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
Tel: +86- 451-51997177
Fax: +86- 451-51997166
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