A potential route of Campylobacter spp. dissemination to internal tissues of broilers and sensitivity of Campylobacter enrichment procedures
Richardson, Larry Jason
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The overall aims were to 1) investigate the circulating blood as a potential route of Campylobacter spp. dissemination to internal tissues and organs within broilers, 2) evaluate the sensitivity of cultural procedures for recovery of Campylobacter spp., and 3) determine whether Campylobacter strains enter into a viable but non-culturable state after subjection to dry-atmospheric-temperature stress. Circulating blood was demonstrated to contain viable Campylobacter spp. and a potential dissemination route of Campylobacter spp. to internal tissues and organs. Seven Campylobacter subtypes were aseptically recovered from the circulating blood of broilers from 9 of 19 broiler flocks at a rate of 11.5%. Isolates differed in invasiveness into polarized Caco-2 cells, ranging from no invasiveness to 1.25%. Blood and ceca isolates from the same bird differed in invasiveness but were similar by flaA SVR DNA sequencing. In separate studies, two enrichment broths (TECRA and Bolton enrichment broth) and twelve different enrichment procedures (using the two broths) were evaluated for their sensitivity to recover Campylobacter spp. from rehang and post-chill carcass rinses. Sensitivity of recovery was influenced by enrichment method, enrichment broth, plant, and sample type. Carcass rinses at rehang contained higher numbers of Campylobacter and non-Campylobacter cells than at post-chill. The antibiotics in TECRAbroth significantly reduced background microflora when compared to the antibiotics in Bolton broth, which influenced sensitivity. The best procedure for rehang samples used TECRA broth, incubated microaerophilicly at 42ºC for 5 h without antibiotics followed by the addition of antibiotics for an additional 43 h incubation. The best procedure at post-chill used TECRA broth incubated microaerophilicly at 37ºC for 5 h without antibiotics followed by the addition of antibiotics and incubation at 42ºC for an additional 43 h incubation. The best Bolton broth procedure for rehang and post-chill was microaerophilic incubation at 42°C for 48 h with antibiotics and 5% lysed horse blood. An increase in Campylobacter spp. recovery from samples were observed when using the best TECRAand Bolton enrichment procedure together for each sample. When marker Campylobacter spp. were exposed to dry-atmospheric-temperature stress for 24 h, C. jejuni and C. coli could not be significantly recovered after 2 h and was unrecoverable after 6 h of exposure using the best methods from the above studies. However, using a chick bioassay, Campylobacter strains were still viable from the culture negative (6 h and 24 h) samples.