Molecular epidemiology of methicillin‐resistant Staphylococcus aureus in a pediatric ward

Background: Nosocomial infections caused by methicillin-resistant Staphylococcus aureus (MRSA) are one of the most serious problems in pediatric wards. Epidemiological analysis of strains isolated in the ward is essential for infection control. There have been few reports in which a molecular epidemiological study of MRSA was performed in pediatric wards. Methods: Fifty-six MRSA strains isolated in the pediatric ward of Asahikawa Medical College Hospital between 1995 and 1997 were studied. Fifty-two and four isolates were obtained from 27 patients and from two medical staff members, respectively. Forty-one isolates were regarded as colonizing strains and 15 were causes of infections. Genotypes of the isolates were investigated by pulsed-field gel electrophoresis (PFGE). Results: The PFGE patterns of 56 isolates were classified into nine types: type A, its subtypes, A1 and A2, and types B through to G. Seventeen isolates were type A, 32 were type A1, and one of each type of A2 and B through to G were identified. Fifty of 56 isolates, which were isolated from 24 of 29 cases, belonged to type A or its subtypes. Conclusions: The predominant strain of MRSA isolates in the pediatric ward was a certain strain that may be originated from the one clone. Cross-infection control therefore is the major procedure in the prevention of MRSA dissemination in the ward.