Effect of dietary direct-fed microbial and yeast cell walls on cecal digesta microbiota of layer chicks inoculated with nalidixic acid resistant Salmonella Enteritidis

Effects of Salmonella Enteritidis infection on TLRs gene expression and microbial diversity in cecum of laying hens

Salmonella Enteritidis (SE) is an important foodborne pathogen primarily causing human disease through contaminated food and water. In the current study, to assess the effect of Salmonella Enteritidis infection on the immune system and the microbial diversity of cecum and oviduct in chickens, twelve 24-week-old SE-negative White Leghorn layers were randomly selected and divided into 2 groups. Chickens in the challenge group were orally inoculated with SE, and chickens in the control group received an equal amount of sterilized Phosphate Buffered Saline solution. Serum and tissue samples (cecum, oviduct, ovary, liver, spleen, and pancreas) were collected at 7 days and 14 days post-infection (dpi). Quantitative PCR was used to detect the expression of Toll-like receptors (TLRs) in the cecum, oviduct and ovary. To understand the influence of SE infection on the microbial profile of the cecum and oviduct, microbial community composition of the cecal contents and oviducal contents were analyzed through 16S rRNA sequencing. Results showed that SE infection caused damage to the digestive organs, reproductive organs, and immune organs in laying hens. The expression of TLR1a, TLR1b, TLR2, TLR4, TLR5, TLR7 and TLR15 in the cecum were induced, and the content of IFN-γ, TNF-α, IL-2 and IL-18 in serum increased after SE infection. The composition of the microbial community significantly changed in cecal content, the dominant phylum of Firmicutes increased, and Bacteroidetes decreased significantly. In the oviduct, the microbial diversity became complicated, the dominant bacteria Faecalibacterium was significantly increased, and Bacteroides was significantly decreased. This study investigated the effects of SE infection in laying hens, including host innate immunity, the expression of TLRs, and changes in the composition of microbes in the cecum and reproductive tract. Our results may provide a scientific basis for the Salmonella Enteritidis control in chicken, the maintenance of oviduct function, and the guarantee of clean egg production.

Effect of a Saccharomyces cerevisiae Postbiotic Feed Additive on Salmonella Enteritidis Colonization of Cecal and Ovarian Tissues in Directly Challenged and Horizontally Exposed Layer Pullets

Determining the efficacy of feed-additive technologies utilized as pre-harvest food-safety interventions against Salmonella enterica may be influenced by factors including, but not limited to, mechanism of action, experimental design variables, Salmonella serovar(s), exposure dose, route, or duration in both controlled research and real-world field observations. The purpose of this study was to evaluate the dietary inclusion of a Saccharomyces cerevisiae fermentation-derived postbiotic (SCFP) additive (Diamond V, Original XPC®) on the colonization of cecal and ovarian tissues of commercial pullets directly and indirectly exposed to Salmonella Enteritidis (SE). Four hundred and eighty commercial, day-of-age W-36 chicks were randomly allotted to 60 cages per treatment in two identical BSL-2 isolation rooms (Iowa State University) with four birds per cage and fed control (CON) or treatment (TRT) diets for the duration of study. At 16 weeks, two birds per cage were directly challenged via oral gavage with 1.1 × 109 CFU of a nalidixic-acid-resistant SE strain. The remaining two birds in each cage were thus horizontally exposed to the SE challenge. At 3, 7, and 14 days post-challenge (DPC), 20 cages per group were harvested and sampled for SE prevalence and load. No significant differences were observed between groups for SE prevalence in the ceca or ovary tissues of directly challenged birds. For the indirectly exposed cohort, SE cecal prevalence at 7 DPC was significantly lower for TRT (50.0%) vs. CON (72.5%) (p = 0.037) and, likewise, demonstrated significantly lower mean SE cecal load (1.69 Log10) vs. CON (2.83 Log10) (p = 0.005). At 14 DPC, no significant differences were detected but ~10% fewer birds remained positive in the TRT group vs. CON (p > 0.05). These findings suggest that diets supplemented with SCFP postbiotic may be a useful tool for mitigating SE colonization in horizontally exposed pullets and may support pre-harvest food-safety strategies.

Beneficial insights into postbiotics against colorectal cancer

Colorectal cancer (CRC) is one of the most prevalent and life-threatening cancer types with limited therapeutic options worldwide. Gut microbiota has been recognized as the pivotal determinant in maintaining gastrointestinal (GI) tract homeostasis, while dysbiosis of gut microbiota contributes to CRC development. Recently, the beneficial role of postbiotics, a new concept in describing microorganism derived substances, in CRC has been uncovered by various studies. However, a comprehensive characterization of the molecular identity, mechanism of action, or routes of administration of postbiotics, particularly their role in CRC, is still lacking. In this review, we outline the current state of research toward the beneficial effects of gut microbiota derived postbiotics against CRC, which will represent the key elements of future precision-medicine approaches in the development of novel therapeutic strategies targeting gut microbiota to improve treatment outcomes in CRC.

Non-Antibiotics Strategies to Control Salmonella Infection in Poultry

Salmonella spp. is a facultative intracellular pathogen causing localized or systemic infections, involving economic and public health significance, and remains the leading pathogen of food safety concern worldwide, with poultry being the primary transmission vector. Antibiotics have been the main strategy for Salmonella control for many years, which has allowed producers to improve the growth and health of food-producing animals. However, the utilization of antibiotics has been reconsidered since bacterial pathogens have established and shared a variety of antibiotic resistance mechanisms that can quickly increase within microbial communities. The use of alternatives to antibiotics has been recommended and successfully applied in many countries, leading to the core aim of this review, focused on (1) describing the importance of Salmonella infection in poultry and the effects associated with the use of antibiotics for disease control; (2) discussing the use of feeding-based (prebiotics, probiotics, bacterial subproducts, phytobiotics) and non-feeding-based (bacteriophages, in ovo injection, vaccines) strategies in poultry production for Salmonella control; and (3) exploring the use of complementary strategies, highlighting those based on -omics tools, to assess the effects of using the available antibiotic-free alternatives and their role in lowering dependency on the existing antimicrobial substances to manage bacterial infections in poultry effectively.