Antibiotic Resistant Bacteria in the Gut of Hatchery-Reared Tilapia and Coho Salmon
Experiments were conducted to investigate the presence of antibiotic resistant bacteria in hatchery-reared fish that are important in commercial aquaculture. Two fish species, tilapia (Oreochromisniloticus) and cohosalmon(Oncorhynchuskisu tch)were obtained from certified hatcheries to investigate ifantibiotic resistant bacteria are present in their guts. The antibiotic resistant bacteria were isolated on the basis of their resistance to ampicillin. Six out of 8 tilapia and 3 out of 8 salmon yielded antibiotic resistant isolates. These results indicated prevalence of antibiotic resistant bacteria in guts of both fish species. Five bacterial isolates were taken from each of these nine fish that yielded ampicillin resistant bacteria (45 bacterial isolates in total) to test antibiotic sensitivity using six additional antibiotics: penicillin, vancomycin, chloramphenicol, tetracycline, streptomycin, and gentamicin. In addition to ampicillin, all isolates showed resistance to penicillin and sensitivity to gentamicin.Overall, ten different resistance phenotypes were observed and many isolates displayed multidrug resistance.