Emerging Strategies against Non-Typhoidal Salmonella: From Pathogenesis to Treatment

Even with the intensive efforts by public health programs to control and prevent it, non-typhoidal Salmonella (NTS) infection remains an important public health challenge. It is responsible for approximately 150 million illnesses and 60,000 deaths worldwide annually. NTS infection poses significant risks with high rates of morbidity and mortality, leading to potential short- and long-term complications. There is growing concern among health authorities about the increasing incidence of antimicrobial resistance, with multidrug resistance totaling 22.6% in Europe, highlighting an urgent need for new therapeutic approaches. Our review aims to provide a comprehensive overview of NTS infection. We outline the molecular mechanisms involved in the pathogenesis of NTS infection, as well as the events leading to invasive NTS infection and the subsequent complications associated with it. Given the widespread implications of antimicrobial resistance, our review also presents the global landscape of resistance, including multidrug resistance, and delve into the underlying mechanisms driving this resistance. The rising rates of antibiotic resistance frequently lead to treatment failures, emphasizing the importance of investigating alternative therapeutic options. Therefore, in this review we also explore potential alternative therapies that could offer promising approaches to treating NTS infections.

Combination of autochthonous Lactobacillus strains and trans-Cinnamaldehyde in water reduces Salmonella Heidelberg in turkey poults

Reducing the colonization of Salmonella in turkeys is critical to mitigating the risk of its contamination at later stages of production. Given the increased susceptibility of newly hatched poults to Salmonella colonization, it is crucial to implement interventions that target potential transmission routes, including drinking water. As no individual intervention explored to date is known to eliminate Salmonella, the United States Department of Agriculture-Food Safety Inspection Service (USDA-FSIS) recommends employing multiple hurdles to achieve a more meaningful reduction and minimize the potential emergence of resistance. Probiotics and plant-derived antimicrobials (PDAs) have demonstrated efficacy as interventions against Salmonella in poultry. Therefore, this study aimed to investigate the use of turkey-derived Lactobacillus probiotics (LB; a mixture of Lactobacillus salivarius UMNPBX2 and L. ingluviei UMNPBX19 isolated from turkey ileum) and a PDA, trans-cinnamaldehyde (TC), alone and in combination (CO), against S. Heidelberg in turkey drinking water and poults. The presence of 5% nutrient broth or cecal contents as contaminants in water resulted in S. Heidelberg growth. TC eliminated S. Heidelberg, regardless of the contaminants present. In contrast, the cecal contents led to increased survival of Lactobacillus in the CO group. Unlike TC, LB was most effective against S. Heidelberg when the nutrient broth was present, suggesting the role of secondary metabolites in its mechanism of action. In the experiments with poults, individual TC and LB supplementation reduced cecal S. Heidelberg in challenged poults by 1.2- and 1.7-log10 colony-forming units (CFU)/g cecal contents, respectively. Their combination yielded an additive effect, reducing S. Heidelberg by 2.7 log10 CFU/g of cecal contents compared to the control (p ≤ 0.05). However, the impact of TC and LB on the translocation of S. Heidelberg to the liver was more significant than CO. TC and LB are effective preharvest interventions against S. Heidelberg in poultry production. Nonetheless, further investigations are needed to determine the optimum application method and its efficacy in adult turkeys.

Synergistic influence of probiotic and florfenicol on embryonic viability, performance, and multidrug-resistant Salmonella Enteritidis in broiler chickens

This study was conducted during the period of August 2021 to April 2022 and divided into two parts. The first part involved the isolation and characterization of Salmonella from 200 diseased broiler chickens collected from farms in Dakahlia Governorate, Egypt, with the detection of its antimicrobial susceptibility. The second experimental part involved in ovo inoculation of probiotics and florfenicol to evaluate their effects on hatchability, embryonic viability, growth performance traits and the control of multidrug-resistant Salmonella Enteritidis infections post hatching. The point prevalence of Salmonella in the internal organs of diseased chickens was 13% (26/200), including 6 serotypes: S. Enteritidis, S. Typhimurium, S. Santiago, S. Colindale, S. Takoradi and S. Daula. Multidrug resistance was found in 92% (24/26) of the isolated strains with a multiantibiotic resistance index of 0.33-0.88 and 24 antibiotic resistance patterns. The in ovo inoculation of probiotic with florfenicol showed significant improvement in the growth performance parameters compared with other groups and had the ability to prevent colonization of multidrug resistant S. Enteritidis in the majority of the experimental chicks, and the remaining chicks showed very low colonization, as detected by RT‒PCR. These findings suggested the application of in ovo inoculation techniques with both probiotics and florfenicol as a promising tool to control multidrug-resistant S. Enteritidis in poultry farms.

