Genomic characterization of Pseudomonas aeruginosa from canine otitis highlights the need for a One Health approach to this opportunistic pathogen

In humans, <i>Pseudomonas aeruginosa</i> is well known as a prominent opportunistic pathogen associated with antimicrobial resistance (AMR), which presents a major challenge to successful treatment. This is also the case in animals, particularly in companion dogs where <i>P. aeruginosa</i> is a common cause of otitis. Despite its clinical significance, little data are available on the genomics and epidemiology of <i>P. aeruginosa</i> in dogs. To address this, we have genome-sequenced 34 canine otitis <i>P. aeruginosa</i> isolates from a veterinary referral hospital and analysed these along with a further 62 publicly available genomes from canine isolates. Phylogenetic analysis revealed that all three <i>P. aeruginosa</i> phylogroups<i>,</i> A-C<i>,</i> are represented amongst a diverse bacterial population isolated from dogs. We identify examples of persistent or recurrent infection by the same strain of up to 309 days between sampling, demonstrating the difficulty of successfully eradicating infection. Isolates encoded a variety of AMR genes with genomic and phenotypic AMR correlating poorly for β-lactams but showing complete concordance between fluoroquinolone resistance and quinolone resistance-determining regions (QRDRs) of DNA gyrase and topoisomerase IV. Pangenome-wide analysis between 80 canine otitis isolates (34 newly sequenced here and a further 46 publicly available) and a reference collection of 491 human isolates found no genes which were over-represented or specific to either host species, indicating similar strains infect both humans and dogs. This agrees with the sharing of multilocus sequence types between dogs and humans, including the isolation here of ST235 from three dogs, a lineage prominent among the multidrug resistant (MDR) and extensively drug-resistant (XDR) international high-risk clones of <i>P. aeruginosa</i> causing human infections. The presence of such 'high-risk' clones in companion dogs is concerning given their potential impact on animal health and the potential for zoonotic spread. These data provide new insight into this difficult-to-treat veterinary pathogen and promote the need for a One Health approach to tackling it.