닭 병원성 대장균에 대한 ofloxacin의 약제 감수성 및 치료효과 시험

In-vitro antimicrobial activity of ofloxacin to chicken escherichia coli and in-vivo therapeutic efficacy in chickens against experimentally induced colibacillosis

Ofioxacin is a new quinolone carboxylic acid as a DNA gyrase inhibitor with a broad spectrum of antibacterial activity against a wide range of bacterial pathogens. In this study it was carried out to assess the in-vitro antimicrobial activity of ofloxacin to Escherichia coli isolated from chickens with colibacillosis and to evaluate the in-vivo therapeutic efficacy of ofloxacin in chickens with experimentally induced colibacillosis. In the antimicrobial susceptibility test by the determination of minimum inhibitory concentration(MIC), MIC ranges of ofloxacin against 134 Escherichia coli strains were ditributed very broadly through 0.008 to 16 ㎍/㎖ or more than, and the drug concentration to inhibit 90% of strains tested(MIC90) was 0.25 ㎍/㎖. When 2 ㎍/㎖ is taken as the upper limit of susceptibility, all strains except one(99.3%) tested were susceptible to the drug. In the therapeutic efficacy test against an experimentally induced colibacillosis in chickens, infected and medicated groups showed significantly higher weight gain than infected and non-medicated groups. And both mortality and gross lesions of air sac, heart and liver were not observed in infected and medicated groups while there were higher mortalities(average 3.3~58.3%) and lesion socores(average 2.0~4.0) in infected and non-medicated groups.