Prevalence and Characterization of Staphylococcus aureus, Including Methicillin-Resistant Staphylococcus aureus, Isolated from Bulk Tank Milk from Minnesota Dairy Farms

摘要: Staphylococcus aureus is a common causative agent of bovine mastitis in dairy herds. The emergence methicillin-resistant (MRSA) hospitals as well the community significant and costly public health concern. S. aureus-related reason for therapeutic and/or prophylactic use antibiotics on farms. In this study, herd prevalence aureus, including MRSA, was estimated from bulk tank milk (BTM) Minnesota A total 150 pooled BTM samples 50 farms, collected over 3 seasons (spring, summer, fall 2009), were assessed. Herd methicillin-susceptible (MSSA) 84%, while MRSA 4%. 93 MSSA isolates 2 recovered samples. Antibiotic susceptibility testing showed pansusceptibility 54 isolates, resistance to single antibiotic class 21 two classes 13 ≥3 thus multidrug 5 isolates. displayed β-lactams, cephalosporins, lincosamides multiresistant. Staphylococcal protein gene (spa) typing identified spa types t529 t034 most frequently among t121 observed Seven produced staphylococcal enterotoxins B, C, D, E overnight culture. further genotyped using multilocus sequence (MLST) pulsed-field gel electrophoresis (PFGE). Of one had composite genotype profile MLST ST 5-PFGE USA100-unknown type, which has been reported hospital-associated second isolate carried 8-PFGE USA300-spa type genotype, commonly community-associated These results suggest that genotypes associated with can be isolated at very low rates.