![]() ![]() ![]() Stx can damage intestinal epithelial cells and kidneys, causing HC and HUS ( Smith et al., 2014). Shiga toxin (Stx) is the most critical virulence factor of STEC, consisting of two broad immunologically different types: Stx1 with three subtypes (Stx1a, Stx1c, and Stx1d) and Stx2 with seven subtypes (Stx2a to Stx2g). At present, detection methods and in depth studies are mainly focused on O157:H7 and the top six serogroups of STEC (O26, O45, O103, O111, O121, and O145) ( Conrad et al., 2014 Wasilenko et al., 2014), thus the public health significance of STEC of other serotypes is likely to be underestimated due to the high diversity of genotypes and phenotypes. In fact, non-O157 strains are responsible for a larger portion of STEC infections than O157 strains in the United States, Canada, Australia, Latin America, and Europe ( Karmali et al., 1985 Caprioli et al., 1997 Tozzi et al., 2003 Brooks et al., 2005). However, there is growing concern over the emergence of more than 200 non-O157 STEC serotypes associated with human illness, including the life threatening HUS ( Coombes et al., 2008). Strains of O157 serogroup have been considered to be most virulent, and STEC O157 strains have been extensively studied and shown to be involved in many cases and outbreaks of human disease ( Doorduyn et al., 2006 Friesema et al., 2007 Sigmundsdottir et al., 2007 Greenland et al., 2009). Shiga toxin-producing Escherichia coli (STEC) represents an emerging group of zoonotic pathogens causing diarrhea, hemorrhagic colitis (HC), and the life-threatening hemolytic uremic syndrome (HUS) in humans ( Smith et al., 2014). Based on the serotypes, virulence gene profiles and multi-locus sequence typing (MLST) analysis, the majority of these pika STECs may pose a low public health risk. This study provides the first report on STEC in plateau pikas and new information about STEC reservoirs in wildlife. Plateau pikas may play a role in the ongoing circulation of STEC in the Qinghai-Tibetan plateau. The 22 STEC isolates were divided into 16 pulsed-field gel electrophoresis patterns and 12 sequence types. Twenty antibiotics were active against all the STEC isolates all strains were resistant to penicillin G, and some to cephalothin or streptomycin. Adherence-associated genes iha and saa were, respectively, present in 72.73 and 68.18% of the STEC isolates. Fifteen, fourteen, and three STEC isolates harbored the virulence genes ehxA, subA, and astA, respectively. One stx 1 subtype ( stx 1a) and three stx 2 subtypes ( stx 2a, stx 2b, and stx 2d) were present in the STEC isolates. Thirteen different O serogroups and 14 serotypes were identified. Twenty-one samples (1.88%) yielded at least one STEC isolate in total, 22 STEC isolates were recovered. A total of 1116 pika samples, including 294 intestinal contents samples, 317 fecal samples, and 505 intestinal contents samples, were collected from May to August in the years 2012, 2013, and 2015, respectively. In this study we determined the prevalence and characteristics of the STEC in plateau pika ( Ochotona curzoniae) on the Qinghai-Tibetan Plateau, China. Ruminants are the natural reservoir of STEC. Shiga toxin-producing Escherichia coli (STEC) are an emerging group of zoonotic pathogens. 3Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Hangzhou, China.2Qinghai Institute for Endemic Disease Prevention and Control, Xining, China.1State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China.Xiangning Bai 1, Wang Zhang 1, Xinyuan Tang 2, Youquan Xin 2, Yanmei Xu 1, Hui Sun 1, Xuelian Luo 1, Ji Pu 1, Jianguo Xu 1,3, Yanwen Xiong 1,3* and Shan Lu 1* ![]()
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