The Persistent Isolation of Salmonella typhimurium from the Mammary Gland of a Dairy Cow.

The contamination of cheese by Salmonella typhimurium serotype 10 resulted in the bacteriological examination of raw milk from 327 farms on Prince Edward Island. A milk sample from a bulk tank from one farm was positive for this pathogen. The possible source was linked to the isolation of the strain from the milk from one quarter of one cow. Although the cow was asymptomatic for any clinical illness other than a chronic staphylococcal mastitis in two quarters, the animal continued to shed Salmonella in the milk during a 36 day period. Necropsy failed to reveal a source of the infection.