Determination of disease pathogen Stenotrophomonas maltophilia bacteria and trimethoprim–sulfamethoxazole resistance genes by molecular methods in rainbow trout (Oncorhynchus mykiss) in Tunceli province

One of the fish farmed in our country is Rainbow trout (Oncorhynchus mykiss), but many other fish species are also consumed and bred. One of the bacteria that causes pathogenic effects in these fish is Stenotrophomonas maltophilia (S. maltophilia). The aim of this study is to identify the S. maltophilia bacteria, one of the pathogenic bacterial species that causes various infections in Rainbow Trout, which is produced in aquatic environments and is a major food source for humans, using the MALDI-TOF MS method and to identify the virulence genes that cause pathogenic effects. In this study; Tail rot, fin rot, hemorrhagic septicemia, darkening of the skin, swimming disorders and ulcers etc. have been reported in the net cages and concrete pools where rainbow trout are grown in the Mazgirt, Çemişgezek, Ovacık and Pertek districts of Tunceli province. Isolation of S. maltophilia bacteria, which spread in the organs of these fish such as intestines, kidneys, spleen, skin, liver and gills, by culture method, by taking 200 juvenile or adult rainbow trout showing disease symptoms such as MALDI-TOF MS (Matrix Assisted Laser Desorption/Ionization Method).) was identified using the method. At the end of our study, the distribution of S. maltophilia bacteria according to districts, the effect of production methods on bacterial reproduction, the reproduction rates of this bacterium by months, the reproduction percentages of this bacterium in organs such as intestines, kidneys, spleen, skin, liver and gills of rainbow trout, the prevalence of S. maltophilia The sensitivity and resistance status on TMP/SMX and the antibiotic sensitivity and resistance of the sul1 and sul2 genes of the bacterium were investigated. In the study, 5 (5.10%) were sensitive to the sul1 gene and 92 (94.90%) were resistant; In the sul2 gene, it was observed that there were 97 susceptible (100%) and 0 resistant (0%). At the end of our study, considering that bacteria, especially virilence genes, show resistance to multiple drugs, necessary studies should be carried out for multi-drug treatment, especially improvement studies should be carried out due to the high potential of TMP/SMX resistance to increase through mobile genetic elements, and our study will inform trout farmers about the methods they will apply to prevent diseases. It is important as a guide.