乳汁에서 分離된 大腸菌의 特性에 관한 硏究

Studies on the characteristics of escherichia coli isolated from raw milk

This study was conducted to examine the characteristics of Escherichia coli isolated from raw milk which were collected from the part of Kyunggi and Kangwon province from July 1995 to May 1996. It was performed to investigate serotype, antibiotic susceptibility, plasmid pattern, production of verotoxin and colicin. Also, it was studied for the transferable pattern of drug resistance by conjugation. The results obtained from this study were summarized as follows. 1. A total of 81 E. coli were isolated from 1,640 samples of raw milk. 2. After examining the drug susceptibility of the isolated E. coli against antimicrobial agents, we found that 60.5% of the isolated E. coli resisted against several antimicrobial agents, especially with showing multi-resistant pattern to 49.8%. 3. The transferable frequency of drug resistance in the multi-resistance was higher than in the single-resistance by conjugation test with either similar or different species of bacteria. Also, there was no difference in transferable ratio of drug resistance between similar and different species. 4. By conjugation test in E. coli, plasmids of 4.2~6.8kb were suggested as factors related with muli-resistance against antimicrobial agent. 5. Of 81 the isolated E. coli, 11 strains(13.5%) have colicin producing ability, 2 strains(2.4%) verotoxin and 16 strains(19.7%) β-hemolysin.