2019—2021年上海市腹泻儿童肠集聚性大肠埃希菌的病原学特征分析

Analysis of pathogenic characteristics of enteroaggregative Escherichia coli in children with diarrhea in Shanghai from 2019 to 2021

【目的】了解上海市腹泻儿童肠集聚性大肠埃希菌(EAEC)毒力基因携带情况、分子分型特征及抗生素的敏感性,为EAEC监测及EAEC感染的规范治疗提供科学依据。【方法】以上海市6个行政区腹泻儿童(≤5岁)的EAEC菌株作为研究对象。用实时荧光定量聚合酶链反应(PCR)检测EAEC毒力基因,采用脉冲场凝胶电泳(PFGE)进行分子分型,应用微量肉汤稀释法进行药敏试验。采用χ^(2)检验和两独立样本t检验比较郊区和市区来源EAEC毒力基因及耐药性的差异。【结果】2019—2021年59株EAEC的3种毒力基因aggR、pic、astA检出率依次为30.5%、50.8%、57.6%,郊区和市区来源EAEC毒力基因检出率差异无统计学意义(P>0.05)。PFGE溯源分析结果显示,仅有2株EAEC属于同一型别且采集自同一家医院,带型呈多态性。EAEC对亚胺培南、多黏菌素E敏感,对复方新诺明、氨苄西林、萘啶酸、四环素的耐药率(93.1%、79.3%、63.8%、58.6%)高于50.0%。郊区和市区来源EAEC对头孢唑林、头孢噻肟、环丙沙星的耐药率存在差异(P<0.05)。多重耐药菌共有47株,最常见的多重耐药菌耐药谱为氨苄西林-复方新诺明-萘啶酸,郊区和市区间多重耐药EAEC数量差异无统计学意义(P>0.05)。【结论】上海市6个行政区腹泻儿童EAEC毒力基因组合具有多样性,分子分型带型较分散,可能存在同源菌株交叉感染。菌株耐多药现象比较普遍,市区和郊区来源EAEC对头孢唑林、头孢噻肟、环丙沙星的耐药率存在差异。应重视临床抗生素的规范使用,有效阻断EAEC多重耐药菌的传播。

[Objective]To understand the presence of virulence genes,molecular typing characteristics,and antibiotic sensitivity of enteroaggregative Escherichia coli(EAEC)in children with diarrhea in Shanghai,so as to provide a scientific basis for EAEC monitoring and standardized treatment of EAEC infection.[Methods]EAEC strains isolated from children(≤5 years old)with diarrhea in six districts of Shanghai were collected as the study subjects.EAEC virulence genes were detected by real-time fluorescence quantitative PCR,molecular typing was performed by pulsed-field gel electrophoresis(PFGE),and drug susceptibility tests were conducted using the microbroth dilution method.χ^(2)test and two independent samples t-test were used to compare the differences in virulence genes and antibiotic resistance between suburban and urban EAEC strains.[Results]From 2019 to 2021,the overall detection rates of gene aggR,pic and astA of 59 EAEC were 30.5%,50.8%,and 57.6%,respectively.There was no significant difference in the detection rates of virulence genes between suburban and urban EAEC strains(P>0.05).PFGE analysis revealed that only two EAEC strains belonged to the same PFGE pattern and were collected from the same hospital,and the overall PFGE patterns were polymorphic.EAEC showed susceptibility to imipenem and colistin E,and the resistance rates to sulfamethoxazole(SXT),ampicillin(AMP),nalidixic acid(NAL),and tetracycline(93.1%,79.3%,63.8%,and 58.6%,respectively)were higher than 50.0%.The antibiotic resistance rates of cefazolin(CFZ),cefotaxime(CTX),and ciprofloxacin(CIP)were significantly different between EAEC strains from suburban and urban areas(P<0.05).A total of 47 strains exhibited multi-drug resistance,with the most common resistance spectrum being AMP-SXT-NAL.There was no statistically significant difference in the number of multidrugresistant EAEC strains between suburban and urban areas(P>0.05).[Conclusion]The EAEC virulence gene assemblages in children with diarrhea in the six districts of Shanghai are diverse,and the molecular typing patterns are relatively scattered,indicating possible crossinfection of homologous strains.Multi-drug resistance in EAEC strains is relatively common,and there is a statistically significant difference in the resistance rates of CFZ,CTX and CIP between urban and suburban EAEC strains.Attention should be given to standardizing the use of clinical antibiotics to effectively control the dissemination of multidrug-resistant EAEC strains.