Potentiality of Selected Commercial Antibiotics Challenged with Aeromonas sp.

This study was intended to address, the effect of oxytetracycline, erythromycin, and streptomycin on the antimicrobial resistance of Aeromonas sp. isolated during the production process, from infected common carp (Cyprinous carpio). Antimicrobial resistance patterns were defined by determination of minimal inhibitory concentrations (MIC) of three antimicrobial drugs, and bacteria. Results indicated that In vitro bactericidal activity, oxytetracycline showed lowest number of bacterial colonies (1×10⁻⁴ c.f.u./ml) than erythromycin (3×10⁻⁴) and streptomycin (4.5×10⁻⁴) compared to the control (9×10⁻⁴). Oxytetracycline showed the highest maximum zone of inhibition (20 mm) than erythromycin (18 mm) and streptomycin (15 mm) in antibiotic susceptibility test. In infection inhibition assay, serum from oxytetracycline fed diets inhibited Aeromonas infection to common carp. The susceptibility of the fish fed antibiotics (50 µg/mg feed) and challenge with Aeromonas sp. (1×10⁻⁴) was examined for 30 days. There was high relative percent of survivility (RPS) in oxytetracycline was 73%. Very low RPS 63% and 47.37% was found in erythromycin and streptomycin against Aeromonas sp. infection. These results demonstrated that the oxytetracycline might be a potential for Aeromonas sp. infection to common carp (Cyprinous carpio).