Antimicrobial resistance and resistance genes in Flavobacterium psychrophilum isolates from Turkey

The antimicrobial susceptibilities of Turkish F. psychrophilum isolates were investigated using a Clinical and Laboratory Standards Institute (CLSI) standard microdilution testing protocol. The significance of the minimum inhibitory concentrations was determined by applying empirically and statistically determined epidemiological cut-off values calculated by normalized resistance analysis. Twenty-five F. psychrophilum isolates made over four years from three different trout species in five different regions were examined. All isolates were fully susceptible to amoxicillin and florfenicol, but 88% of our isolates were categorized as having reduced susceptibility to the two quinolones, oxolinic acid, and enrofloxacin. Eighty percent of the isolates were categorized as showing reduced susceptibility to oxytetracycline.