Objective: To investigate the molecular characterization of adult diarrhea cases caused by enterotoxic Escherichia coli (ETEC) and explore the practical model of epidemiology for laboratory technique and data needs based on the surveillance network. Methods: Epidemiological design and sampling targeted adult cases ETEC caused diarrhea in epidemic season. The enterotoxin type, serogroup, resistance, colonization factor and molecular type of ETEC were identified. Multiple dynamic phenotypic characteristics of ETEC were indicated by multidimensional and multivariable data. Results: From 2016 to 2018, 84 eligible ETEC strains were detected. The dominant serums/toxins were O∶6 (STh), O∶25 (LT), O∶159 (STh), O∶153 (STh). O∶6 (STh+CS21), which replaced O∶25 and O∶159 as the popular clones in 2018. Six cases of O∶153 (STh+CFA/I+CS8+PT34) in outbreak in 2017 were imported ones. The resistance rates of ETEC strains detected in adults to sulfasoxazole, naproxinic acid, ampicillin and azithromycin were more than 30%, multidrug resistance (MDR) reached 58.3%. Serum/toxin types suggested that attenuated strains were more likely to become MDR. Molecular typing confirmed that the genetic similarity of the dominant clone of O∶6 serogroup (PT20-24) was higher than O∶25 and O∶159. There was a high correlation between the minimal inhibitory concentration (MIC) of azithromycin and the resistant gene mphA (87.5%, 28/32). O∶6 (STh+CS21+mphA) resistant clone was first detected in 2016. Conclusion: A new epidemic clone in adult ETEC diarrhea cases in Shanghai was O∶6 (STh+CS21+mphA). For the first time the association between azithromycin resistance gene mphA and a serum group of ETEC was observed. Multidimensional and multivariate analysis techniques based on epidemiology can help reveal the potential transmission pattern of ETEC for the accurate surveillance and early warning of outbreaks.
目的： 基于监测网络对肠产毒性大肠埃希菌（ETEC）成年人腹泻病例开展分子特征研究，探索流行病学对实验室技术和数据需求的实践模式。 方法： 以ETEC腹泻流行季节的成年人病例为对象进行流行病学设计和抽样，鉴定肠毒素型、血清群、耐药表型、定殖因子及分子型，通过多维度与多变量数据展示获得ETEC多个动态表型特征。 结果： 2016－2018年监测网络符合条件的ETEC病例84株。优势血清/毒素型依次为O∶6（STh）、O∶25（LT）、O∶159（STh）、O∶153（STh），O∶6（STh+CS21）取代O∶25和O∶159成为2018年的流行克隆，2017年的6例O∶153（STh+CFA/I+CS8+PT34）为输入型暴发案例；成年人ETEC耐药率超过30%有磺胺异恶唑、萘啶酸、氨苄青霉素和阿奇霉素，多重耐药菌（MDR）达58.3%，血清/毒素型别提示弱毒株易形成MDR；分子分型证实O∶6血清群优势克隆（PT20~24）的遗传相似度超过O∶25和O∶159，且与阿奇霉素最低抑菌浓度（MIC）和耐药基因mphA间存在高度相关性（87.5%，28/32），O∶6（STh+CS21+mphA）耐药克隆始于2016年。 结论： 上海地区ETEC成年人腹泻病例新的流行克隆为O∶6（STh+CS21+mphA），首次观察到阿奇霉素耐药基因mphA和ETEC某个血清群存在关联。基于流行病学构建的多维度和多变量分析技术，有助揭示ETEC潜在传播规律，达到精准监测和预警暴发目的。.
Keywords: Azithromycin; Enterotoxic Escherichia coli; Multivariate analysis; Phenotypic characteristic; Resistant clone.