Submitted to: International Aquatic Animal Health Symposium Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: July 18, 2002
Publication Date: September 1, 2002
Citation: DARWISH, A.M., RAWLES, S.D., GRIFFIN, B.R. DOSE TITRATION OF OXYTETRACYCLINE AGAINST STREPTOCOCCUS INIAE INFECTION IN BLUE TILAPIA. . INTERNATIONAL AQUATIC ANIMAL HEALTH SYMPOSIUM PROCEEDINGS. 2002. p.113. Technical Abstract: Experimental trials were performed to evaluate the efficacy of oxytetracycline (OTC) in controlling Streptococcus iniae infection in blue tilapia, Tilapia aurea. Minimum-inhibitory-concentration studies of OTC against multiple S. iniae isolates indicated general sensitivity at concentrations of 0.25-0.5 g/mL. Oxytetracycline dose levels tested were 25, 50, 75 and 100 mg active ingredient per kilogram of fish body weight per day. Administration of medicated feed started within 4-5 h after infection by waterborne exposure to S. iniae (after skin scraping) and continued for 14 consecutive days, followed by a 21 d post-treatment observation. The 50 mg OTC treatment significantly increased the survival of the infected tilapia from 7 % in the infected non-medicated group to 45 %. The 75 and 100 mg OTC treatments had survival rates (85 and 98 %, respectively) significantly higher than the 50 mg treatment. There was no significant difference between the 75 and 100 mg treatments and the uninfected non-medicated treatment (100 % survival). Survivors of the 100 mg OTC treatment were not detected to be carriers of the infection (negative bacterial isolation) whereas the bacterium was recovered from 10 % of the survivors receiving the 75 mg OTC level.