대장균의 R plasmid의 특성과 항균제 내성

Abstract

One hundred and four strains of Escherichia coli isolated in Taegu area were tested for the antimicrobial susceptibility to 15 drugs. All strains were susceptible to amikacin (AK) and moxalactam(MX). 1.9-3.9% of the strains were resistant to cefamandole(Cmd), nalidixic acid(Na) and rifampin(Rf)，and 18.3-21.2% were resistant to gentamicin and cephalothin.41.3%-57.7% were resistant to kanamycin, streptomycin (Sm), chloramphenicol (Cm), and trimethoprim(Tp).67.6-83.7% were resistant to penicillin(Pc), ampicillin(Ap), tetracycline(Tc), and sulfamethoxazol(Smx). MIC90 of Ak, Mx, amd Na was 8μg/mL MIC90 of other drugs were about 16-l,024μg/ml. Strains multiply resistant to the 8 drugs, Cm, Tc, Sm, Smx, Ap, Km, Tp, Pc were most frequently encountered. Most of drug resistances except to Na and Rf in 75.3% of resistant strains were co-transferred to recipient E. coli RG176 or RG488, indicating that multiple drug resistances were R plasmid mediated phenomenon. Plasmid profiles for molecular characterization of R plasmids from E. coli strains were studied through the methods of alkaline SDS lysis and agarose gelectrophoresis. Most of R plasmids were 63.2 to 79.8 Mdal in molecular size. EcoRJ restriction enzyme digestion patterns of R plasmid DNAs were examined. R plasmid of 79.8 Mdal in size had 13 DNA fragments, their molecular sizes were 4 to 25 kilobase R plasmids of 63.2 Mdal in size had 7 to 16 fragments, 3 to 25 kilobase in size and those of 66.8 Mdal in size had 11 fragments, 8 to 25 kilobase in size. Key Words: Escherichia coli，R-plasmi