The role of teat skin contamination in the epidemiology ofStaphylococcus aureusintramammary infections

Abstract

Knowledge of the epidemiological pattern and the potential sources of infections is important to controlStaphylococcus aureusin dairy herds. This paper reports the results of a study applying both pulse field gel electrophoresis (PGFE) and the assessment of a selected number of virulence genes to investigate the role of teat skin onStaph. aureustransmission among cows and on the contamination of milk. Overall 61 isolates were considered, 23 from teat skin, 33 from milk samples and 5 from curd samples. Teat swabs were taken in five herds, but in only three of them couldStaph. aureusbe isolated. Curd was sampled in three herds, butStaph. aureuscould be isolated in only two herds. The distribution of isolates among herds confirmed the presence of herd-specificStaph. aureusstrain in most of the herds. The same pattern was observed in teat skin samples, in quarter milk samples, and in the curd samples. Our findings are consistent with other studies showing the role of teat skin as a potential reservoir. Moreover,Staph. aureuswas isolated from teat skin of confirmedStaph. aureus-negative cows that were segregated from infected ones. Our findings also suggest that some strains have higher chances to survive on teat skin and therefore to increase the risk for contamination of milk and milk products due to the persistence of intramammary infections.