A total of 55 samples of intestinal contents from 28 raccoon dogs (Nyctereutes procyonoides) and 27 badgers (Males anakuma) in Miyazaki prefecture, Japan, were examined for the presence of Campylobacter species. C. jejuni and C. upsaliensis were isolated from 3.6% (n = 1) and 75% (n = 21) of raccoon dogs, respectively. In contrast, no Campylobacter spp. was isolated from the badgers examined. The C. upsaliensis isolates were subjected to antimicrobial susceptibility testing against 8 antimicrobial agents. This revealed that most of the isolates from raccoon dogs were susceptible to the antimicrobial agents examined, whereas strains isolated from healthy dogs in Miyazaki prefecture, showed high rates of resistance. Virulence genes (flaA, cadF, ciaB, cdtA, cdtB, and cdtC) were present in the C. jejuni isolate from a raccoon dog, with the exception of flaB. By contrast, all these virulence genes examined were present in all C. upsaliensis strains isolated from raccoon dogs and dogs. The genetic diversity of those isolates based on the nucleotide sequences of 7 housekeeping genes (adk, aspA, atpA, glnA, glyA, pgi, tkt) was compared with that of C. upsaliensis strains isolated from dogs and strains selected randomly from humans and dogs deposited in the Campylobacter MLST database. The major cluster of raccoon dog strains was separated from both human and dog strains by phylogenetic tree analysis. These results suggest that raccoon dogs are a reservoir of C. upsaliensis and that isolates may represent a population different from that in humans and dogs. To our knowledge, this is the first study to have demonstrated a high prevalence of C. upsaliensis in raccoon dogs.
Keywords: Antimicrobial resistance; Campylobacter; Public health; Wild life.
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