Investigation of Antimicrobial Resistance and Prevalence of Tetracycline Resistance Genes among Escherichia coli Isolated from Dairy Cattle in Taiwan

• Main Authors: Tsan-Pai Yu, 余璨百
• Other Authors: Shih-Te Chuang
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/20639303263693362549

碩士 === 國立中興大學 === 獸醫學系暨研究所 === 100 === Antimicrobial resistance is a growing concern for public in recent decades. It had been showed that antimicrobial resistance isolates could be threats to human via direct or indirect contact and food chains. Escherichia coli is one of the most common pathogens which causes diseases such as mastitis, diarrhea, uterine infection, pneumonia, abscess, and omphalitis in dairy farms. The objective of this study was to invetigate the antimicrobial resistance and the prevelance of tetracycline resistance genes among E. coli isolated from healthy cattle and clinical cases in dairy farm by using antimicrobial susceptibility test and specific oligonucleotide primers for amplifying six genes: tetA, tetB, tetC, tetD, tetE, and tetG. In the result of this study, a total of 320 E. coli were obtained, including 150 enteric E. coli from healthy cattle, 126 E. coli from milk samples, 33 E. coli from diarrhea, 5 E. coli from uterine infection, 2 E. coli from omphalitis, 2 E. coli from abscess, and 2 E. coli from pneumonia cases. Among 13 antimicrobial agents tested, the resistance was most frequently examined for oxytetracycline (42.5%), tetracycline (38.4%), amoxicillin (29.1%), ampicillin (27.5%), and sulfamethoxazole/trimethoprim (20.9%). Multidrug resistance was noted in 27.5% of E. coli. The multidrug resistance was significantly higher in the isolates from milk and diarrhea samples than enteric isolates from healthy cattle; in addition, the isolates from diarrhea samples was significantly higher than the isolates from milk samples. The result of multiplex PCR revealed that 40.6% isolates containing at least one of the tet genes, and tetA (23.4%) was the most frequently identified among 320 E. coli; whereas tetB (15.0%), tetC (4.7%) and tetD (0.6%) were less. The multidrug resistance was significantly higher in the isolates containing tetracycline resistance genes (53.5%) than the isolates without containing tetracycline resistance genes (10.0%).