Prevalences of antibiotic resistant Escherichia coli strains isolated from clinical materials in tokyo area and their conjugative R plasmids in 1978.

We surveyed antibiotic resistant E. coli strains isolated in the clinical laboratories of various hospitals around Tokyo area and their conjugative R plasmids in 1978. Incidences of antibiotic resistant strains in the clinically isolated strains were about 60% in every hospitals and materials except those in feces, where the strains contained those collected from healthy human. Frequencies of the strains resistant to sulfonamides, tetracycline, streptomycin, ampicillin, chloramphenicol and kanamycin in all resistant strains were 71, 54, 63, 52, 44 and 19%, respectively. About 40% of the resistant strains had conjugative R plasmids. Frequencies of the conjugative R plasmids carrying resistances to tetracycline, streptomycin, ampicillin, chloramphenicol, sulfonamides and kanamycin were 56, 54, 46, 40, 34 and 22%, respectively. Predominance of the single drug resistant conjugative R plasmids, especially ampicillin resistant R plasmids was new tendency of the recently isolated E. coli strains. Twenty-six % of these R plasmids were classified into Fi+ (F) type. Incidences of Fi+ (F) type R plasmids were higher in the strains isolated from pus and lower in those from feces.