Frequency of reisolation of Staphylococcus aureus from multiple sequential milk samples.
Bacterial cultures were performed on multiple sequential composite samples of milk from 1,172 cows in 9 dairy herds. If the initial diagnosis of Staphylococcus aureus infection was based on the first positive culture, an average of 37.8% of subsequent cultures on the same cows were negative for S aureus. However, if the initial diagnosis of S aureus infection was confirmed by 2 or 2 of 3 sequential positive cultures and any conversions from S aureus positive to negative were confirmed by 2 or 2 of 3 sequential negative cultures, then only 17.0% converted to a negative diagnosis. Conversion of cows from S aureus culture-positive to -negative varied between herds; 8.1 to 69% for single cultures and 0.0 to greater than 40% for confirmed cultures.
Adams
D S
DS
Veterinary Medical Research and Development, Inc, Pullman, WA 99163.
Hancock
D
D
Fox
L
L
McDonald
J S
JS
D000818:Animals; D002417:Cattle; D005188:False Negative Reactions; D005260:Female; D008414:Mastitis, Bovine / Q000382:microbiology*; D008892:Milk / Q000382:microbiology*; D013203:Staphylococcal Infections / Q000382:microbiology / Q000662:veterinary*; D013211:Staphylococcus aureus / Q000302:isolation & purification*