New Strain of E. coli Found

By: John Maday

Cattle feeders and veterinarians should keep an eye out for E. coli O165:H25, an enterohemorrhagic strain that can cause disease in cattle and potentially poses a food-safety hazard for humans.

The O165:H25 strain typically is found in young calves, and generally does not cause clinical disease in cattle. However, during the recent Academy of Veterinary Consultants conference, Veterinarian Russ Rice, from Broken Bow, Nebraska, outlined a case of the pathogen apparently causing enteric disease in heifers in a Nebraska feedlot. In February, Rice says, the feedlot crew began pulling some heifers from the pen of 170 head for respiratory disease treatment. He noted that some bloody stools were present in the pen, and he treated the cattle for coccidiosis. Bloody stools persisted though and one animal died.

Upon necropsy, gross lesions included inflamed cecum and large bowel. Rice then submitted fresh and fixed specimens to the University of Nebraska diagnostic laboratory. The laboratory found signs of attaching and effacing E. coli and diagnosed the O165:H25 enterohemorrhagic strain.

A week after adding bovamine to the ration, reducing wet distillers’ grains and increasing roughage, fecal samples from the pen were negative for E. coli 0165:H25. Sampling in the adjacent pen revealed the presence of coccidia, and Rice suspects coccidiosis initially infected the heifers later diagnosed with E. coli O165:H25. He also suggests that cases of enterohemorrhagic E. coli could be mistaken for coccidiosis, salmonella, BVD or other diseases without laboratory diagnosis.

The 0165:H25 serotype, Rice adds, is similar to E. coli O157:H7, and could be an emerging food-borne pathogen in cattle and beef. He suggests veterinarians include enterohemorrhagic E. coli in their list of differential diagnoses when they see enteric disease in feedlot cattle.

The case study was published in the Journal of Molecular Microbiology in November 2015.