[Nosocomial infections due to methicillin-resistant S. aureus (MRSA) at the Kagoshima University Hospital (1). Coagulase typing of MRSA].

Nosocomial infection due to MRSA at the Kagoshima University Hospital and their coagulase typing were examined using S. aureus (349 strains) clinically isolated in 1989. The results were as follows: 1) S. aureus consisted of 43.6% of MRSA and 56.7% of Methicillin-sensitive S. aureus (MSSA). 2) MRSAs were recovered most frequently from the specimens from the respiratory tract (47.8%). 3) The isolation of MRSA gradually increased in frequency from January to August; however, that of MSSA did not show a similar tendency. 4) The isolation of MRSA was higher in frequency in the surgical wards, the ICU and the pediatric ward. 5) When classified into 8 coagulase types, MRSAs (133 strains) consisted of only 3 types (54.1% of type II, 32.3% of type VII, and 12.0% of type IV), whereas MSSAs contained all coagulase types. As compared with the results of coagulase typing at other institutions, the incidence of type VII was much more frequent at our hospital. 6) A few coagulase types of MRSA appeared in each ward. Also, type II MRSA strains increased in June and July, and type VII MRSA increased in August. However, MSSA strains did not show any similar tendency.