Objective We conducted a drug resistance and homology analysis of diarrheagenic Escherichia coli （DEC） in Fengxian District of Shanghai in order to provide a basis for clinical rational drug use， risk monitoring and early warning.
Methods DEC were isolated from diarrheal patients in Fengxian District， Shanghai from 2019 to 2022. The minimum inhibitory concentrations （MIC） of 21 drugs to the DEC were determined. Genotyping and homology analysis were conducted with pulsed-field gel electrophoresis （PFGE）.
Results The DEC detection rate of diarrhea cases was 18.99% （131/690）， including enteroaggregative E.coli （EAEC） 64.89% （85/131）， enterotoxigenic E.coli （ETEC） 22.14% （29/131）， enteropathogenic E.coli （EPEC） 12.21% （16/131）， and enterohemorrhagic E.coli （EHEC） 0.76%（1/131）. The DEC detection showed obvious seasonal characteristics with a high incidence in summer. The DEC multidrug resistance rate was 66.41% with a total of 65 drug resistance profiles. The five antimicrobial drugs with the highest resistance rate were ampicillin （60.31%）， nalidixic acid （51.91%）， cefazolin （50.38%）， tetracycline （44.27%）， and cotrimoxazole （35.11%）. The rate of DEC resistance to levofloxacin was significantly increased from 2019 to 2022. Cluster analysis showed that the similarity of 85 EAEC cluster was 58.4%‒100.0%， and 69 band patterns were obtained. The similarity of 29 ETEC cluster was 58.5%‒100.0%， and 13 band patterns were obtained， including 2 dominant band types. The similarity of 16 EAEC clusters was 53.9%‒100.0%， and 15 band patterns were obtained. Five groups of homologous strains were found， consistent with the resistance phenotypes.
Conclusion Among the diarrhea cases， the DEC epidemic intensity is high， the drug resistance situation is severe， and the risk of outbreak infection is high in Fengxian District， Shanghai. Therefore， health monitoring and prevention need to be strengthened.
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