Heat, cold, acid, and bile salt induced differential proteomic responses of a novel potential probiotic Lactococcus garvieae C47 isolated from camel milk

Probiotics encounter various stresses during food processing and digestion. This study evaluated the differential proteomic responses of a newly identified potential probiotic lactic acid bacteria, Lactococcus garvieae, isolated from camel milk. Lc. garvieae C47 was exposed to heat, cold, acid, and bile conditions, and stress-responsive proteins were identified. The proteomic analysis was done using 2D-IEF SDS PAGE and nano-LC-MS/MS. Out of 91 differentially expressed proteins, 20 upregulated and 27 downregulated proteins were shared among the stresses. The multivariate data analysis revealed abundance of elongation factor Ts (spot C42), uridine phosphorylase, fructose-bisphosphate aldolase, peptidase T, cobalt ECF transporter T component CbiQ, UDP-N-acetylmuramate-l-alanine ligase, uncharacterized protein, aspartokinase, chaperone protein DnaK, IGP synthase cyclase subunit, probable nicotinate-nucleotide adenylyltransferase, NADH-quinone oxidoreductase, holo-[acyl-carrier-protein] synthase, l-lactate dehydrogenase, and uncharacterized protein. The maximum number of differentially expressed proteins belonged to carbohydrate and protein metabolism, which indicates Lc. garvieae shifts towards growth and energy metabolism for resistance against stress conditions.

Lactobacillus in Food Animal Production—A Forerunner for Clean Label Prospects in Animal-Derived Products

Lactobacillus, the largest genus within the lactic acid bacteria group, has served diverse roles in improving the quality of foods for centuries. The heterogeneity within this genus has resulted in the industry's continued use of their well-known functions and exploration of novel applications. Moreover, the perceived health benefits in many applications have also made them fond favorites of consumers and researchers alike. Their familiarity lends to their utility in the growing “clean label” movement, of which consumers prefer fewer additions to the food label and opt for recognizable and naturally-derived substances. Our review primarily focuses on the historical use of lactobacilli for their antimicrobial functionality in improving preharvest safety, a critical step to validate their role as biocontrol agents and antibiotic alternatives in food animal production. We also explore their potential as candidates catering to the consumer-driven demand for more authentic, transparent, and socially responsible labeling of animal products.

Probiotics, Prebiotics, and Phytogenic Substances for Optimizing Gut Health in Poultry

The gut microbiota has been designated as a hidden metabolic ‘organ’ because of its enormous impact on host metabolism, physiology, nutrition, and immune function. The connection between the intestinal microbiota and their respective host animals is dynamic and, in general, mutually beneficial. This complicated interaction is seen as a determinant of health and disease; thus, intestinal dysbiosis is linked with several metabolic diseases. Therefore, tractable strategies targeting the regulation of intestinal microbiota can control several diseases that are closely related to inflammatory and metabolic disorders. As a result, animal health and performance are improved. One of these strategies is related to dietary supplementation with prebiotics, probiotics, and phytogenic substances. These supplements exert their effects indirectly through manipulation of gut microbiota quality and improvement in intestinal epithelial barrier. Several phytogenic substances, such as berberine, resveratrol, curcumin, carvacrol, thymol, isoflavones and hydrolyzed fibers, have been identified as potential supplements that may also act as welcome means to reduce the usage of antibiotics in feedstock, including poultry farming, through manipulation of the gut microbiome. In addition, these compounds may improve the integrity of tight junctions by controlling tight junction-related proteins and inflammatory signaling pathways in the host animals. In this review, we discuss the role of probiotics, prebiotics, and phytogenic substances in optimizing gut function in poultry.

