Efficacy of vaccination and antimicrobial treatment to eliminate chronic intramammary Staphylococcus aureus infections in dairy cattle.
OBJECTIVE
To determine whether a combination of vaccination and extended intramammary antimicrobial treatment would eliminate chronic intramammary Staphylococcus aureus infections in lactating dairy cows.


METHODS
Randomized controlled clinical trial.


METHODS
50 dairy cows with chronic mastitis caused by S aureus.


METHODS
Cows were identified and paired within herd on the basis of days in milk, lactation number, milk production, and numbers of quarters infected. Treated cows (n=20) received 3 doses of a polyvalent S aureus bacterin on days 1, 15, and 21 of the study along with intramammary administration of pirlimycin in all 4 quarters once daily for 5 treatments (days 16 to 20). Control cows (n=23) received no treatment. Follow-up samples for bacteriologic culture were collected for at least 3 months after treatment to determine treatment success rates.


RESULTS
Significantly more S aureus infections were eliminated from treated cows (8/20 [40%]), compared with control cows (2/23 [9%]). The proportion of infected quarters that yielded negative results throughout the follow-up period was also significantly higher in treated cows (13/28 [46%]) than in control cows (2/41 [5%]).


CONCLUSIONS
Results indicate that a combination of vaccination and antimicrobial treatment can be successful in eliminating some cases of chronic intramammary S aureus infections in dairy cattle. However, it is important to consider extended treatment protocols carefully because many cows are likely to remain infected with S aureus despite treatment and vaccination.
Smith
Geof W
GW
Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, Raleigh, NC 27606, USA.
Lyman
Roberta L
RL
Anderson
Kevin L
KL
D000818:Animals; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D001428:Bacterial Vaccines / Q000008:administration & dosage; D002417:Cattle; D002908:Chronic Disease; D002981:Clindamycin / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000627:therapeutic use; D003612:Dairying / Q000379:methods; D005260:Female; D008414:Mastitis, Bovine / Q000188:drug therapy* / Q000382:microbiology / Q000517:prevention & control*; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000382:microbiology / Q000517:prevention & control / Q000662:veterinary*; D013211:Staphylococcus aureus / Q000276:immunology*; D016896:Treatment Outcome; D014611:Vaccination / Q000662:veterinary*
D000900:Anti-Bacterial Agents; D001428:Bacterial Vaccines; D002981:Clindamycin; C034093:pirlimycin