title: Efficacy of different Lysigin formulations in the prevention of Staphylococcus aureus intramammary infection in dairy heifers.
abstract: The objective was to compare the efficacy of two experimental Staphylococcus aureus mastitis bacterins and a currently marketed five-isolate-based Staph. aureus bacterin (Lysigin, Boehringer Ingelheim Vetmedica, Inc.) with unvaccinated controls. Forty-seven Holstein-Friesian heifers were randomly assigned to one of four groups such that Group 1 (n=11) received a three-isolate experimental bacterin, Group 2 (n=11) received a five-isolate experimental bacterin, Group 3 (n=14) received Lysigin, and Group 4 (n=11) served as unvaccinated controls. Vaccinations were administered twice 28 d apart in late gestation. All groups were challenged with a heterologous strain of Staph. aureus (ATCC 29740) on days 6, 7, and 8 of lactation. Mastitis score, somatic cell count (SCC), milk culture yield, and total daily milk yield data were collected before and after challenge. All 47 cattle developed a Staph. aureus IMI post-challenge with three animals in Group 1 and one animal in Group 3 clearing their Staph. aureus IMI by the end of the study. However, there was no evidence of a difference between vaccinates and control with regard to Staph. aureus clearance rates post-challenge (P> or =0.214). Cattle vaccinated with Lysigin had a lower mean duration of clinical mastitis and lower total mastitis score post-challenge than controls (P=0.045 and P=0.046, respectively). Overall, there was no evidence that any of the vaccinated groups had a lower mean SCC than control (P> or =0.148) for the tested study days. Likewise there was no evidence that vaccinates had greater milk yield than controls post-challenge (P=0.617). Hence, there was no evidence that the vaccines reliably prevented Staph. aureus IMI, but Lysigin showed benefit in reducing the clinical severity and duration of clinical disease post-challenge. Neither of the experimental bacterins appeared to perform better than Lysigin.
authors.affiliation: Department of Veterinary Medicine and Surgery, University of Missouri, Columbia, Missouri, USA. middletonjr@missouri.edu
authors.forename: John R
authors.initials: JR
authors.lastname: Middleton
authors.forename: Jianneng
authors.initials: J
authors.lastname: Ma
authors.forename: Carol L
authors.initials: CL
authors.lastname: Rinehart
authors.forename: Veronica N
authors.initials: VN
authors.lastname: Taylor
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Luby
authors.forename: Barry J
authors.initials: BJ
authors.lastname: Steevens
mesh_terms: D000818:Animals; D001428:Bacterial Vaccines / Q000276:immunology*; D002417:Cattle; D002452:Cell Count / Q000662:veterinary; D005260:Female; D008414:Mastitis, Bovine / Q000453:epidemiology / Q000517:prevention & control*; D008892:Milk / Q000166:cytology / Q000382:microbiology; D015995:Prevalence; D011897:Random Allocation; D012720:Severity of Illness Index; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000517:prevention & control / Q000662:veterinary*; D013211:Staphylococcus aureus; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D001428:Bacterial Vaccines