[Epidemiological characteristics of diarrheagenic Escherichia coli among diarrhea outpatients in China, 2012-2015].

Objective To understand the epidemiological characteristics of diarrheagenic Escherichia (E.) coli (DEC) among diarrhea outpatients in China. Methods Diarrhea surveillance program was conducted in outpatient and emergency departments from 170 hospitals that under the sentinel programs in 27 provinces, from 2012-2015. Clinical and epidemiological data regarding diarrhea patients were collected, with fecal specimens sampled and tested for DEC in 92 network-connected laboratories. Results Among all the 46 721 diarrhea cases, 7.7% of them appeared DEC positive in those with geographic heterogeneity. In 2 982 cases (6.4%) with available data on PCR subtypes of DEC, enteroaggregative E. coli (EAEC, 1 205 cases, 40.4%) appeared the most commonly seen pathogens, followed by enteropathogenic E. coli (EPEC, 815 cases, 27.3%), and enterotoxigenic E.coli (ETEC, 653 cases, 21.9%). The highest positive rate of DEC was observed in outpatients of 25-34 years old (10.1%), living in the warm temperate zones (11.1%), and with mucous-like stool (9.4%). The positive rate of DEC showed a strong seasonal pattern, with peaks in summer, for all the subtypes. Conclusions DEC seemed easy to be detected among diarrhea outpatients in China, with EAEC, EPEC and ETEC the most commonly identified subtypes. Epidemiological characteristics regarding the heterogeneities of DEC appeared different, in regions, age groups and seasons. Long-term surveillance programs should be strengthened to better understand the epidemiology of DEC, in China. Key words: Diarrhea; Sentinel surveillance; Diarrheagenic Escherichia coli; Seasonality