Competitive Exclusion of Intra-Genus Salmonella in Neonatal Broilers

Abstract

Salmonellosis is a zoonotic infection caused by Salmonella enterica serotypes contracted from contaminated products. We hypothesized that competitive exclusion between Salmonella serotypes in neonatal broilers would reduce colonization and affect the host immune response. Day of hatch broilers were randomly allocated to one of six treatment groups: (1) control, which received saline, (2) Salmonella Kentucky (SK) only on day 1 (D1), (3) Salmonella Typhimurium (ST) or Salmonella Enteritidis (SE) only on D1, (4) SK on D1 then ST or SE on day 2 (D2), (5) ST or SE on D1 then SK on D2, and (6) SK and ST or SE concurrently on D1. Salmonella gut colonization and incidence were measured from cecal contents. Livers and spleens were combined and macerated to determine systemic translocation. Relative mRNA levels of interleukin-1β (IL-1β), IL-6, IL-10, IL-18, and gamma interferon (IFN-γ) were measured in cecal tonsils and liver to investigate local and systemic immune responses. When a serotype was administered first, it was able to significantly reduce colonization of the following serotype. Significant changes were found in mRNA expression of cytokines. These results suggest competitive exclusion by Salmonella enterica serotypes affect local and systemic immune responses.

Serum cytokine profile of neonatal broiler chickens infected with Salmonella Typhimurium

“…However, many experiments in poultry focus on mRNA levels (Shebl et al, 2010). For example, our study differs from Pineda et al's study, where no significant differences in IL-6 or IFNγ mRNA expression were observed in the broiler cecal tonsils or liver when inoculated with SK, ST, and SE (Pineda et al, 2021). However, our data correlates to Kaiser and associates in vitro study, when specifically looking at IL-6 (Kaiser et al, 2000).…”

“…There are more than 2,600 Salmonella enterica serovars, but less than 100 of these serovars are known to cause human salmonellosis (USDA-FSIS, 2021). Salmonella Typhimurium (ST), S. Enteritidis (SE), and S. Kentucky (SK) are the three most common isolates found in contaminated poultry products (Van Immerseel et al, 2005;Kumar et al, 2019;Pineda et al, 2021). Poultry infected with paratyphoid Salmonella are OPEN ACCESS EDITED BY typically asymptomatic but can continually shed into the environment causing cross-contamination of carcasses and morbidity in humans (USDA-FSIS, 2021).…”

Nontyphoidal Salmonella infections acquired from poultry

“…There are several main pathogenicity islands reported for different serovars, with some being specific to certain serovars, but SPI-1 to SPI-5 are the most commonly present in serovars. As many of the mechanisms of colonization continue to be investigated, more recent studies have begun to explore intragenus competitive exclusion of Salmonella serovars, and how local and systemic immune responses are affected [10 ▪ ]. Continued studies will be useful to determine candidate serovars for sub-unit vaccine development as novel interventions for Salmonella control remain.…”

Gene expression of pro-inflammatory (IL-8, IL-18, TNF-α, and IFN-γ) and anti-inflammatory (IL-10) cytokines in the duodenum of broiler chickens exposed to lipopolysaccharides from Escherichia coli and Bacillus subtilis

“…Bacterial infections cause inflammatory processes that can cause alterations within the digestive system. One of the most efficient intestinal defense mechanisms is the production of pro-inflammatory cytokines [ 1 , 2 ], such as interleukin (IL)-1 and IL-6, and chemokines, such as IL-8, interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α), and IL-4 [ 3 ]. In this way, they collaborate with correct intestinal immunity against the microbial population [ 4 ].…”