Molecular characterisation of antibiotic resistance in Yersinia ruckeri isolates from Turkey

Abstract

Non-prudent use of antibiotics in aquaculture may cause the development of antibiotic resistance. The aim of the study was to determine antibiotic-susceptibility profiles of Yersinia ruckeri strains isolated from the Turkish aquaculture industry. A total of 25 Y. ruckeri strains isolated from different regions of Turkey were analysed for the determination of sensitivities to 14 antibiotics using internationally standardised disk diffusion assay. Isolates were categorised as wild-type fully susceptible or manifesting reduced susceptibility based on the COWT values calculated by Normalised Resistance Interpretation analysis (NRI). The presence of various antibiotic resistance genes (ARGs), including erythromycin (ermB and ermF), florfenicol (floR), sulphonamide (sulI, sulII, and sulIII), tetracycline (tetA, tetB, tetC, tetD, tetE, and tetG), and trimetophrim (dhfr1) were determined by PCR. Twenty five isolates were found to be fully susceptible to erythromycin, however only four isolates were categorised as showing reduced susceptibility to oxolonic acid. Tetracycline resistance (tet) genes were the most prevalent ARGs among the Y. ruckeri isolates. In conclusion, the present study provides a basis for further studies on the development of AMR in Y. ruckeri isolates derived from fish in Turkey.