Detection of Salmonella in turkeys by cloacal swab in comparison to intestinal tissue prevalence and colonization

Authors: Monson, Melissa; Bearson, Bradley - Brad; WHELAN, SAMUEL - Oak Ridge Institute For Science And Education (ORISE); BURCIAGA, SELMA - Oak Ridge Institute For Science And Education (ORISE); Bearson, Shawn

Submitted to: Conference Research Workers Disease Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 11/17/2023
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: OBJECTIVE: Human foodborne outbreaks of salmonellosis are often associated with Salmonella enterica contamination of poultry products. A non-lethal, on-farm turkey sampling method for detection of Salmonella in turkeys is desired by poultry producers for pre-harvest monitoring. Environmental sampling, such as litter grabs or boot socks, can be used for Salmonella detection at the flock level, but these methods do not assess Salmonella prevalence or load on an individual bird basis. Cloacal swabs could have utility as an antemortem sample that can be taken individually from group-housed turkeys; however, the efficacy of swabs as a predictive tool for Salmonella intestinal load needs to be further assessed in turkeys. METHODS: At seven weeks of age, male turkey poults were inoculated by oral gavage with 1 x 109 CFU of either Salmonella enterica serovar Infantis (S. Infantis) or Salmonella enterica serovar Hadar (S. Hadar); these serovars have been involved in recent foodborne outbreaks in the U.S. Randomly selected turkeys from each group were necropsied at 7- or 14-days post-inoculation with Salmonella. From each turkey, a cloacal swab was collected for Salmonella prevalence determination and Salmonella colonization levels were quantitatively assessed in cecal contents, cecum, cecal tonsil, and cloaca. Statistical analyses were performed to establish whether concurrence of Salmonella prevalence between swab and tissue samples was significantly greater than chance (i.e., >50%) and whether there was a significant relationship between Salmonella positive swabs and load in intestinal tissues. RESULTS: While Salmonella-positive cloacal swabs were likely to co-occur with Salmonella-positive cecum, cecal tonsils, or cecal contents within a given turkey (p-value <0.001 for all three sample types), many of the turkeys with Salmonella-positive intestinal tissues tested negative for Salmonella by cloacal swab (only 29-35% concurrence). Analysis of samples collected in our research study suggested that cloacal swab testing was a poor indicator of Salmonella positivity in turkeys (p-value >0.969 in all four intestinal samples). The relationship between Salmonella load in the tissues and Salmonella prevalence by cloacal swabbing trended (p-value =0.057) towards higher colonization in turkeys with Salmonella-positive cloacal swabs. CONCLUSIONS: Additional studies in both research and production settings are warranted to expand the number of matched cloacal swabs/tissue samples compared (including from turkeys naturally colonized with Salmonella) to validate the utilization of cloacal swabbing as a predictive tool for Salmonella intestinal load in turkeys as a risk indicator for product contamination.