A total of 103 methicillin-resistant Staphylococcus aureus (MRSA) isolates from patients and 78 MRSA from hospital workers during the years 1990 to 1994, and 52 MRSA from patients in year 2000, in one hospital at Wakayama Prefecture, were typed by pulsed-field gel electrophoresis (PFGE) profiles. MRSA isolates were grouped into 20 genomic types. These types were further divided into 57 subtypes. The type 1 was dominant among patients, and closely related type 1 strains were spread during 1990-1993. In contrast, the type 2 was dominant among medical workers in the same period. In 2000, the type 2 and 4 strains increased, and the diversity and complication of types appeared. The common types between the patients and medical workers were only type 1 to 3. Some strains isolated from both during the same period were shown to have the same types. Others were shown to be patient-specific types. These results suggest that there are complicated transmissions of MRSA in the hospital, i.e., the endogenous infection, patient-patient cross infection and medical worker-patient cross infection.

During the years 1983 to 1999, a total of 120 Salmonella Enteritidis (SE) isolates from various sources, patient's stool, foods, kitchen wear, river water etc., in 61 cases of food poisoning in the Sakai City, were typed by pulsed-field gel electrophoresis (PFGE) after XbaI or NotI digestion of chromosomal DNA. XbaI and NotI restriction produced 2 (X1 and X2) and 3 (N1, N2 and N3) pulse-field profiles, respectively. The X1 and N1 types were further divided into 8 (Xla-Xlh) and 6 (N1a-N1f) subtypes, respectively. However, these strains of subtypes showed only 0-4 fragment changes in PFGE patterns and the index of discrimination of over 0.75, indicating that SE isolates belong to the same clonal lineage, or are revealing closely clonal relationships. These results suggested a possible strain transmission in case of food poisoning, and epidemiologically related SE isolates were spread in the Sakai City district during a long period.