Study on antibiotic residues in Rainbow trout (Oncorhynchus mykiss) in Tabriz market

Vast application of the antibiotic drugs in animals without due attention to withdrawal times necessitates quality control of food stuff in terms of antibiotics' residues. Antibiotic residues in food stuff cause bacterial resistance, allergic reactions, toxicity, carcinogenic effects and change of natural micro flora of intestine in consumers. So, the aim of the present study is detection of antibiotic residues and its contamination rate in cultured rainbow trout. Four-plate test is one of the microbiological methods of detecting antibiotic residues in food stuff, which is based on inhibition zone formation around the sample in four culture media with different pH and test bacteria. For this purpose, 45 samples from skin and meat of rainbow trout fish were obtained randomly from fish market of Tabriz city. After different phases of four-plate test, from a total of 180 skin samples, 13 cases (7.22%) and from a total of 180 meat samples, 18 cases (10%) were diagnosed to be contaminated to antibiotic residues. The results showed that contamination rate of two tissues, (meat and skin), have no significant difference (P>0.05), and the highest contamination to antibiotic residues were related to penicillin and macrolides groups (P