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

## TL;DR

This study found that many healthy dogs in Türkiye carry antibiotic-resistant E. coli with genes that confer quinolone resistance, suggesting pets may spread these resistant bacteria.

## Contribution

This is the first study in Türkiye to investigate the link between quinolone resistance genes and specific plasmid types in E. coli from healthy dogs.

## Key findings

- 40.6% of 101 E. coli strains from healthy dogs carried plasmid-mediated quinolone resistance genes (qnr).
- 19 out of 41 qnr-positive strains carried both IncK and IncF plasmid replicon types.
- IncF plasmids were more common in quinolone-resistant strains, suggesting a link between resistance and plasmid carriage.

## Abstract

Although it is well known that companion animals can serve as a source of zoonotic infectious diseases and antimicrobial-resistant bacteria for their owners, their potential role is often underestimated. To our knowledge, there are limited studies from Türkiye addressing the role of healthy companion animals in quinolone resistance. In the present study, the presence of plasmid-mediated quinolone genes, quinolone resistance, extended-spectrum beta-lactamase (ESBL) and plasmid replicon types, commonly found among fecal Escherichia coli isolates (F, K, FIB, N, FIA, FIC, and Y) were investigated. Among the 101 fecal E. coli strains examined, 41 (40.6%) were found to carry a qnr gene; of the 41 qnr-bearing strains, 19 (46.3%) harbored both IncK and IncF plasmid replicon types (p < 0.001). Our findings also suggest a possible association between qnr positivity, quinolone resistance, and IncF plasmid carriage. It may be concluded that companion animals may play a role in the dissemination of antibiotic-resistant E. coli strains.

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