Prevalence of coagulase-positive staphylococci, other than Staphylococcus aureus, in bovine mastitis.
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).


METHODS
Prevalence of CPS was determined for primiparous cows (point prevalence and prevalence at first parturition) and multiparous cows (point prevalence) of 2 herd groups: < 6% CPS IMI prevalence = low prevalence (LP); > 10% CPS IMI prevalence = high prevalence (HP).


METHODS
For prevalence, cows of 22 dairy herds. For TC, 1,038 CPS strains isolated from cow milk.


METHODS
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 > or = 97% sensitive, < or = 33% specific, and had a predictive value positive range of 60 to 97% for S aureus isolates.


CONCLUSIONS
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.
Roberson
J R
JR
Department of Large Animal Clinical Sciences, Virginia Technological Institute and State University, Blacksburg, 24061-0442, USA.
Fox
L K
LK
Hancock
D D
DD
Gay
J M
JM
Besser
T E
TE
D000818:Animals; D001431:Bacteriological Techniques; D002417:Cattle; D003030:Coagulase; D005260:Female; D008414:Mastitis, Bovine / Q000382:microbiology*; D008892:Milk / Q000382:microbiology; D015995:Prevalence; D012680:Sensitivity and Specificity; D013045:Species Specificity; D013203:Staphylococcal Infections / Q000145:classification / Q000453:epidemiology / Q000662:veterinary*; D013210:Staphylococcus / Q000145:classification* / Q000302:isolation & purification*; D013211:Staphylococcus aureus / Q000145:classification / Q000302:isolation & purification
D003030:Coagulase