J Food Prot. 2021 Nov 3. doi: 10.4315/JFP-21-292. Online ahead of print.
ABSTRACT
A series of proof of concept studies were developed to determine if a commercial bacteriophage (phage) cocktail could be utilized for the mitigation of Salmonella in bovine peripheral lymph nodes (LN). The first objective sought to determine if exogenous phage could be isolated from the LN following administration. If successful, the second objective sought to determine if once in the LN, could the phage effectively reduce Salmonella . Salmonella Montevideo was inoculated intradermally in multiple sites and administrations, later followed by delivery of the phage cocktail subcutaneously in two injections around each of the right and left prescapular and subiliac LN. At the conclusion of each study, animals were euthanized and the popliteal and above LN examined. The first study was successful, in that transmission electron microscopy revealed the presence of phage in the LN of the treated cattle, that were identical to the strains in the cocktail. Concentrations of phage were increased ( P < 0.01) in the pre-scapular and subiliac LN in the phage-treated versus control cattle. Subsequent studies modified the protocols to increase Salmonella and phage concentrations within the LN. Overall concentrations of Salmonella were increased in the LN compared to the first study and phage treatment decreased ( P < 0.01) Salmonella in the some of the LN. Phage concentrations were numerically ( P = 0.12), but not statistically, increased in the treated cattle. The final study was modified, hypothesizing that a 48h post-mortem period prior to LN removal would facilitate phage/ Salmonella interaction, however, there were no differences ( P > 0.10) in Salmonella concentrations among treatments. Results demonstrated that Salmonella- specific phages administered to live cattle can translocate to the LN, however once in the LN they had limited to no effect on Salmonella within these nodes.
PMID:34731238 | DOI:10.4315/JFP-21-292
