Significance of methicillin-resistant Staphylococcus aureus (MRSA) survey in a university teaching hospital

We experienced a methicillin-resistant Staphylococcus aureus (MRSA) outbreak in two wards at our medical school teaching hospital during the period of July-September 1997. To determine whether these MRSA clinical isolates were associated with environmental factors, we conducted two sequential MRSA surveys of the hospital staff and surroundings in wards with outbreaks (wards 1 and 2) and in one ward without an outbreak (ward 3) in April 1998 (ward 1 only) and in March 1999 (wards 1, 2, and 3). In the two sequential surveys, MRSA strains were detected mainly from white coats. MRSA strains isolated from fingers in the first survey were decreased in the second survey. The pulsed-field gel electrophoresis (PFGE) patterns of the strains isolated in the two surveys were classified into five types (A-E). Type D, including the outbreak pattern of the MRSA in ward 1 in 1997, was reduced between the first and second surveys by managing microbiological hygiene, suggesting that the outbreak was controlled in ward 1. On the other hand, the strains isolated in the second survey in ward 2 were mainly type E, which was also common among clinical isolates from ward 2 during the latter half of 1998 to 1999. This suggested a high probability of cross-infection between the patients and the hospital staff in the ward. Our observations suggest that doctors and nurses should be cautious that their coats might be contaminated with the prevailing strains of MRSA. We also concluded that the surveys were very useful for the successful management of MRSA infections.