Probiotic Lactobacilli Do Not Protect Chickens against Salmonella Enteritidis Infection by Competitive Exclusion in the Intestinal Tract but in Feed, Outside the Chicken Host

Lactobacilli are commonly used as probiotics in poultry to improve production parameters and to increase chicken resistance to enteric infections. However, lactobacilli do not efficiently colonise the chicken intestinal tract, and also, their anti-infection effect in vivo is sometimes questionable. In this study, we therefore evaluated the potential of a mixture of four Lactobacillus species (L. salivarius, L. reuteri, L. ingluviei and L. alvi) for the protection of chickens against Salmonella Enteritidis infection. Whenever the chickens were inoculated by lactobacilli and S. Enteritidis separately, there was no protective effect of lactobacilli. This means that when lactobacilli and S. Enteritidis are exposed to each other as late as in the crop of chickens, lactobacilli did not influence chicken resistance to S. Enteritidis at all. The only positive effect was recorded when the mixture of lactobacilli and S. Enteritidis was used for the inoculation of feed and the feed was anaerobically fermented for 1 to 5 days. In this case, chickens fed such a diet remained S. Enteritidis negative. In vitro experiments showed that the protective effect was caused by acidification of feed down to pH 4.6 due to lactobacilli fermentation and was associated with S. Enteritidis inactivation. The probiotic effect of lactobacilli was thus expressed in the feed, outside the chicken host.

The Microbiota-Gut-Brain Axis During Heat Stress in Chickens: A Review

Heat stress is a global issue for the poultry industries with substantial annual economic losses and threats to bird health and welfare. When chickens are exposed to high ambient temperatures, like other species they undergo multiple physiological alterations, including behavioral changes, such as cessation of feeding, initiation of a stress signaling cascade, and intestinal immune, and inflammatory responses. The brain and gut are connected and participate in bidirectional communication via the nervous and humoral systems, this network collectively known as the gut-brain axis. Moreover, heat stress not only induces hyperthermia and oxidative stress at the gut epithelium, leading to impaired permeability and then susceptibility to infection and inflammation, but also alters the composition and abundance of the microbiome. The gut microflora, primarily via bacterially derived metabolites and hormones and neurotransmitters, also communicate via similar pathways to regulate host metabolic homeostasis, health, and behavior. Thus, it stands to reason that reshaping the composition of the gut microbiota will impact intestinal health and modulate host brain circuits via multiple reinforcing and complementary mechanisms. In this review, we describe the structure and function of the microbiota-gut-brain axis, with an emphasis on physiological changes that occur in heat-stressed poultry.

Effects of the Probiotic Candidate E. faecalis-1, the Poulvac E. coli Vaccine, and their Combination on Growth Performance, Caecal Microbial Composition, Immune Response, and Protection against E. coli O78 Challenge in Broiler Chickens

The present study was performed on 180-day-old commercial Cobb chicks to assess the effects of the probiotic candidate Enterococcus faecalis-1, the Poulvac Escherichia coli vaccine, and their combination on growth parameters, intestinal microbial composition, immune response, and protection against challenge with the avian pathogen E. coli O78. The experimental groups were as follows: G1, basal diet; G2, basal diet and challenge with O78 at 28 days of growth; G3, basal diet, vaccination with Poulvac (1 and 15 days), and challenge with O78 at 28 days of growth; G4, basal diet, E. faecalis-1 supplementation for the first 3 days of growth, and challenge with O78 at 28 days of growth; G5, basal diet, E. faecalis-1 supplementation for the first 3 days of growth, vaccination with Poulvac (1 and 15 days), and challenge with O78 at 28 days of growth; G6, basal diet and E. faecalis-1 supplementation for the first 3 days of growth. The results showed that E. faecalis-1 in drinking water significantly improved the growth performance and immune response, increased the total Enterococcus counts, reduced the mortality, and decreased the visceral invasion by O78 in challenged broilers. While the effect of the Poulvac vaccine alone or with E. faecalis-1 was not significant compared with that of the E. faecalis-1 supplement, the vaccine improved the growth rate and decreased the mortality and visceral invasion by APEC O78 in challenged broilers. These results showed that E. faecalis-1 supplementation and routine vaccination with the Poulvac vaccine could improve the growth performance and immune response of broiler chickens and protect against challenge with APEC O78.

