Isolation and characterization of Staphylococcus aureus in rats trapped at restaurants in buildings in downtown Tokyo

165 (18.1%) out of 910 rats captured at restaurants in 14 buildings in downtown Tokyo were positive for Staphylococcus aureus. The 165 S. aureus strains isolated were biotyped into A, B, C, D, G, and untypable groups (UT1 and UT2). The UT1 was the most frequent (72 strains, 43.6%), followed by biotype G (33 strains, 20.0%). The strains were classified into coagulase types I, II, III, IV, V, VI, VII, VIII, and an untypable group. Coagulase type V was the most frequent (92 strains, 55.8%), followed by coagulase type VII (25 strains, 15.2%). Enterotoxins A, B, C, or D were produced by 35 strains. Enterotoxins A and B were the most frequent (13 strains each). Toxic shock syndrome toxin-1 was produced by 3 strains. 65 strains were resistant to ampicillin, 2 to oxytetracycline, and 1 to erythromycin.