Molecular epidemiology of clinical isolates of methicillin-resistant Staphylococcus aureus in Taiwan.

During July 2000 and October 2001, a total of 595 clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) were collected from six medical centers distributed in northern, central, and southern Taiwan. Specimen sources included blood (n = 279), pus (n = 173), sputum (n = 94), body fluids (n = 21), catheter tips (n = 20), and urine (n = 8). Pulsed-field gel electrophoresis (PFGE) with SmaI digestion was used to fingerprint these isolates. A total of 31 genotypes with 97 type-subtypes were identified. Subtypes could be identified in 7 genotypes. While there were 6 to 15 genotypes in each hospital, 433 isolates (73%) were shown to belong to a major type (genotype A, with 29 subtypes). This genotype was not only the type prevailing in all six hospitals but also the predominant clone in each hospital, accounting for 46 to 89% of all isolates in each hospital. Genotype C (16 subtypes) was the second dominant genotype, accounting for 9% of all isolates, and was distributed in five hospitals. Genotypes D (11 subtypes), E (5 subtypes), and B (6 subtypes) were distributed in five, four, and three hospitals, respectively. The other 26 types (30 type-subtypes) were minor. We conclude that the majority of MRSA clinical isolates shared a common PFGE pattern, indicating the presence of a single, epidemic MRSA clone prevailing in major hospitals in Taiwan.