Objective: Reports of zoonotic transmission of methicillin-resistant Staphylococcus aureus (MRSA) between animals and humans suggests additional public health problem associated with this pathogen. The Marshfield Clinic/St. Josephs Hospital is a large medical complex with more than >300 physician providers, >5000 healthcare workers and a 500 bed facility. The medical complex is located in rural WI within dairy farming areas. This poses the potential for spread of healthcare associated MRSA to animals domesticated in farms that are located within the service area of the healthcare facility. We hypothesized that we would find MRSA isolates from farm animals that matched clones from the medical complex.
Methods: Two-hundred coagulase-positive Staphylococci isolates collected between 2006-2007 were characterized by molecular typing and for common virulence factor genes.
Result: S. aureus and MRSA were 15% and 4.5 % respectively of the coagulase-positive Staphylococci isolates. Three pulsed-field gel electrophoresis (PFGE) based clones (USA100, USA500, and unknown), were represented by five spa (t002, t045, t064, t242, t548) and three multilocus sequence types (MLST) (ST5, 8, 105). Two of the six SCCmec types (types II and IV) were observed. All MRSA strains were positive for clumping factors A and B, fibronectin binding protein A, and staphylococcal enterotoxin genes G and I but lacked lukSF-PV genes.
Conclusion: Two (ST5 and ST8) of the five major clonal complexes were observed. Both USA100 and USA500 two of the six major MRSA clones known to be endemic in the medical complex suggesting possible human to animal transmission.