Antimicrobial resistance and genotyping of Pseudomonas aeruginosa isolated from the ear canals of dogs in Japan

Abstract

The strong bond between dogs and their owners creates a close association that could result in the transfer of antibiotic-resistant bacteria from canines to humans, potentially leading to the spread of antimicrobial resistance genes. Pseudomonas aeruginosa, a common causative agent of persistent ear infections in dogs, is often resistant to multiple antibiotics. Assessing the antimicrobial resistance profile and genotype of P. aeruginosa is crucial for the appropriate use of veterinary pharmaceuticals. However, in recent years, few studies have been conducted on this bacterium in Japan. We determined the antimicrobial resistance profile and genotype of P. aeruginosa isolated from the ear canal of dogs in Japan in 2020. Analysis of antimicrobial resistance using disk diffusion tests indicated a high frequency of resistance to most antimicrobial agents. Particularly, 29 isolates from the ear canals of the 29 affected dogs (100%) were resistant to cefovecin, cefpodoxime, and florfenicol; however, they were susceptible to cefepime and piperacillin/tazobactam. Only 3.4, 10.3, and 10.3% of the isolates were resistant to ceftazidime, tobramycin, and gentamicin, respectively. Furthermore, upon analyzing the population structure using multilocus sequence typing, a considerably large clonal complex was not observed in the tested isolates. Three isolates, namely ST3881, ST1646, and ST532, were clonally related to the clinically isolated sequence types in Japan (such as ST1831, ST1413, ST1812, and ST1849), which is indicative of dog-to-human transmission. Considering the variation in antibiotic resistance compared to that reported by previous studies and the potential risk of dog-to-human transmission, we believe that the survey for antimicrobial resistance profile and population structure should be continued regularly. However, the prevalence of multidrug-resistant P. aeruginosa in dogs in Japan is not a crisis.

Pseudomonas spp. in Canine Otitis Externa

“…Very few studies have examined the genomic profiles of P. aeruginosa strains causing canine otitis specifically. Whole-genome MLST has revealed a high diversity of P. aeruginosa, with 45 different sequence types (STs) identified from 80 isolates in one study [86] and 27 STs from 29 isolates in another [87]. This mirrors studies of Pseudomonas from human infections, which also found a largely non-clonal population structure punctuated by highly successful epidemic clones/clonal complexes [88].…”

“…Fluoroquinolone resistance has frequently been reported, particularly with respect to enrofloxacin (27-68%), orbifloxacin (55-82%), and marbofloxacin (33-35%). Gentamicin resistance seems to vary greatly depending on the study, with resistance reported in 3-43% of isolates [46,48,87,[123][124][125]. Multidrug resistance, which is defined as resistance to at least one antibiotic from three or more classes [126], was recorded in 13-35% of isolates [87,123].…”

“…Gentamicin resistance seems to vary greatly depending on the study, with resistance reported in 3-43% of isolates [46,48,87,[123][124][125]. Multidrug resistance, which is defined as resistance to at least one antibiotic from three or more classes [126], was recorded in 13-35% of isolates [87,123]. Non-susceptibility to carbapenem antibiotics has also been reported in 15-23% of P. aeruginosa isolates from canine otitis [86,123].…”