Antibiotic Resistance and Plasmid Profile of Vibrio Alginolyticus Strains Isolated from Cultured European Sea Bass (Dicentrarchus Labrax, L.)

In the study, antimicrobial resistance and plasmid profile of Vibrio alginolyticus strains isolated from diseased European sea bass (Dicentrarchus labrax, L.) collected from a commercial farm located on the Agean Region coast of Turkey, were investigated. The agent was identified by classical biochemical tests and the API 20NE system. Bacterial strains were tested for resistance to different antimicrobials by disc agar diffusion method and minimal inhibitory concentration (MIC) at two different incubation temperatures (22 ± 2ºC and 28 ± 2ºC for 24 to 28 h), and screened for plasmid DNA by agarose gel electrophoresis. It was found that 15 strains were susceptible to kanamycin but they revealed resistance to ampicillin, bacitracin and streptomycin at 22ºC. The strains were resistant to bacitracin and streptomycin but 14 strains were found to be intermediately resistant. One strain was resistant to ampicillin at 28ºC; two strains showed sensitivity to kanamycin, whereas 12 strains were intermediately resistant, and one strain was resistant to the same antibiotic at 28ºC. The strains demonstrared susceptibility to low concentrations of chloramphenicol, kanamycin, and trimethoprim (MICs of ≤ 8 μg/mL) at 22ºC. The examined strains were found to be susceptible to chloramphenicol (MICs of ≤8 μg/mL) and trimethoprim (MICs of ≤8 μg/ mL) at 28ºC. The strains harboured 2-3 plasmids, with sizes ranging from 68 to 126 kb.