Characterization of Shiga-Toxin Producing Escherichia coli Isolated From Cattle and Sheep in Xinjiang Province, China, Using Whole-Genome Sequencing
Running title: Analysis of Shiga-Toxin Producing Escherichia coli
Yingyu Liu1#, Huoming Li2#, Xuhua Chen2,3, Panpan Tong1, Yan Zhang1, Mingyue Zhu1, Zhanqiang Su1, Gang Yao1, Ganwu Li2,3*, Wentong Cai2*
1 College of Veterinary Medicine, Xinjiang Agricultural University, Urumqi, China
2 Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
3 Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA
# These authors contributed equally to this study.
* Corresponding author:
Wentong Cai, PhD. caiwentong@caas.cn
Ganwu Li, PhD. liganwu@caas.cn
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Summary: Shiga toxin-producing Escherichia coli (STEC) is an important foodborne pathogen capable of causing severe gastrointestinal diseases in humans. Cattle and sheep are the natural reservoir hosts of STEC strains. Previously, we isolated 56 STEC strains from anal and carcass swab samples of cattle and sheep in farms and slaughterhouses. In this study, we performed whole-genome sequencing of these isolates and determined their serotypes, virulence profiles, sequence types (STs), and genetic relationships. Our results showed that the 56 isolates belong to 20 different STs, 29 O:H serotypes, and 8stx subtype combinations. The highly prevalent serotypes were O8:H25 and O87:H16 for bovine and ovine isolates, respectively. Five serotypes of cattle or sheep isolates are novel. The majority (63%) of cattle isolates contain stx 1+stx 2, subtyped intostx 1a, stx 2a, and stx 2c. In contrast, most of the sheep isolates contain stx 1 only, primarily subtyped intostx 1a and stx 1c. None of the isolates testedeae -positive, but virulence factors such as ehxA andespP were present with variable prevalence rates. The prevalence of saa (19.6%) and espP (12.5%) in cattle isolates is much higher than that in sheep isolates, whereas that of subA(34%), katP (14.3%), and ireA (28.6%) in sheep isolates is considerably higher than that in cattle isolates. Core-genome SNP analysis revealed that the majority of isolates could be clustered based on their serotypes or STs, whereas some clustering is associated with more than one ST or serotype. Seven-gene Multilocus Sequence Typing (MLST) indicated that nine sheep isolates and four cattle isolates were related to a few E. coli isolates associated with human HUS, suggesting their potential in causing severe human infections. Collectively, we described the characteristics of cattle and sheep STEC isolates from Xinjiang, China, which may be utilized in comparative studies of other geographic regions and sources of isolation and for surveillance.
Keyword: Shiga-toxin producing Escherichia coli ; Whole-genome sequencing; Cattle and sheep; Xinjiang province