Epidemiology, virulence factors and antibiotic resistance inStaphylococcus aureusstrains isolated in small ruminant dairy chain

The aim of the present thesis was to conduct an extensive characterization ofS. aureusisolated from small ruminant milk and dairy products.S. aureusis considered a major public health concern because of its ability to give disease in human, after consumption of contaminated foods with enterotoxins. This pathogen can aquire resistance against several antibiotics used in human and veterinary practices. Farms and cheese-making plants can serve as a reservoir ofS. aureusand are involved in the spread of the microorganism into environment. Concern exists on the possible acquisition of antibiotic resistance by human strains, as consequence of exchange of mobile genetic elements with strains of animal origin. The extent and impact of these strains on human health was also assessed.In chapters 3, 4, and 5 are presented results on prevalence, virulence factors and antibiotic resitance ofS. aureusstrains isolated from goats with subclinical mastitis and from bulk tank milk. In chapters 6, 7 and 8 are reported results onS. aureusstrains isolated from raw sheep’s milk cheese. Prevalence, virulence daterminants and antibiotic resistance have been assessed. Additional informations have been provided on the genetic variability of the strains and their relationship with the host.