Plasmid-Mediated Quinolone Resistance Genes in Escherichia coli Strains Isolated from Healthy Dogs

Knowledge about the potential roles of pets as reservoirs for plasmid-mediated quinolone resistance is still limited in Türkiye. Thus, in our study, the presence of plasmid-mediated quinolone genes (<i>qnrA</i>, <i>qnrB</i> and <i>qnrS</i>) was examined by multiplex Polymerase Chain Reaction (PCR) in 101 fecal <i>Escherichia coli</i> (<i>Escherichia coli</i>) strains isolated from healthy dogs. Moreover, the relationship between the presence of <i>qnr</i> genes and prevalence of quinolone resistance, extended spectrum beta-lactamase (ESBL) and plasmid replicon types, mostly detected among fecal <i>E. coli</i> isolates (F, K, FIB, N, FIA, FIC, and Y) were investigated. A total of 41 strains (40.6%) carried at least one <i>qnr</i> gene. <i>Qnr</i> genes were found in 38.8% of quinolone-resistant and 40.9% of quinolone-susceptible strains. ESBL production was detected in 27 strains, 10 of which also harbored a <i>qnr</i> gene. Among <i>qnr</i>-positive strains, 19 (46.3%) carried both IncK and IncF plasmids (<i>p</i> < 0.001). IncF plasmids were significantly more prevalent in quinolone-resistant strains than in susceptible ones (<i>p</i> < 0.001), suggesting a potential link between <i>qnr</i> carriage, quinolone resistance, and IncF plasmids. To our knowledge, this is the first study investigating the relationship between <i>qnr</i> genes and specific plasmid replicon types in <i>E. coli</i> from healthy dogs in Türkiye. Our findings suggest that domestic animals may serve as reservoirs for antibiotic-resistant <i>E. coli</i>, underscoring the importance of a One Health approach.