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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Food Safety and Enteric Pathogens Research » Research » Publications at this Location » Publication #334503

Research Project: Characterization of Colonization of Shiga Toxin-producing Escherichia coli (STEC) in Cattle and Strategies for Effective Preharvest Control

Location: Food Safety and Enteric Pathogens Research

Title: Complete genome sequences of curli-negative and curli-positive isolates of foodborne Escherichia coli O157:H7 strain 86-24

item Sharma, Vijay
item Bayles, Darrell
item Alt, David
item Looft, Torey

Submitted to: Genome Announcements
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/24/2016
Publication Date: 12/15/2016
Citation: Sharma, V.K., Bayles, D.O., Alt, D.P., Looft, T.P. 2016. Complete genome sequences of curli-negative and curli-positive isolates of foodborne Escherichia coli O157:H7 strain 86-24. Genome Announcements. 4(6):e01323-16. doi: 10.1128/genomeA.01323-16.

Interpretive Summary: Escherichia coli O157:H7 (O157) causes sporadic outbreaks of diarrheal illnesses in humans. However, these illnesses in children and the elderly carry the risk of leading to kidney failure, neurological complications, and even death. Humans become infected with O157 by consuming undercooked ground beef, vegetables, and water contaminated with O157 bacteria. The major sources for the contamination of these foods and water are cattle feces or manure containing O157. Since O157 bacteria preferentially colonize the digestive tract of cattle, colonized animals shed these bacteria in their feces, which pose major risk to the contamination of cattle carcasses that are processed into ground beef and other meat cuts. These feces are also a risk factor for the contamination of drinking water as well as run-off water from cattle production facilities posing the down-stream risk to the contamination of vegetables and other produce. The genetic mechanisms employed by O157 bacteria to colonize and persist in the digestive tract of cattle are not fully understood. Newer technologies to unravel the entire genetic make-up of bacterial populations are becoming increasingly valuable to identify genetic features of bacteria facilitating bacterial infection or colonization of a susceptible host animal. By using one of these technologies we determined the complete genetic make-up of two O157 bacterial strains. Fine-tune analysis of the genetic make-up, allowed identification of some of the genetic features that could potentially enhance survival of O157 in cattle and the environment outside the cattle. The practical field applications of having detailed genetic fingerprints would be to use these as reference tools to identify how these genetic fingerprints and the genetic information produced by these fingerprints change during the course of colonization of O157 in cattle or during survival in the environment, such as feces and manure. In addition, these fingerprints would be important in identifying genetic features that could be used as O157-specific biomarkers and as targets in vaccine candidates.

Technical Abstract: Escherichia coli O157:H7 strain 86-24 does not produce curli fimbriae, but can give rise to curli-positive isolates at a variable frequency. Here, we report the whole-genome sequences of curli-negative and curli-positive isolates of strain 86-24.