Occurrence of Antimicrobial Resistance in <i>Kocuria rhizophila</i> Bacteria Isolated From <i>Salmo munzuricus</i> (Teleostei: Salmonidae) Samples in Natural Resources

Global warming and environmental pollution trigger the emergence of antimicrobial-resistant (AMR) opportunistic pathogens in the aquatic microflora. This study aimed to determine the characterization and AMR profile of the opportunistic pathogen Kocuria rhizophila isolated from the tissues of Salmo munzuricus (Munzur trout), an endemic species. Samples collected from the Munzur River were identified using morphological and molecular (16S rDNA) methods; bacterial isolates were characterized by MALDI-TOF and sequencing. The resistance status against 11 different antibiotics was analyzed with the Kirby-Bauer method. The findings revealed that the isolates (with 99.51% accuracy as K. rhizophila) showed full resistance to Penicillin G (p < 0.01) and were moderately sensitive to gentamicin and tetracycline. High sensitivity to amoxicillin and ampicillin was detected. These findings demonstrate that even in natural environments, the fish microbiome in wild endemic populations can be susceptible to the development of AMR in response to environmental changes. Therefore, determining the resistance of opportunistic pathogens in wild fish species such as Salmo munzuricus to different classes of antibiotics and studying their spread is extremely important for natural ecosystems.