LAUSR

AIMS Study the relationship between antibiotic resistance patterns of Pseudomonas isolated from farmed rainbow trout fillets and farm or transformation process locations. METHODS AND RESULTS Pseudomonas strains were isolated from rainbow trout sampled in two differently located farms and filleted in laboratory or in a processing factory. One hundred and twenty-five isolates were confirmed as belonging to Pseudomonas using CFC selective media, Gram staining, oxidase test and qPCR methods. Fifty-one isolates from separate fish fillets were further identified using MALDI-TOF mass spectrometry, and the minimal inhibitory concentrations (MIC) of eleven antibiotics were also determined by microdilution method. Most of the isolates belonged to the P. fluorescens group (94.1%), and no relationship was established between antibiotic resistance patterns and sampling locations (farms or filleting areas). Multiple resistance isolates with high MIC values (from 64 µg.mL-1 to more than 1,024 µg.mL-1 ) were identified. CONCLUSIONS Antibiotic resistance patterns found in Pseudomonas isolates were not influenced by farms or transformation process locations. Seven isolates were found highly resistant to four different antibiotic classes. SIGNIFICANCE AND IMPACT OF THE STUDY This study does not provide evidence of a relationship between of farm or transformation process locations on antibiotic resistance patterns of Pseudomonas population.