A reservoir for methicillin-resistant Staphylococcus aureus in the Auckland community?

To determine if there is a difference in methicillin-resistant Staphylococcus aureus (MRSA) colonisation rates between patients over the age of 60 years admitted to Auckland Hospital from either residential care facilities (RCF) or the community.

A prospective cohort study. The following information was collected: patient demographics; admission in the last 12 months; presence of risk factors for MRSA colonisation; any history of MRSA colonisation. Swabs from the nose, perineum and any infected wounds or skin lesions were collected. Urine was cultured if the patient had a urinary catheter in situ.

19 (9%) patients of 213 from RCF, and 6 (3%) patients of 201 from the community were positive for MRSA (p = 0.02). Patients admitted to hospital in the previous 12 months were three times more likely to be colonised with MRSA than others (p = 0.01). Excluding those patients already known to be MRSA positive, patients admitted from RCF were six times more likely to be newly found to be MRSA positive. Twenty four of the 25 MRSA isolates were EMRSA-15.

Patients from RCF are statistically more likely to be colonised with MRSA compared with patients of similar age admitted from the community. Identification of such high-risk carriers allows targeted infection control activity to control MRSA within hospitals.