Antibiotic Resistance of Bacterial Fish Pathogens

Antibiotic resistance by bacterial fish pathogens has been reported in all areas of aquaculture from warmwater to coldwater, and freshwater to marine environments. Decreased efficacy has been documented in many antimicrobial drugs regardless of their mechanism of action. Resistance emerges by two known genetic mechanisms, mutation on the bacterial chromosome, or extrachromosomal transfer mediated by plasmids. Alternatives to the currently used antimicrobial therapies are being evaluated for use in aquaculture, particularly the new fluoroquinolones and the third generation cephalosporins.