Epidemiological study of methicillin-resistant Staphylococcus aureus at Fukuoka University Hospital

To clarify what types of methicillin-resistant Staphylococcus aureus (MRSA) strains were easily transmitted and colonized in the inpatients of the emergency center and the neonatal intensive-care unit (NICU) at Fukuoka University Hospital, 70 MRSA isolates obtained from February to November 1995 (the first survey) and from November 1996 to March 1997 (the second survey) were investigated biologically and genetically. Pulsed-field gel electrophoresis (PFGE) showed 12 types (PFGE types A-L) of DNA patterns for the MRSA isolates. At the emergency center, the PFGE types A and B strains were isolated from 40.9% and 27.2% of the MRSA-excreting patients in the first survey, respectively, while type E was isolated from 66.7% in the second survey. At the NICU, type A and J strains were isolated from 33.3% and 55.6% of the MRSA-excreting patients in the first survey, while the types A and B were isolated from 25% and 50%, respectively, in the second survey. Type A-D strains were isolated in both wards, while other epidemic types strains were isolated in only one ward. These results suggest that the type A and B strains have been colonized in the two wards for a long time and these strains might spread and colonize easily in the patients. Type C and D strains have also been colonized, but only in a small population over the two wards.