DRUG RESISTANCE OF ESCHERICHIA COLI STRAINS ISOLATED FROM CHICKEN

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Two hundred and eighty-seven drug-resistant strains of Escherichia coli were isolated from 150 ground meat samples of chicken purchased at markets in 1978, and 210 R plasmids were demonstrated in those strains.
The most frequent resistance pattern (88%) included SA or TC resistance. The pattern associated with SM resistance was secondly frequent and the frequency of CM resistance was as low as 20%. In relation to TC, CM, SM, and SA, the isolation frequency was the highest with strains triple resistant to any combination of three of four drugs. Among the resistant E coli strains, R plasmids with single resistance to each of four drugs and those accompanying KM or APC resistance were most frequently demonstrated.
The use of antibiotics has brought many advantages to the livestock industry. The drugs not only cure the animals of bacterial infections but also accelerate growth and the increase in the body size. However, long-term administration of antibiotics has brought an increase in the number of drug-resistant organisms, especially those with conjugally transferable resistance. This paper deals with the studies on the distribution of drug resistance plasmids among E. coli strains isolated from chickens purchased at commercial markets.
We isolated 287 E. coli strains resistant to any one or any combination of the drugs tested, i.e., TC, CM, SM, SA, KM and APC. Drug-resistant E. coli strains were isolated from all chicken materials tested. SA-and TC-resistant strains were isolated most frequently (87.8% and 87.5%, respectively), followed by SM- (68.6%) and KM-resistant ones (41.8%) . The isolation frequencies of CM- and APC-resistant strains were very low, being 22.0% and 22.3%, respectively.