[A nationwide study of the antimicrobial susceptibility of clinical isolates of Staphylococcus aureus in Japan].

We described antimicrobial susceptibilities of clinical isolates of Staphylococcus aureus in 1985 and also a 6-year survey of changing patterns of their susceptibilities to ampicillin (ABPC), cefazolin (CEZ), cefmetazole (CMZ) and gentamicin (GM) from 1980 to 1985 in 103 hospitals. The MICs were determined by the standard method of the Japan Society of Chemotherapy. Among 2,891 isolates in 1985, ratios of resistant strains to ABPC and GM were 24% and 29%, respectively, and those to CEZ and CMZ were 8% and 3%, respectively. Gradual increases in numbers of resistant strains to ABPC, CEZ and CMZ were observed until 1984 but a trend for decreases in numbers of resistant strains to the above 3 antibiotics was observed in 1985. A continuous rise in numbers of resistant strains to GM until 1985 was noted. Isolates from clinical materials such as pus, bile, and urine showed higher incidences of resistance to ABPC and GM than those from sputum, secreta and throat swab. Rates of resistant strains to CEZ were the highest in isolates from bile, pus, sputum and urine. Rates of resistant strains to CMZ were the highest in isolates from bile, and decreased in isolates from sputum, urine and pus in this order. Rates of resistant isolates from inpatients to the 4 antibiotics tested were greater than those from outpatients.