spa typing of methicillin-resistant Staphylococcus aureus isolated from domestic animals and veterinary staff in the UK and Ireland

Objectives: Region X of the protein A gene (spa) was sequenced from methicillin-resistant Staphylococcus aureus (MRSA) isolates originating from animals, humans and the environment at veterinary hospitals in the UK and Ireland. MRSA transmission between animals and veterinary staff was assessed on the basis of spa typing, PFGE and epidemiological data. Methods: MRSA isolates from dogs (n = 27), horses (n = 9), cats (n = 6), staff (n = 22) and environmental surfaces (n = 3) were analysed by PFGE and spa typing. Known contacts between human and animal MRSA carriers were ascertained from the veterinary hospitals. Results: All feline, most canine (96%) and human (82%) isolates showed PFGE profiles that were either indistinguishable (subtype A1) or closely related (subtypes A2–A10) to that of the epidemic clone EMRSA-15 (CC22), whereas most equine isolates (88%) were related to CC8 (types C, D, E and G). spa polymorphism enabled discrimination among MRSA strains assigned to the same PFGE type. Fifteen spa types clustering into two distinct groups were detected, with t032 being the most prevalent (48%). The spa and PFGE types of MRSA isolated from seven staff members were the same as those of strains isolated from infected animals attended by the staff. Conclusions: Irrespective of geographical origin, MRSA isolated from equine and small animal hospitals generally clustered into two distinct clonal complexes, CC8 and CC22, respectively. The combined use of spa and PFGE typing allowed better discrimination than each method used individually, and provided useful information on MRSA transmission between animal and human individuals.