Identification of staphylococci and Corynebacterium spp. isolated from milk and cow teat skin samples using PCR and their association with new IMI, hyperkeratosis, and teat condition

Mastitis adversely affects the profitability of the dairy industry worldwide. Although it has been shown that multiple factors are related to mastitis, poor milking hygiene would be able to increase the risk of mastitis. Disinfection of the teat skin after milking helps reduce the spread of mastitis pathogens. The objective of the present study was to use PCR as a diagnostic method for identifying staphylococci and Corynebacterium spp. isolates recovered from milk or teat skin surface and to evaluate bacterial populations on teat ends of cows and examine the correlation between the number of bacteria on teat ends and the incidence of a new IMI, hyperkeratosis score, and teat skin condition. A total of 212 Holstein dairy cows were randomly recruited into the study. Milk samples from the right front quarters were taken twice on Days 0 and 14; however, teat skin swabs from the right front quarters were collected on Day 0. The dryness of teat skin and hyperkeratosis was scored on Day 0. All staphylococci and Corynebacterium bovis isolates recovered from milk or teat skin swab cultures were confirmed using the PCR method at a genus and species level. There was a significant relationship between CNS count on the teat skin surface on Day 0 and the isolation of CNS from milk samples on Day 14. It was concluded that increasing the population of CNS bacteria on the surface of teat skin would increase the probability of the incidence of new IMI caused by CNS.