The first identification of epidemic clone of enterotoxic <italic>Escherichia coli</italic> O∶6 serogroup highly associated with azithromycin resistance in Shanghai

Yuanjun Song; Jiayuan Luo; Min Chen; Hong Liu; Huanyu WU; Yong Chen; Hongyou Chen; Xiaohuan Gong; Chen QI; Sheng Lin; Donglei LU; Zheng’an Yuan; Xuebin XU; Fan WU

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The first identification of epidemic clone of enterotoxic Escherichia coli O∶6 serogroup highly associated with azithromycin resistance in Shanghai

VernacularTitle: 上海地区首次发现和阿奇霉素耐药高度相关的肠产毒性大肠埃希菌O∶6血清群的流行克隆
Author: Yuanjun SONG ¹ ; Jiayuan LUO ¹ ; Min CHEN ¹ ; Hong LIU ¹ ; Huanyu WU ¹ ; Yong CHEN ¹ ; Hongyou CHEN ¹ ; Xiaohuan GONG ¹ ; Chen QI ¹ ; Sheng LIN ¹ ; Donglei LU ¹ ; Zheng’an YUAN ¹ ; Xuebin XU ¹ ; Fan WU ^{1
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Author Information

1. Shanghai Municipal Center for Disease Control and Prevention, Shanghai 200336, China
2. Fudan University Shanghai Medical College, Shanghai 200032, China
Publication Type:Journal Article
Keywords: Enterotoxic Escherichia coli; Phenotypic characteristic; Azithromycin; Resistant clone; Multivariate analysis
From: Chinese Journal of Epidemiology 2019;40(11):1403-1408
CountryChina
Language:Chinese
Abstract: 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.