Studies on the Pathogenic E. Coli V. Sensitivity of pathogenic E. coli against antibiotics

Abstract

Three hundred and thirty two pathogenic strains of E. coli (13 types) isolated during 4 years (1956-1959) in Tochigi Prefecture were investigated on their sensitivity against various antibiotics.
All of the 138 strains isolated in 1956-1957 were sensitive against antibiotics. Twelve (6.2%) out of 194 strains examined in 1958-1959 were resistant against antibiotics.
Among these, one strain (O-28 a, c) was resistant against streptomycin, 10 strains (7 strains of O-126 and 3 strains of O-128) against tetracycline alone and another one strain (O-126) against streptomycin and tetracycline.
Out of 12 strains, one (O-28 a, c) was isolated from a sporadic case, a healthy adult, whereas all the other strains were obtained from epidemic cases of a sucklings' home.
Regarding the grade of resistance, 88.2% of the strains isolated demonstrated a resistance of 3.12-6.25 γ/cc against chloramphenicol, 92.5% a resistance of 1.56-3.12 γ/cc against streptomycine and 87.5% a resistance of 1.56-3.12 γ/cc arainst tetracycline, respectively.
Antibiotic-sensitivity was not at all related to the type of strains, however, O-124 demonstrated a little lower value as compared with the other types.
Examination on the antibiotic-sensitivity of ordinary E. coil isolated from 448. persons revealed that none of the strains were resistant against chloramphenicol.
Tetracycline-resistant strains were sought from 172 persons, revealing resistant strains (100 γ/cc) in 16 persons (9.3%). Most of them had been once treated with tetracycline.