Comparative efficiency of some commercial antibiotics against Pseudomonas infection in fish

Abstract

Pseudomonas sp is a gram-negative, rod shape bacterium belonging to the family Pseudomonadaceae. The species is highly adaptable opportunistic pathogen, capable of surviving in a variety of environment, including aquaculture environment. Antibiotics are used in the aquaculture environment, and their improper usage poses a risk of potential transfer of resistance from aquaculture bacteria to human and animal pathogens. This study was conducted to isolate Pseudomonas sp from infected fish and their antibiotic susceptibility pattern also investigated by using different antibiotics. All of the isolates tested were sensitive to applied antibiotics at different doses. In bactericidal activity, the oxytetracycline showed lowest number of colonies (1×10-4 c.f.u./ml), tetracycline showed moderate number of colonies (2.5×10-4 c.f.u./ml) and ciprofloxacin showed highest number of colonies (4.5×10-4 c.f.u./ml). In antibiotic susceptibility testing the zone of inhibition was found for oxytetracycline was 24mm, tetracycline was 21 mm and ciprofloxacin was 18 mm. In agglutination titer, oxytetracycline showed better result than tetracycline and ciprofloxacin any kind of different doses. The highest Relative percent survival (RPS) value found for Oxytetracyline was 72.2%, RPS value for tetracycline was 50% and lowest RPS value found for ciprofloxacin was 33.33%. Based on the results of this study, it can be said that oxytetracycline can be more effective antibiotics than tetracycline & ciprofloxacin for the treatment of Pseudomonas infection in fish.