A total of two hundred and ten strains of Proteus isolated from patients in Seoul area between 1979 and 1981 were studied for drug-resistance and distribution of R plasmids. On the other hand this report dealt with the experimental results of the transmission of R plasmids from multiple-resistant strains of Proteus to Escherichia coli K-12, strain W677 and the retransmission of the R plasmid from with acquired resistance Escherichia coli K-12 to sensitive Salmonella typhimurium, Shigella flexneri and Escherichia coll.
Antibiotic susceptibilities were determined by an agar dilution method. Brain heart infusion and Mueller-Hinton agar were used for the assay of drug-resistance and propagating medium for conjugation. Proteus isolates found to be one or more antibiotics; i.e. to tetracycline (TC), chloramphenicol (CM), streptomycin (SM), sulfonamide (SA), ampicillin (AP), kanamycin (KM), and cephaloridine (CER) were considered potential donors of R plasmid to Escherichia coli K-12 RFPr. Escherichia coli K-12 RFPr obtained through the courtesy of Prof. Nagaya, Tokyo Medical and Dental Medical School, Japan was used as the resipients of R plasmids. The transfer of R plasmids was carried out by the technique of Park, et al. The method of retransfer of the R plasmid was same as the transmission of the R plasmids from Proteus to Salmonella typhimurium, Shigella flexneri and Escherichia coli, In retransmission experiments, Escherichia coli K-12 receiving R plasmid from multiple resistant strains of Proteus were used as donors. Sensitive Salmonella typhimurium No. 156 and Shigelia flexneri No. 56 which were resistant to 400 mcg and 200 mcg per ml of nalidixic acid and rifampicin, respectively were employed as the recipients of R plasmid.
The hundred eighty nine strains were found to one or more of drugs. The rate of resistant strains were 85.2% to sulfisomidine (SA), 65.6% to tetracycline (TC), 56.1% to ampicillin (AP), 53.4010 to streptomycin (SM), and 40.0% to chloramphenicol (CM) and cephaloridine (CER) respectively.
The rate of 181 multiple drug-resistant strains to TC, CM, SM, or SA was 86.8%; tripple 35.4%, double 26.0%, quadruple 25.4% and single, 13.3%.
The transfer frequency of drug resistance in Proteus species were 63.3% to AP, 63.1010 to KM, 54.4% to CM, 37.7% to SM, 28.6% to TC, and 21.7010 to CER.
Of 186 multiple resistance strains of Proteus, 63.4% harbored R plasmid; Proteus vulgaris 74.3%, Proteus morganii 80.3%, Proteus rnirabilis 44.801o, Proteus rettgeri 87.5%.
The transmitted TC, CM, and CER resistances of E. coli which received the R plasmid from Proteus were nearly as same as those of donors but SM, AP, and KM resistances transmitted from Proteus exhibited relatively lower than those of donors.
The retransmission was accomplished from resistantized E. coli to sensitive Shigella flexneri or E. coli but not accomplished from resistantized E. coli to sensitive S. typhimurium. In the former, retransmitted resistance of Shigella or E. coli were maintained after repeated subculture on drugless nutrient agar.
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