Prevalence of Escherichia coli O157:H7 in the American bison (Bison bison).
Bison is becoming a popular meat source for consumers, but very little is known about the bison's status with respect to Escherichia coli O157:H7. We conducted a study to determine the prevalence and identify virulence genes and pulsed-field genetic types of E. coli O157:H7 in bison. Rectal contents and rectoanal mucosal swab (RAMS) samples were collected from a total of 342 bison at slaughter on seven different dates. Isolation of E. coli O157:H7 was by enrichment, immunomagnetic separation, and plating on selective medium, and identification was based on sorbitol fermentation reaction, indole production, and O157 agglutination test. An overall E. coli O157:H7 prevalence of 47.4% was observed. Fecal prevalence across sampling days ranged from 17 to 83%, with an average of 42.1%. The prevalence in the rectoanal mucosal region ranged from 2.2 to 50%, with an average of 19.9%. All E. coli O157:H7 isolates (n = 212) possessed eae, hlyA, fliC, and stx2 genes. The antiterminator Q gene, Q933, was present in 50.7% of fecal and 38% of RAMS isolates, and Q21 was present in 52.1% of fecal and 61.5% of RAMS isolates. The pulsed-field gel electrophoresis analysis of isolates revealed 11 types (> 95% Dice similarity) and 19 subtypes (100% Dice similarity). Two pulsed-field genetic types accounted for 76.4% of total isolates. Our study suggests that the prevalence of E. coli O157:H7 in rectal contents or on rectal mucosa of bison is variable, but relatively high overall and bison could serve as an important reservoir for human infection.
Department of Diagnostic Medicine and Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas 66506-5606, USA.
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Reinstein
J T
JT
Fox
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Shi
M J
MJ
Alam
T G
TG
Nagaraja
D000818:Animals; D015373:Bacterial Typing Techniques; D016164:Bison / Q000382:microbiology*; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D004197:Disease Reservoirs / Q000662:veterinary; D016521:Electrophoresis, Gel, Pulsed-Field; D019453:Escherichia coli O157 / Q000145:classification / Q000302:isolation & purification* / Q000472:pathogenicity; D005243:Feces / Q000382:microbiology; D005506:Food Contamination / Q000032:analysis*; D005516:Food Microbiology; D006801:Humans; D008460:Meat / Q000382:microbiology; D015995:Prevalence; D012007:Rectum / Q000382:microbiology; D014774:Virulence