Antimicrobial activity, toxicity and effect of norfloxacin for experimental coli-bacteriosis of laboratory animals
The aim of this study was investigation of pharmacological and toxicological properties of norfloxacin and detection of its therapeutic and preventive effect against experimental Escherichiacoli infection in laboratory animals. Norfloxacin MICs of investigated E.coliisolates were 0.001-0.5 μg /ml. Acute toxicity was defined in white mice by different routes of administration. Norfloxacin was administered orally in doses 1000-2400 mg/kg of body weight with the interval between doses 200 mg; parenterally in doses 100-800 mg/kg with the interval 100 mg. LD<sub>50</sub> for white mice was 2320 (1966-2737) mg/kg if administered orally, and 450 (349 -580) mg/kg if administered parenterally. 200 white mice used for investigation of a therapeutic and preventive effect of norfloxacin in experimental colibacteriosis. White mice were experimentally infected by intraperitoneal route with overnight culture of E. coli in the concentration 1.5x108 CFU/0.5 ml. The antibiotic was given orally one time. A therapeutic effect of norfloxacin was defined for following doses: 2,5; 5; 7,5 и 10 mg/kg. A preventive effect was defined by oral administration of antibiotic in dose 10 mg/kg of body weight an hour, 3 and 6 hours before mice were infected. As the result, the most therapeutic effect of norfloxacin has been shown in doses 7,5 and 10 mg/kg (81 and 87%). A maximal preventive effect of norfloxacin was observed if administered orally six hours before laboratory animals were infected.