Phenotypic and Genotypic Antimicrobial Resistance of Lactococcus Sp. Strains Isolated from Rainbow Trout (Oncorhynchus Mykiss)

A current profile of antimicrobial resistance and plasmid of 29 Lactococcus garvieae and one Lactococcus lactis strains isolated from rainbow trouts (Oncorhynchus mykiss) from farms throughout Turkey were investigated. All isolates were sensitive to penicillin G (90%), ampicillin (86.7%), florfenicol (83.3%), amoxicillin (80.1%), and tetracycline (73.4%), and resistant to trimethoprim+sulfamethoxazole (86.6%) and gentamycin (46.6%) by disc diffusion method. Twenty-eight (93%) isolates had two to seven antibiotic resistance genes (ARGs) determined by PCR. The most prevalent ARGs were tetracycline (tetB), erythromycin (ereB), and β-lactam (blaTEM). Bacterial strains were also screened for plasmid DNA by agarose gel electrophoresis and two strains harboured plasmids, with sizes ranging from 3 to 9 kb.