The Prevalence and Antimicrobial Susceptibility of Salmonella and Campylobacter in Meat-type Chickens in Taiwan and The Results of Competitive Exclusion Trialsan

• Main Authors: Jiujiu C.H. Chou, 周崇熙
• Other Authors: Hsiang-Jung Tsai Ph.D.
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/85211167285590414628

碩士 === 國立臺灣大學 === 獸醫學研究所 === 88 === A study was conducted to estimate the prevalence and the antimicrobial susceptibility of Salmonella and Campylobacter among meat-type chickens in Taiwan. Total of 626 samples were collected from 108 flocks in 12 counties from July, 1998 to November, 1999. After the enrichment in SBM broth, the cloacal swabs samples were streaked on XLD and BPLS agar for Salmonella isolation. Then the isolates were confirmed by Salmonella antiserum. The results indicated that a total of 51out of 108 flocks (47.2%) and 64 out of 626 chickens (10.2%) were Salmonella-infection positive. S. schwarzengrund and S. typhimurium were the most prevalent serotypes (79.7%). Total of 64 isolates were tested for their antimicrobial susceptibility by disc diffusion test. The results indicated that they were more resistant to tetracycline, doxycycline, SXT, JOT, but were more sensitive to florfenicol, ciprofloxacin, ceftiofur, nitrofurantoin. The minimum inhibitory concentration (MIC) of ciprofloxacin to the Salmonella isolates showed that MIC50 was 0.125μg/mL, MIC90 was 8.0μg/mL, and 18.8 % of isolates were resistant to ciprofloxacin. The cloacal swabs were also streaked on Preston agar and incubated in a microaerophilic environment to isolate Campylobacter. The Campylobacter suspected colonies were identificated by Gram stain and the biochemical identification system API Campy®. The results showed that a total 26 out of 108 flocks (24.1 %) and 45 out of 626 chickens (7.2 %) were Campylobacter-infection positive. C. jejuni was the most prevalent serotype (66.7%). The results of antimicrobial susceptibility indicated that the Campylobacter isolates were more resistant to tetracycline, streptomycin, colistin, cephalexin, but were more sensitive to florfenicol, gentamicin, ciprofloxacin, nitrofurantoin, and the MIC of ciprofloxacin to the Campylobacter isolates showed that MIC50 was 0.38μg/mL, MIC90 was higher than 32μg/mL, and 15.6 % of isolates were resistant to ciprofloxacin. In addition, we proceeded several competitive exclusion experiments on day-old broilers. The two commercial probiotics products were used to build superiority flora in the intestines of chickens. The broilers were then challenged with the bacteria (S. enteritidis or S. typhimurium), and the infection-rate were determined over a 42-day rearing period. It was shown that there was a significant difference between the experiment and the control group in the first three weeks of age (p<0.05).