Characterization of a Novel Variant of the Quinolone-Resistance Gene () Carried by a Multi-Drug Resistant Strain Isolated from Farmed Salmon in Chile.

The main objective of this study was to characterize using whole-genome sequencing analysis, a new variant of the gene () carried by a fluoroquinolone-susceptible bacterium isolated from mucus of farmed fingerling in Chile. FP75 was identified by using biochemical tests and 16S ribosomal gene analysis. Nucleotide and amino acid sequences of the gene exhibited an identity to of 81.24% and 91.59%, respectively. The genetic environment of was characterized by the upstream location of a sequence encoding for a protein containing a heavy metal-binding domain and a gene encoding for a N-acetylmuramoyl-L-alanine amidase protein, whereas downstream to gene were detected the and genes, encoding cold-shock proteins. The gene was located on a large chromosomal contig of the FP75 genome and was not associated with the 10-kb plasmid and class 1 integron harbored by the FP75 strain. This study reports for the first time the carriage of a gene by the species, and its detection in a bacterial strain isolated from farmed salmon in Chile.