RESUMO
The purpose of this project was to evaluate the use of 2 selective/differential culture media for detecting Staphylococcus aureus in bulk tank milk. One medium was Baird-Parker agar base supplemented with egg york tellurite emulsion and acriflavine. The other medium was Baird-Parker agar base supplemented with rabbit plasma/bovine fibrinogen and acriflavine. An increased inoculum of bulk tank milk (0.3 mL) was used to enhance the detection of S. aureus in samples containing low numbers of organisms. The sensitivity and specificity for detecting S. aureus in bulk tank milk were 94.8% and 100%, respectively, using Baird-Parker agar base supplemented with egg yolk tellurite emulsion and acriflavine, and 89.7% and 100%, respectively, using Baird-Parker agar base supplemented with rabbit plasma/bovine fibrinogen and acriflavine. Both media are practical for detecting S. aureus in bulk tank milk and monitoring its spread in lactating dairy herds in Alberta.
Assuntos
Microbiologia de Alimentos , Leite/microbiologia , Staphylococcus aureus/isolamento & purificação , Alberta/epidemiologia , Animais , Bovinos , Doenças dos Bovinos/diagnóstico , Doenças dos Bovinos/epidemiologia , Meios de Cultura , Estudos de Avaliação como Assunto , Reações Falso-Negativas , Feminino , Mastite Bovina/diagnóstico , Mastite Bovina/epidemiologia , Valor Preditivo dos Testes , Prevalência , Sensibilidade e Especificidade , Infecções Estafilocócicas/diagnóstico , Infecções Estafilocócicas/epidemiologia , Infecções Estafilocócicas/veterináriaRESUMO
A case-control study was undertaken during the summer of 1989 in central Alberta dairy herds to identify independent predictors of nocardial mastitis. Thirty-seven herds with nocardial mastitis were matched with control herds based on herd size, milk production, and enrolment in Alberta Dairy Herd Improvement Services. Control herds were considered free of nocardial mastitis based on negative cultures of four weekly bulk tank milk samples and one composite milk sample collected during the same period from each lactating cow in the herd. A detailed questionnaire on herd management was completed during farm visits. The use of blanket dry cow therapy was not found to be a risk factor for nocardial mastitis. Dry cow therapy with intramammary products containing neomycin and the use of multidose vials of dry cow medications were the only predisposing factors identified as being significantly associated with nocardial mastitis in central Alberta dairy herds. Use of neomycin as a dry cow therapy increased the odds of nocardial mastitis occurring in these dairy herds by 169 times.