| Summary: | 碩士 === 國立臺灣大學 === 獸醫學研究所 === 97 === Antimicrobials had been used for therapy and prevention of infectious disease in human and domestic animals as well as to promote growth in animals. Studies indicated that increasing of antimicrobial resistance in bacteria was caused by selection pressure from drug-abuse and sub-therapeutic dosage used in a long-term manner. Resistance genes could transfer among bacteria by plasmids, increasing the probability of transfering resistance genes form human to animals and vice versa, which could result in therapy failure in clinical practice.
300 rectal feces swabs were collected from farrow-to-feedlot swine herds by stratified random sampling in the northern, middle and southern Taiwan from June 2006 to May 2007. A total of 256 E. coli isolates were identified by API 20E kit, and reconfirmed with polymerase chain reaction (PCR) comparing to ATCC 25922 E. coli. There were 75, 86 and 95 isolates collected from northern, middle and southern Taiwan respectively. All E. coli isolates were analyzed for their antibiogram and prevalence of blaTEM-1, blaSHV-1, blaCTX-M-1, floR, cmlA, and gene cassettes of class I integron including dfr12-orfF-aadA2, dfr17-aadA5, aadA1 and aadA2 by PCR. The susceptibility test results showed that more than 70% of the isolates resistant to ampicillin, amoxicillin, oxytetracycline, florfenicol and chloramphenicol, while sensitive to colistin. The prevalence results were that floR 90.3% and cmlA 91.1%; blaTEM-1 70.7%, blaSHV-1 67.2%, class I integron 51.6% and blaCTX-M-1 38.7%, respectively.
This study demonstrated that the genes of floR, cmlA, blaTEM-1, blaSHV-1 and class I integron were widely distributed. In addition, both middle and southern swine herds had significantly higher resistances to amoxicillin, ampicillin, oxytetracycline, florfenicol, chloramphenicol and nalidixic acid than those swine herds in northern Taiwan. The antimicrobial susceptibility results could be useful for veterinary clinical practice in the selection of antimicrobials. It would be necessary for a long period surveillance and monitoring of the antibiogram and resistance genes of indicator bacteria such as E. coli. The determinant factors for the development of resistance genes also need to be clarified.
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