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P2-174 Comparative Genome Analysis Reveals a Hyper-virulent Escherichia coli O157:H7 Strain Isolated from a Super-shedder

Tuesday, August 2, 2016
America's Center - St. Louis
Lin Teng, University of Florida, Gainesville, FL
Min Young Kang, University of Florida, Gainesville, FL
Sarah Markland, University of Florida, Gainesville, FL
Choonghee Lee, University of Florida, Gainesville, FL
Raies Mir, University of Florida, Gainesville, FL
Zhengxin Ma, University of Florida, Gainesville, FL
Dongjin Park, Keimyung University, Daegu, Korea, The Republic of
Kwangcheol Jeong, University of Florida, Gainesville, FL
Introduction: Shiga toxin-producing Escherichia coli (STEC) O157:H7 is a foodborne pathogen that threatens public health on a global scale. STEC O157 predominantly colonizes the terminal recto-anal junction (RAJ) of cattle, which is the major asymptomatic reservoir of this pathogen. Cattle shedding O157 ≥ 104 CFU/g of feces are known as super-shedders and are responsible for within-farm and between-farm transmission of STEC O157. 

Purpose: The purpose of this study was to perform genetic characterization of KCJ1266, a strain isolated from a super-shedder steer from a farm in North Florida. 

Methods: PacBio sequencing was employed for whole genome sequencing (WGS) to characterize the genomic features of KCJ1266. A comparative genome analysis of KCJ1266 with reference genomes including SS17 (strain isolated from a super-shedder), EC4115 (strain related to spinach outbreak) and EDL933 (strain related to hamburger outbreak) was conducted.

Results: WGS of KCJ1266 revealed that it has a genome of 5,478,683 bp encoding 5,545 open reading frames and a plasmid, pO157, of 95,910 bp. In silico analysis revealed that KCJ1266 belongs to E. coli Lineage I/ II and clade 8, which are related to other disease-causing isolates. In addition, Mauve alignment showed that KCJ1266 shares a similar genomic architecture with SS17 and EC4115. Comparative analyses also revealed that KCJ1266 has the same virulence and similar functional genes as SS17 and EC4115. Phylogenetic analysis showed that KCJ1266, SS17 and EC4115 clustered in the same group. Taken together, these results reveal that super-shedding STEC strain KCJ1266 is a hyper-virulent strain similar to that of SS17 and EC4115. 

Significance: This is one of the first studies which utilizes PacBio WGS to characterize a hyper-virulent STEC O157 strain isolated from super-shedding cattle. KCJ1266 can potentially be used as a reference strain for future studies regarding the phenomenon of super-shedding.

Back to: Poster Session 2 – Low-water Activity, Laboratory and Detection Methods, Epidemiology, Produce, Pre-harvest, Dairy and Beverages, Food Defense, General Microbiology
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