Analysis of antimicrobial sensitivity in Yersinia ruckeri strains isolated from Oncorhynchus mykiss in fish farms of Ayacucho, Peru

Apayco-Espinoza N.A.; Urrutia-Zegarra A.A. · Revista de Investigaciones Veterinarias del Peru (2025) · DOI: 10.15381/rivep.v36i2.26556

Resumen

The cultivation of rainbow trout (Oncorhynchus mykiss) has experienced a significant increase in Ayacucho, Perú, leading to a rise of infection diseases, including «red mouth» caused by Yersinia ruckeri. This pathogen is typically managed with broad-spectrum bacteriostatic antibiotics, raising concerns about antimicrobial resistance. The primary objective of this investigation was to analyse the antimicrobial sensitivity profiles of Y. ruckeri strains isolated from O. mykiss in two aquaculture farms located in Vinchos district, Ayacucho. A non-experimental, descriptive cross-sectional design was employed. Ten clinically affected juvenile trout were sampled per farm, and Y. ruckeri was isolated using microbiological techniques. Bacterial identification was confirmed through biochemical assays and conventional PCR. Antimicrobial susceptibility testing was performed via the Kirby-Bauer disk diffusion method. It was observed that three strains exhibited resistance to oxytetracycline while one strain showed resistance to florfenicol and chloramphenicol in the first fish farm. In the second farm, four strains demonstrated resistance to tetracycline. Overall, resistance rates to tetracycline and oxytetracycline across both farms were below 30%. These findings highlight emerging resistance patterns in Y. ruckeri and underscore the need for prudent antibiotic use in aquaculture to mitigate resistance development.

Instituciones: Universidad Nacional de San Cristóbal de Huamanga