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ARS Home » Plains Area » College Station, Texas » Southern Plains Agricultural Research Center » Food and Feed Safety Research » Research » Publications at this Location » Publication #325089
Title: Efficacy of a Salmonella siderophore receptor protein vaccine on fecal shedding and lymph node carriage of Salmonella in commercial feedlot cattle

Author
item CERNICCHIARO, NATALIA - Kansas State University
item IVES, SAMUEL - West Texas A & M University
item NAGARAJA, TIRUVOOR - Kansas State University
item Edrington, Thomas
item RENTER, DAVID - Kansas State University

Submitted to: Foodborne Pathogens and Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/9/2016
Publication Date: 9/2/2016
Citation: Cernicchiaro, N., Ives, S.E., Nagaraja, T.G., Edrington, T.S., Renter, D.G. 2016. Efficacy of a Salmonella siderophore receptor protein vaccine on fecal shedding and lymph node carriage of Salmonella in commercial feedlot cattle. Foodborne Pathogens and Disease. 13(9):517-525.

Interpretive Summary: Cattle may contain the bacteria Salmonella that can make people sick. Peripheral lymph nodes in these cattle may contain Salmonella that can serve as a source of contamination of ground beef. Pre-harvest interventions such as vaccines may eliminate the Salmonella in these lymph nodes. Cattle were vaccinated in a feedlot, and feces and lymph nodes cultured for Salmonella. Results of this research found no benefit of using this particular vaccine in reducing the amount of Salmonella in the cattle’s feces or sub-iliac lymph nodes.

Technical Abstract: The efficacy of the Salmonella Newport siderophore receptor protein (SRP)® vaccine for reducing lymph node (LN) carriage and fecal shedding of Salmonella at harvest was investigated in a study of commercial feedlot cattle. The study was designed as a randomized complete block with pen as the experimental unit and two treatment groups, the Salmonella Newport bacterial extract with SRP® technology vaccine (VAC) and a negative control (CON). Cattle were randomly allocated into 24 pens within 12 blocks based on time of allocation. Twenty fecal pats were collected from pen floors once a month in June and July 2013, and 25 fecal samples per pen were collected in August 2013, 12 h before cattle were harvested. After an average of 153 days on feed, during harvest, a minimum of 25 sub-iliac LN were collected from carcasses within each study pen. Fecal and lymph node samples were cultured, using enriched broth and Rappaport Vassiliadis-Hektoen Enteric media, respectively, and spread plated (direct plating and Petrifilm plates, respectively) for Salmonella detection and quantification purposes. Generalized linear mixed models were fitted to assess the efficacy of the SRP vaccine on fecal shedding and LN carriage of Salmonella. The effect of treatment was not significantly associated (P = 0.57) with the prevalence of Salmonella in feces over time; model-adjusted cumulative within-pen prevalence was 62.3% and 66.0% among vaccinates and controls, respectively. Month of sampling was significantly associated (P < 0.01) with the within-pen fecal prevalence of Salmonella. Model-adjusted cumulative fecal prevalence was 71.4% for June, 48.6% for July, and 70.8% for August. Across all pens, cumulative prevalence of Salmonella in LN was 86.4% based on culture-based methods. Administration of the SRP vaccine resulted in no significant reduction in prevalence of Salmonella in LN (P = 0.52): mean prevalence was 85.5% for cattle in the VAC and 87.3% for cattle in the CON group. The study animals in this commercial feedlot had an extremely high burden of Salmonella. Although cattle receiving the SRP vaccine had numerically fewer Salmonella LN and fecal positives, there were no statistically significant vaccine effects. Potential reasons for the apparent lack of vaccine efficacy could include an overwhelming exposure, a lack of cross protection against non-Newport serotypes, and insufficient duration of immunity relative to harvest.