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

Abstract

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) bla_NDM-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.

Keywords: Pseudomonas aeruginosa; ST308; WGS; XDR; blaNDM-1; carbapenemase; cat; virulence factors.

Figure 1

Three-dimensional stacked-column chart presenting the number of ARGs per category of resistance mechanism and per class of antibacterial agents.

Figure 2

The circular map of the genome of the P. aeruginosa isolate illustrating key genetic features, including resistance determinants such as bla_NDM-1. The innermost circle illustrates the genome position, followed by a ring presenting the GC skewness. The next ring illustrates the contigs, whereas the subsequent two rings represent the presence or absence of BLAST matches at specific positions, with each ring corresponding to the WGS of the indicative NDM-1-producing P. aeruginosa strains (CP020703: ST308 strain isolated in Singapore [42] and CP053917: ST773 strain isolated in South Korea [43]). Regions covered by BLAST alignments are presented by solid colors, while white spaces denote genomic areas not covered by the alignments (created in https://proksee.ca/, accessed on 2 April 2025, the respective JSON file is provided as Supplementary File S1).

Figure 3

Focused regions of genomic variability extracted from the map shown in Figure 2. Solid-colored areas represent regions aligned by BLAST, whereas white gaps indicate regions lacking alignment coverage. Panels (a,c,d) highlight the highly conserved regions containing ARGs between the sequenced strain and P. aeruginosa strain CP020703, with notable divergence observed in strain CP053917. Panel (b) shows ARGs bla_OXA-677, rmtF, bla_PAC-1, and sul1 located within a region that displays substantial variability across all compared genomes (map created using https://proksee.ca/, accessed on 13 May 2025).

Figure 4

Sankey diagram presenting the distribution of VF-related genes identified with ABRicate per mechanism of virulence and major VF. Genes are classified according to the relevant VF category (middle column) and further classified according to the major VF they mediate (left column).