in 21 of the 34 carbapenem-nonsusceptible strains,including blaNDM(14 strains),blaIMP(5 strains)and blaKPC(2 strains).Compared with the strains isolated in 2018,the ECC strains isolated in 2019 and 2020 showed significantly higher resistance rates to imipenem and ceftazidime-avibactam(P＜0.05),primarily associated with the production of NDM.Among the ECC strains resistant to third-generation cephalosporins,20.4％were resistant to imipenem and meropenem,while 4.9％and 8.7％were resistant to amikacin and mecillinam,respectively,and 9.7％were nonsusceptible to tigecycline.Conclusions The ECC isolates in 2019 and 2020 showed increasing resistance rates to carbapenems and ceftazidime-avibactam due to the production of metallo-β-lactamases.Some of the metallo-β-lactamase-producing ECC isolates were susceptible to mecillinam.
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