[A nationwide study of the antimicrobial susceptibility of clinical isolates of Escherichia coli in Japan].

We studied the antimicrobial susceptibility of E. coli isolated in 1983 and 1984 and also the yearly changes of the susceptibility of E. coli from 1980 to 1984 isolated in 103 hospitals in Japan. Antibiotics used for MIC determination were ampicillin (ABPC) as a penicillin, cefazolin (CEZ) as a cephalosporin, cefmetazole (CMZ) as a cephamycin and gentamicin (GM) as an aminoglycoside. Numbers of isolates tested were 2,321 strains in 1983 and 1,965 strains in 1984. CMZ was the most effective agent among the 4 antibiotics tested, followed by GM and CEZ in this order. A large number of the isolates were inhibited by 1.56 micrograms/ml on CMZ and GM and by 6.25 micrograms/ml of CEZ. About two-thirds of the isolates were inhibited at a concentration of 12.5 micrograms/ml or less of ABPC. The susceptibility of E. coli against the 4 antibiotics changed little year by year and the tendency of the appearance of resistant strains did not increase in the last 5 years.