Bacterial Diversity and Antibiotic Susceptibility of from Aquaculture.

In a world where the population continues to increase and the volume of fishing catches stagnates or even falls, the aquaculture sector has great growth potential. This study aimed to contribute to the depth of knowledge of the diversity of bacterial species found in collected from a fish farm and to understand which profiles of diminished susceptibility to antibiotics would be found in these bacteria that might be disseminated in the environment. One hundred thirty-six bacterial strains were recovered from the samples. These strains belonged to , Family XII. , , , , , , and families. sp. was more frequently found in gills, intestine and skin groups than in muscle groups ( ≤ 0.01). Antibiotic susceptibility tests found that non-susceptibility to phenicols was significantly higher in gills, intestine and skin samples (45%) than in muscle samples (24%) ( ≤ 0.01) and was the most frequently found non-susceptibility in both groups of samples. The group of from muscles presented less decreased susceptibility to florfenicol (44%) than in the group of gills, intestine and skin samples (76%). We found decreased susceptibilities to β-lactams and glycopeptides in the family, to quinolones and mupirocin in the family, and mostly to β-lactams, phenicols and quinolones in the and families. Seven spp. and five spp. strains showed non-susceptibility to ertapenem and meropenem, respectively, which is of concern because they are antibiotics used as a last resort in serious clinical infections. To our knowledge, this is the first description of species , , sp. and associated with (excluding cases where these bacteria are used as probiotics) and of plasmid-mediated quinolone resistance -producing strain. The non-synonymous G385T and C402A mutations at gene (within quinolone resistance-determining regions) were also identified in a , revealing decreased susceptibility to ciprofloxacin. In this study, we found not only bacteria from the natural microbiota of fish but also pathogenic bacteria associated with fish and humans. Several antibiotics for which decreased susceptibility was found here are integrated into the World Health Organization list of "critically important antimicrobials" and "highly important antimicrobials" for human medicine.