Methicillin-resistant Staphylococcus aureus in a veterinary orthopaedic referral hospital: staff nasal colonisation and incidence of clinical cases.

Objectives: To evaluate staff nasal colonisation with meticillin-resistant Staphylococcus aureus in a veterinary orthopaedic referral hospital, and its effect on the occurrence of meticillin-resistant Staphylococcus aureus-associated postoperative wound complications in orthopaedic and spinal surgical patients. Methods: Nasal bacterial swabs were collected from veterinary staff and environmental surfaces swabbed at six monthly intervals for meticillin-resistant Staphylococcus aureus monitoring over an 18 month period. The incidence of meticillin-resistant Staphylococcus aureus-associated postoperative wound complications of two veterinary orthopaedic surgeons was reviewed for a period when one was positive for nasal meticillin-resistant Staphylococcus aureus. Results: Meticillin-resistant Staphylococcus aureus was isolated from a maximum of two out of 10 staff on each occasion. The persistently infected clinician was primary surgeon in 180 cases, of which four developed meticillin-resistant Staphylococcus aureus-associated wound complications. None of 141 operations led by the other surgeon developed meticillin-resistant Staphylococcus aureus-associated complications. This difference is not statistically significant (P=0.0974). The 95 per cent confidence interval for this odds ratio was 0.83 to 44.0. Meticillin-resistant Staphylococcus aureus resistance patterns of the human nasal isolates and three of four wound-associated isolates were similar. Clinical Significance: Veterinary workers are at increased risk for meticillin-resistant Staphylococcus aureus colonisation, so it is likely that many veterinary patients are treated by meticillin-resistant Staphylococcus aureus-positive staff. Nasal colonisation of veterinary surgeons with meticillin-resistant Staphylococcus aureus appears to present only a small risk to their patients when appropriate infection control procedures are followed.