Prevalence of coagulase-positive staphylococci, other than Staphylococcus aureus, in bovine mastitis
Roberson, J.R.; Fox, L.K.; Hancock, D.D.; Gay, J.M.; Besser, T.E.
American Journal of Veterinary Research 57(1): 54-58
1996
ISSN/ISBN: 0002-9645 PMID: 8720238 Document Number: 466166
Objective-To determine prevalence and relevance of coagulase-positive Staphylococcus hyicus and S intermedius intramammary infections (IMI) in dairy cows and determine the ability of the 4-hour tube coagulase (TC) test to differentiate the coagulase-positive staphylococci (CPS). Design-Prevalence of CPS was determined for primiparous cows (point prevalence and prevalence at first parturition) and multiparous cows (point prevalence) of 2 herd groups: lt 6% CPS IMI prevalence = low prevalence (LP); gt 10% CPS IMI prevalence = high prevalence (HP). Sample population For prevalence, cows of 22 dairy herds. For TC, 1,038 CPS strains isolated from cow milk. Procedure-Speciation of CPS from aseptically collected composite milk samples was performed. Coagulase-positive isolates from 4 cow groups were tested for their ability to coagulate rabbit plasma by 4 hours: LP and HP primiparous cows at parturition, and LP and HP cows any time after first parturition. Results-Of 487 CPS in the prevalence study, 82.1% were S aureus, 17.7% were coagulase-positive S hyicus, and 0.2% were S intermedius. Of all CPS IMI in LP herds 34% were coagulase-positive S hyicus; of all CPS IMI in HP herds, 9% were coagulase-positive S hyicus. Coagulase-positive S hyicus appeared to persist to the end of lactation in 4 cows (mean linear somatic cell count = 3.7). The TC test was gtoreq 97% sensitive, ltoreq 33% specific, and had a predictive value positive range of 60 to 97% for S aureus isolates. Conclusion-Coagulase-positive S hyicus appears capable of inducing chronic, low-grade IMI. Staphylococcus intermedius does not appear to be an important mastitis pathogen. The TC test is not valid to use as the sole method to differentiate CPS species.