Clostridium perfringens (Cp) is a Gram-positive anaerobe that is one of the causative agents of necrotic enteritis (NE) in chickens, which leads to high mortality. Owing to the ban of administering antibiotics in feed to chickens, there has been an increase in the number of NE outbreaks all over the world, and the estimated loss is approximately 6 billion U.S. dollars. The best alternative method to control NE without antibiotics could be vaccination. In this study, we exposed three different strains of Cp to electron beam (eBeam) irradiation to inactivate them and then used them as a killed vaccine to control the colonization of Cp in broiler chickens. The vaccine was delivered to 18-day old embryos in ovo and the chickens were challenged with the respective vaccine strain at two different time points (early and late) to test the protective efficacy of the vaccine. The results indicate that an effective eBeam dose of 10 kGy inactivated all three strains of Cp, did not affect the cell membrane or epitopes, induced significant levels of IgY in the vaccinated birds, and further reduced the colonization of Cp strains significantly (p < 0.0001) in late challenge (JGS4064: 4 out of 10; JGS1473: 0 out of 10; JGS4104: 3 out of 10). Further studies are necessary to enhance the efficacy of the vaccine and to understand the mechanism of vaccine protection.

The gut of food-producing animals is a reservoir for foodborne pathogens. Thymol is bactericidal against foodborne pathogens but rapid absorption of thymol from the proximal gut precludes the delivery of effective concentrations to the lower gut where pathogens mainly colonize. Thymol-β-d-glucopyranoside is reported to be more resistant to absorption than thymol in everted jejunal segments and could potentially function as a prebiotic by resisting degradation and absorption in the proximal gut but being hydrolysable by microbial β-glycosidase in the distal gut. Previous in vitro studies showed bactericidal effects of thymol-β-d-glucopyranoside against Campylobacter, Escherichia coli, and Salmonella enterica serovar Typhimurium in the presence but not absence of intestinal microbes expressing β-glycosidase activity, indicating that hydrolysis was required to obtain antimicrobial activity. Presently, the oral administration of thymol-β-d-glucopyranoside was studied to examine the effects on intestinal carriage of Campylobacter, E. coli, and S. Typhimurium in swine. The effects of thymol-β-d-glucopyranoside or thymol on antimicrobial sensitivity of representative E. coli isolates and characterized Salmonella strains were also explored. Results from two in vivo studies revealed little antimicrobial effects of thymol-β-d-glucopyranoside on Campylobacter, E. coli, or S. Typhimurium in swine gut. These findings add credence to current thinking that hydrolysis and absorption of thymol-β-d-glucopyranoside and thymol may be sufficiently rapid within the proximal gut to preclude delivery to the distal gut. Antibiotic susceptibilities of selected bacterial isolates and strains were mainly unaffected by thymol. Further research is warranted to overcome obstacles, preventing the delivery of efficacious amounts of thymol-β-d-glucopyranoside to the lower gut.

Salmonella Heidelberg (SH) on contaminated poultry causes economic and health risks to producers and consumers. We hypothesized that sodium bisulfate (SBS) would decrease SH biofilm on polyvinyl chloride (PVC) coupons and decrease the horizontal transfer of SH in broilers. Experiment 1: Salmonella Heidelberg biofilm was cultured with PVC coupons, which were treated with SBS at a pH of 3.5 for 10 min, 8 h, and 24 h. Experiment 2: Nine replicate pens per treatment were divided between two rooms. A seeder contact model was used to mimic a natural infection environment. Treatments consisted of tap water or sodium bisulfate in water at a pH of 3.5. Salmonella Heidelberg incidence and enumeration were measured in crops and ceca. Sodium bisulfate significantly reduced biofilm by 2.16 and 1.04 logs when treated for 8 and 24 h, respectively. Crop colonization was significantly decreased in trials 1 and 2 by 0.29 and 0.23 logs, respectively. Crop pH was significantly decreased in trial 2. Ceca colonization was significantly decreased in trial 1 by 0.39 logs. The results from the present study suggest that SBS may be administered to drinking water to decrease SH gut colonization and to reduce biofilm.

Numerous Salmonella enterica serovars can cause disease and contamination of animal-produced foods. Oligosaccharide-rich products capable of blocking pathogen adherence to intestinal mucosa are attractive alternatives to antibiotics as these have potential to prevent enteric infections. Presently, a wood-derived prebiotic composed mainly of glucose-galactose-mannose-xylose oligomers was found to inhibit mannose-sensitive binding of select Salmonella Typhimurium and Escherichia coli strains when reacted with Saccharomyces boulardii. Tests for the ability of the prebiotic to prevent binding of a green fluorescent protein (GFP)-labeled S. Typhimurium to intestinal porcine epithelial cells (IPEC-J2) cultured in vitro revealed that prebiotic-exposed GFP-labeled S. Typhimurium bound > 30% fewer individual IPEC-J2 cells than did GFP-labeled S. Typhimurium having no prebiotic exposure. Quantitatively, 90% fewer prebiotic-exposed GFP-labeled S. Typhimurium cells were bound per individual IPEC-J2 cell compared to non-prebiotic exposed GFP-labeled S. Typhimurium. Comparison of invasiveness of S. Typhimurium DT104 against IPEC-J2 cells revealed greater than a 90% decrease in intracellular recovery of prebiotic-exposed S. Typhimurium DT104 compared to non-exposed controls (averaging 4.4 ± 0.2 log₁₀ CFU/well). These results suggest compounds within the wood-derived prebiotic bound to E. coli and S. Typhimurium-produced adhesions and in the case of S. Typhimurium, this adhesion-binding activity inhibited the binding and invasion of IPEC-J2 cells.

Salmonella enterica is a group of facultative, gram-negative bacteria. Recently, new evidence indicated that Salmonella could reprogram the host metabolism to increase energy or metabolites available for intracellular replication. In this study, using a chicken-specific kinomic immunometabolism peptide array analysis, we found that infection by S. Enteritidis induced significant phosphorylation changes in many key proteins of the glycolytic pathway in chicken macrophage HD-11 cells, indicating a shift in glycolysis caused by Salmonella infection. Nitric oxide production and changes of glycolysis and mitochondrial oxidative phosphorylation (OXPHOS) represented by extracellular acidification rate (ECAR) and oxygen consumption rate (OCR), respectively, were measured in chicken macrophages infected with three Salmonella strains (S. Enteritidis, S. Heidelberg, and S. Senftenberg). The infection reduced glycolysis and enhanced OXPHOS in chicken macrophages as indicated by changes of ECAR and OCR. Salmonella strains differentially affected macrophage polarization and glycolysis. Among three strains tested, S. Enteritidis was most effective in downregulating glycolysis and promoting M2 polarization as measured by ECAR, ORC, and NO production; while S. Senftenberg did not alter glycolysis and may promote M1 polarization. Our results suggested that downregulation of host cell glycolysis and increase of M2 polarization of macrophages may contribute to increased intracellular survival of S. Enteritidis.