BEHAVIOR OF OXYTETRACYCLINE IN SHRIMP CULTURED Litopenaeus vannamei AND SENSITIVITY TO THREE ANTIBIOTICS OF BACTERIA OF Vibrio ISOLATED FROM THE ORGANISMS

Vibriosis is an important infection which affects the shrimp farming. Oxytetracycline (OTC) is one of the antibiotics used for its control. The maximum accumulation (C-max) and withdrawal time of OTC in hepatopancreas and muscle of shrimp were determined. The most abundant Vibrio species in shrimp was identified, as well as its sensitivity to OTC, enrofloxacin and florfenicol. Four ponds of a commercial farm were used, three received feed with OTC (5233 +/- 421 mg Kg(-1)) for 14 days, and afterward without antibiotic for 16 days. The control pond received a diet without OTC. Shrimp were sampled at days 0, 7 and 14 of the treatment, and 0, 7, 14 and 16 after withdrawal of OTC. Vibrio bacteria were isolated from muscle and hepatopancreas, molecularly identified and tested their sensitivity to OTC, enrofloxacin and florfenicol. The mean C-max of OTC was 33,45 +/- 4,11 mu g g(-1) in muscle and 223,11 +/- 89,03 mu g g(-1) in hepatopancreas, between days 2 and 12 of the therapy, respectively. The withdrawal time of OTC in hepatopancreas and muscle were at days 10 and 16, respectively. Vibrio parahaemolyticus was identified in 51% of the isolates, while V. cholerae O1 toxigenic was not found. Minimum Inhibitory Concentration for OTC, enrofloxacin and florfenicol, were 0, 75-100; 0, 25-10 and 0, 5-10 mu g mL(-1) respectively.