# Companion Animals as Reservoirs of Multidrug Resistance—A Rare Case of an XDR, NDM-1-Producing Pseudomonas aeruginosa Strain of Feline Origin in Greece

## TL;DR

A highly drug-resistant Pseudomonas aeruginosa strain from a cat in Greece shows that companion animals can spread dangerous bacteria.

## Contribution

Identifies an XDR, NDM-1-producing P. aeruginosa strain from a cat, highlighting community spread beyond hospitals.

## Key findings

- The strain was resistant to all antibiotics except colistin and belonged to the high-risk clone ST308.
- It carried 67 antibiotic resistance genes and 221 virulence factor-related genes, including the blaNDM-1 gene.
- No plasmids were detected, suggesting intrinsic resistance mechanisms and environmental persistence traits.

## Abstract

Pseudomonas aeruginosa is a significant opportunistic pathogen in human and veterinary medicine. It commonly exhibits multidrug-resistant (MDR) profiles through an abundance of antibiotic resistance mechanisms. Because of its virulence and high adaptability in healthcare facilities, it is regularly implicated in challenging, severe infections, mostly in hospitalized patients. Several high-risk clones of P. aeruginosa are widely disseminated, raising concerns among healthcare professionals worldwide. In this study, an extensively drug-resistant (XDR) P. aeruginosa strain was isolated from a feline ear sample in Greece. Whole genome sequencing (WGS) was performed and the genome was assembled and submitted to identify antibiotic resistance genes (ARGs) and genes encoding virulence factors (VFs). The strain was typed as ST 308. A significant number of resistance determinants was identified, including numerous multidrug efflux pumps and the carbapenemase-producing gene blaNDM-1. Moreover, the plethora of detected VF-related genes highlighted the high virulence potential of the isolate. The results of this study indicate that high-risk bacterial clones can be disseminated in the community even outside the hospital environment. In this regard, companion animals could be infected by relevant strains, but also act as reservoirs, enhancing their further dissemination.

A backyard cat with symptoms of otitis was transferred to a veterinary clinic in Central Greece. A sample was obtained and P. aeruginosa was isolated. The strain exhibited an extensively drug-resistant (XDR) profile, as it was non-susceptible to all tested agents except colistin. DNA extraction and whole-genome sequencing (WGS) were performed using a robotic extractor and Ion Torrent technology, respectively. The genome was assembled and screened for resistance and virulence determinants. The isolate belonged to the high-risk clone ST308 with a total of 67 antibiotic resistance genes (ARGs) and 221 virulence factor-related genes being identified. No plasmids were detected. The metallo-beta-lactamase (MBL) blaNDM-1 gene and 46 efflux pumps were included in the strain’s resistome. Both ARGs conferring tolerance to disinfecting agents and biofilm-related genes were identified, associated with the ability of this clone to adapt and persist in healthcare facilities. This case highlights the risk of relevant bacterial clones spreading in the community and even being transmitted to companion animals, causing challenging opportunistic infections to susceptible individuals, while others may become carriers, further spreading the clones to their owners, other animals and the environment.