Isolation of emerging Campylobacter species in working farm dogs and their frozen home-killed raw meat diets

We applied 7 culture methods to 50 working farm dog fecal samples and 6 methods to 50 frozen home-killed raw meat diet samples to optimize recovery of a wide range of Campylobacter spp. Culture methods combined filtration, enrichment broths, and agars at 37°C and 42°C in conventional and hydrogen-enriched microaerobic atmospheres. Overall, a prevalence of 62% (31 of 50) and 6% (3 of 50) was detected in dog and meat samples, respectively, based on Campylobacter genus PCR. A total of 356 Campylobacter spp. isolates were recovered from dogs, with successful isolation by individual methods ranging from 2 to 25 dogs. The species detected most commonly were C. upsaliensis and C. jejuni, and less commonly C. coli and C. lari. Species isolated that are rarely reported from dogs included C. rectus, C. lari subsp. concheus, C. volucris, and Helicobacter winghamensis. Six isolates from dogs positive by Campylobacter genus PCR were confirmed, using 16S rRNA sequencing, as Arcobacter cryaerophilus (1) and Arcobacter butzleri (5). C. jejuni multi-locus sequence typing results revealed a diversity of sequence types in working dogs, with several uncommonly reported from other C. jejuni sources in New Zealand. Overall, 20 isolates from 3 meat samples were positive by Campylobacter genus PCR; 1 meat sample was positive for C. jejuni, 1 for C. rectus, and 1 isolate was subsequently identified as A. butzleri. The method using Campylobacter enrichment broth in a hydrogen-enriched environment on nonselective agar resulted in significantly reduced recovery of Campylobacter spp. from both sample types.