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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 #140722
Title: ESCHERICHIA COLI O157:H7 IN THE GALLBLADDERS OF EXPERIMENTALLY INFECTED CALVES

Author
item Stoffregen, William
item POHLENZ, J - HANNOVER VET SCHOOL
item Nystrom, Evelyn

Submitted to: Journal of Veterinary Diagnostic Investigation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/17/2003
Publication Date: 1/20/2004
Citation: STOFFREGEN, W.C., POHLENZ, J.F., NYSTROM, E.A. ESCHERICHIA COLI O157:H7 IN THE GALLBLADDERS OF EXPERIMENTALLY INFECTED CALVES. JOURNAL OF VETERINARY DIAGNOSTIC INVESTIGATION. 2004. V. 16. P. 79-83.

Interpretive Summary: Cattle are an important source of Shiga toxin-producing Escherichia coli (STEC) O157:H7, foodborne pathogens that cause severe diarrhea and sometimes kidney failure and death in humans. One way to reduce the risk of STEC O157:H7 infections in humans is to reduce the level of STEC O157:H7 in cattle. When, where, or how cattle become infected is not known. Weaned calves and adult cattle remain healthy after infection with STEC O157:H7. Naturally- and experimentally-infected cattle can shed O157:H7 in their feces for a long time. In this study, weaned calves were treated daily with high doses of dexamethasone from 3 days before to 1 day after they were inoculated with STEC O157:H7 bacteria. At 4 days after inoculation, STEC O157:H7 bacteria were recovered from the intestines or feces of 13 of 13 calves and from the gall bladders of 5 of 13 calves. Attaching and effacing lesions were found in the large intestines of 12 of 13 calves and in the gall bladders of 5 of 13 calves. The discovery of STEC in the gall bladders of these calves identifies the bovine gall bladder as a possible niche for STEC infection in cattle, and as a potential source of STEC contamination of beef products. Including gall bladders in the samples cultured for STEC may help identify STEC-infected cattle at slaughter and thus help reduce STEC contamination of beef products and the incidence of STEC disease in humans.

Technical Abstract: Fifteen weaned calves (age 89-141 days) were treated with dexamethasone (0.25 mg/kg, IV) for three days prior, the day of inoculation, and the day after inoculation with 1010 CFU of either Escherichia coli O157:H7 (strain 86-24 that produces Shiga toxin 2 and intimin; n = 13) or nonpathogenic E. coli (strain 123 that does not produce Shiga toxin or intimin; n = 2). All calves were necropsied 4 days after inoculation. Histologic lesions of attaching and effacing bacteria were observed in the large intestine (12/13) and in the gall bladder mucosa (5/13) of calves inoculated with E. coli 86-24. Cholecystitis was present in 12 of 13 calves that received E. coli 86-24. Inoculum bacteria were recovered from the distal colons or feces (13/13) and gall bladders (3/4) of calves inoculated with 86-24.