One hundred and fifty seven Escherochia coli strains isolated from 18 cattle (9 dairy cattle received penicillin, streptemycin (SM:) or sulfadinethoxine for treatment of diseases and 9 Korean native cattle not received antibiotics) were studied for the drug resistance and distribution of R factors.
Of 88 E. coli strains isolated from cattle not received antibiotics, only 1 strain was resistant to SM, but about 46 per cent of 697 E. coli strains isolated from cattle received antibiotis were resistant to SM, tetracycline (TC), ampicillin (AP), kanamycin (KM), chloramphenicol (CM), and sulfisomidine (Su), alone or in combination thereof. Of resistant strains, about 72% were resistant to three or more antibiotics, but 28% were found to singly resistant.
The most frequent resistant pattern was triple resistance to AP, KM and Su (37.6%), and quadruple one to SM, TC, CM and Sd (12.5%). About 28% of resistant strains carried R factors which wore transferable to E. coli ML 1410 NA by conjugation.
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