The Effects of Antimicrobial Residues on Microbiological Content and the Antibiotic Resistance in Frozen Fish

As fish are perishable foods, their storage conditions require appropriate sanitary and temperature regimes. The producers commonly use various antibiotics to stop fish’s microbiological and biochemical processes. The current research aimed to examine antibacterial residues in frozen fish (Argentina, flounder, lackerda, mackerel, capelin, salka, saithe, herring, dorado, and pink salmon) to find their influence on the quantitative content of microorganisms and to determine the sensitivity of isolated psychrotrophic bacteria to antibiotics. A total of 75 samples were collected from the fillets of frozen fish species. These fish were imported from Norway (16 samples), Vietnam (24 samples), Russian Federation (8 samples), China (14 samples), New Zealand (2 samples), Italy (2 samples), United States (4 samples), and United Kingdom (5 samples). The obtained results revealed that aminoglycosides (Gentamicin, Kanamycin, Spectinomycin, Dihydrostreptomycin, Paromomycin, and Apramycin) were in 45.6 ± 1.4% of frozen fish. The findings indicated the presence of some antibacterial residues (Nalidixic acid, antibiotics: Apramycin, Kanamycin, Tiamulin, and Nafcillin) in frozen fish, the definition of which has not been specified in the EU Regulation. This gives grounds to prohibit the use or develop standards for the maximum permissible concentration of these antibacterial substances in fish. The most common psychrotrophic bacteria isolated from frozen fish without antibacterial residues were highly sensitive to antibiotics, including Penicillin, Tetracycline groups, and Aminoglycosides. Therefore, it can be concluded that the residual levels of various biocides found in fish are a source for the expression of multi-resistance genes, which can be transmitted to consumers in the food chain.