Evaluation of antibiotic resistance pattern of Streptococcus iniae and Lactococcus garvieae isolated from diseased rainbow trout (Oncorhynchus mykiss) farmed fish in Chaharmahal and Bakhtiari province

Streptococcus iniae and Lactococcus garvieae bacteria are among the most important fish pathogens. The aim of this study was to determine antimicrobial resistance patterns of S. iniae and L. garvieae isolated from diseased rainbow trout. With respect to outbreak of disease, the survey was carried out in warm seasons using 100 rainbow trout fish with clinical symptoms of disease. Bacteria were cultured from Kidney tissue of fish using standard methods. The antibiotic resistance pattern of strains was studied based on CLSI protocol. The results of the research showed that S. iniae isolates were more sensitive to enrofloxacin, florfenicol, erythromycin and lincospectin, and more resistant to sulfamethoxazole-trimethoprim, tetracycline, fosfomycin, ampicillin, lincomycin and flemequine, respectively. Furthermore, L. garvieae isolates were more sensitive to erythromycin, enrofloxacin, florfenicol, flemequine and lincospectin, and more resistant to sulfamethoxazole-trimethoprim, fosfomycin, tetracycline and ampicillin.