Competitive Exclusion of Intra-Genus Salmonella in Neonatal Broilers

Serum cytokine profile of neonatal broiler chickens infected with Salmonella Typhimurium

The avian immune system responds to Salmonella infection by expressing cytokines and chemokines. We hypothesized that the immune status of Salmonella Typhimurium (ST) challenged neonatal broilers would differ from the uninfected treatment. The objective of this experiment was to evaluate 12 cytokines. Day of hatch male chicks were randomly allocated into a control or ST challenged group. At day three of age, sterile diluent or 5.0 × 108 CFU of ST was given orally to each chick. Blood was obtained 24 h post challenge and serum separated for later analysis (n = 30 chicks/treatment). Significant (p ≤ 0.05) increases in pro-inflammatory cytokines-interleukin-6 (IL-6), IL-16, and IL-21; anti-inflammatory cytokines- IL-10; chemokines-regulated on activation, normal T cell expressed and secreted (RANTES), macrophage inflammatory protein-1β (MIP-1β), and MIP-3α; colony stimulating factors-macrophage colony-stimulating factor (M-CSF); and growth factors-vascular endothelial growth factor (VEGF) were observed in the serum of the challenged chicks when compared to the control. No significant differences were observed in IL-2, interferon gamma (IFNγ), and IFNα. These data indicate the detection of mucosal immune responses in broiler chickens following ST infection. The heightened levels of pro-inflammatory cytokines, chemokines, and colony stimulating factors align with known inflammatory mechanisms, like the influx of immune cells. However, the elevation of IL-10 was unexpected, due to its immunoregulatory properties. Notably, the rise in VEGF levels is compelling, as it suggests the possibility of tissue repair and angiogenesis in ST infected birds.

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

Background and Aim

Intestinal infections are associated with Gram-negative bacteria like Escherichia coli. When eliminated by treatments during replication, E. coli release lipopolysaccharides (LPS) that can activate the intestinal immune system and increase the expression of cytokines, such as interleukin (IL)-8, IL-18, tumor necrosis factor-alpha (TNF-α), and interferon-gamma (IFN-γ), by the intestinal epithelium under pathological conditions. This study aimed to evaluate the addition of Bacillus subtilis to the duodenal gene expression of pro-inflammatory and anti-inflammatory cytokines in broilers exposed to LPS from E. coli.

Materials and Methods

RNA was extracted using the Zymo Research total RNA commercial kit, according to the manufacturer's specifications, from the intestinal tissue of the duodenum previously resuspended in the lysis buffer of the kit. The expression of the cytokines of interest was measured using the QuantiNova SYBR green real-time polymerase chain reaction kit (Qiagen). Transcript quantification was performed by the ΔΔC(t) method using glyceraldehyde 3-phosphate dehydrogenase as a normalizing constitutive gene.

Results

For the measurement of pro-inflammatory (IL-8, IL-18, TNF-α, and IFN-γ) and anti-inflammatory (IL-10) cytokines, there was no statistically significant difference (p > 0.05) between the basal diet and the diet with antibiotic (avilamycin). There was a statistical difference (p < 0.05) between diets with LPS. The diet with B. subtilis presented the lowest expression; the results differed on each sampling day (days 14, 28, and 42).

Conclusion

A decrease in the expression of pro-inflammatory cytokines (IL-8, IL-18, TNF-α, and IFN-γ) and an increase in IL-10 (anti-inflammatory) was observed; in this way, a balance of the inflammatory response to bacterial infection is achieved, suggesting that the use of B. subtilis as an additive in a broiler diet has a similar effect to that produced with antibiotic growth promoter.

Nontyphoidal Salmonella infections acquired from poultry

PURPOSE OF REVIEW

Nontyphoidal Salmonella is a major food safety concern in developed and developing countries. Table eggs are often linked to cases of foodborne gastrointestinal disease. This review is focused on the latest findings on foodborne Salmonella infections acquired from poultry products and their implications on food safety.

RECENT FINDINGS

Salmonella Enteritidis (SE) and Salmonella Typhimurium (ST) are the predominant Salmonella serovars associated with human Salmonellosis. In Australia, ST is the predominant serovar but SE has been recently detected in some commercial free-range egg flocks. The Salmonella shedding in poultry flocks can be highly variable across different flocks and farms; as a result, the level of product contamination is largely attributed to the flock management. The microevolution in the ST genome after in-vivo passaging may have clinical significance. On farm use of Salmonella vaccines and/or interventions during the processing of the product can influence the bacterial load. The refrigeration of the product also influences the safety of the poultry product.

SUMMARY

Many interventions are in place for the control of Salmonella from farm to fork. However, given the biosecurity challenges because of the increase in public demand for free-range products, the emergence of Salmonella virulent types and expensive diagnostics, ongoing collaborative efforts from farmers, regulators and public health officials are required.