耐碳青霉烯类大肠埃希菌分子流行病学研究

Molecular epidemiological study of carbapenem-resistant Escherichia coli

目的调查武汉市三家医院耐碳青霉烯类大肠埃希菌(CREC)耐药基因携带情况及其分子流行病学特点。方法收集2018年7月-2021年5月武汉市第一医院、武汉市中心医院、武汉市黄陂区人民医院共62株临床分离的CREC,采用全自动细菌鉴定及药敏分析系统测定细菌的药物敏感性,碳青霉烯酶诺德曼-珀尔(Carba NP)试验对碳青霉烯酶型确证,全基因组测序分析菌株耐药基因、质粒携带情况以及多位点序列分型(MLST)情况。结果Carba NP试验结果表明,所有菌株产碳青霉烯酶的比例为32.3%(20/62)。20株Carba NP试验阳性菌株均产新德里金属酶(NDM),其中15株产NDM-5,5株产NDM-1,未检出其他碳青霉烯酶耐药基因;所有菌株同时还携带了超广谱β-内酰胺酶基因(bla_(TEM)或bla_(CTX-M))、氨基糖苷类耐药基因aacA、大环内酯类耐药基因(mph或mdf)、甲氧苄啶耐药基因dfrA以及四环素耐药基因tet;20株细菌检出12种序列分型(ST),主要为ST410(n=4)、ST131(n=3)和ST167(n=3),无明显优势菌株;所有菌株都携带1~6个质粒,大多为3~4个。结论本研究检出产NDM的CREC,bla_(NDM)基因在菌株间可能存在克隆传播和水平传播并存的现象。

Objective To reveal the resistance genes prevalence and molecular epidemiological characteristics of the carbapenem-resistant Escherichia coli(CREC)isolates in three hospitals.Methods A total of 62 clinically isolated CREC strains from Wuhan No.1 Hospital,The Central Hospital of Wuhan and Huangpi District People's Hospital from July 2018 to May 2021 were collected.Fully automated bacterial identification and drug susceptibility analysis system was used to determine the drug sensitivity of bacteria.Carbapenemase Nordmann-Poirel(Carba NP) test was used to confirm carbapenicillium type.Whole-genome sequencing was used to analyze the bacterial resistance genes,plasmid carrying status,and multilocus sequence typing(MLST).Results Carba NP test results showed that the proportion of carbapenemase production by all strains was 32.3%(20/62).The 20 Carba NP test-positive strains all produced New Delhi metalloenzyme(NDM);of which,15 produced NDM-5 and 5 produced NDM-1.No other carbapenem resistance genes were detected.All strains also carried extended-spectrum β-lactamase genes(bla_(TEM)or bla_(CTX-M)),aminoglycoside resistance genes aacA,macrolide resistance genes(mph or mdf),trimethoprim resistance gene dfrA and tetracycline resistance gene tet.A total of 12 sequence types(ST)were detected in 20 bacterial strains,mainly ST410(n=4),ST131(n=3)and ST167(n=3),with no obvious dominant strain;all strains carried 1-6 plasmids,mostly 3-4.Conclusion NDM-producing CREC,and the bla_(NDM)gene might coexist with clonal transmission and horizontal transmission among strains.