Probiotics and gut health: linking gut homeostasis and poultry productivity

The use of probiotics in poultry production has increased rapidly, and this movement has been promoted by global events, such as the prohibition or decline in the use of antibiotic growth promotants in poultry feeds. There has been a persistent search for alternative feed additives, and probiotics have shown that they can restore the composition of the gut microbiota, and produce health benefits to the host, including improvements in performance. Probiotics have shown potential to increase productivity in poultry, especially in flocks challenged by stressors. However, the outcomes of probiotic use have not always been consistent. There is an increasing demand for well defined products that can be applied strategically, and currently, probiotic research is focusing on delineating their mechanisms of action in the gut that contribute to an improved efficacy. In particular, mechanisms involved in the maintenance and protection of intestinal barrier integrity and the role of the gut microbiota are being extensively investigated. It has been shown that probiotics modulate intestinal immune pathways both directly and through interactions with the gut microbiota. These interactions are key to maintaining gut homeostasis and function, and improving feed efficiency. Research has demonstrated that probiotics execute their effects through multiple mechanisms. The present review describes recent advances in probiotic use in poultry. It focuses on the current understanding of gut homeostasis and gut health in chickens, and how it can be assessed and improved through supplementation of poultry diets with probiotics in poultry diets. In particular, cellular and molecular mechanisms involved in the maintenance and protection of gut barrier structure and function are described. It also highlights important factors that influence probiotic efficacy and bird performance.

Heat stress on microbiota composition, barrier integrity, and nutrient transport in gut, production performance, and its amelioration in farm animals

Livestock species experience several stresses, particularly weaning, transportation, overproduction, crowding, temperature, and diseases in their life. Heat stress (HS) is one of the most stressors, which is encountered in livestock production systems throughout the world, especially in the tropical regions and is likely to be intensified due to global rise in environmental temperature. The gut has emerged as one of the major target organs affected by HS. The alpha- and beta-diversity of gut microbiota composition are altered due to heat exposure to animals with greater colonization of pathogenic microbiota groups. HS also induces several changes in the gut including damages of microstructures of the mucosal epithelia, increased oxidative insults, reduced immunity, and increased permeability of the gut to toxins and pathogens. Vulnerability of the intestinal barrier integrity leads to invasion of pathogenic microbes and translocation of antigens to the blood circulations, which ultimately may cause systematic inflammations and immune responses. Moreover, digestion of nutrients in the guts may be impaired due to reduced enzymatic activity in the digesta, reduced surface areas for absorption and injury to the mucosal structure and altered expressions of the nutrient transport proteins and genes. The systematic hormonal changes due to HS along with alterations in immune and inflammatory responses often cause reduced feed intake and production performance in livestock and poultry. The altered microbiome likely orchestrates to the hosts for various relevant biological phenomena occurring in the body, but the exact mechanisms how functional communications occur between the microbiota and HS responses are yet to be elucidated. This review aims to discuss the effects of HS on microbiota composition, mucosal structure, oxidant-antioxidant balance mechanism, immunity, and barrier integrity in the gut, and production performance of farm animals along with the dietary ameliorations of HS. Also, this review attempts to explain the mechanisms how these biological responses are affected by HS.

Isolation of multidrug-resistant Escherichia coli from turkeys in Dinajpur, Bangladesh, and their antibiogram profile

OBJECTIVE

The study was carried out for molecular characterization and antibiotic resistance analysis of Escherichia coli isolated from different turkey farms in Dinajpur, Bangladesh.

MATERIALS AND METHODS

A total of 45 samples comprising feces (n = 23) and cloacal swabs (n = 22) were collected randomly from turkeys. The samples were subjected to isolation and identification of E. coli by cultural and biochemical characteristics, followed by polymerase chain reaction and sequencing. An antibiogram of the isolated E. coli isolates was carried out by following the Kirby-Bauer disk diffusion method.

RESULTS

Out of the 45 samples, 28 (62.21%) were positive for E. coli, of which 16 (35.55%) fecal samples were positive and 12 (26.66%) cloacal swabs were positive. The antibiotic sensitivity analysis revealed that all the E. coli isolates were 100% sensitive to levofloxacin, norfloxacin, neomycin, gentamicin, and nitrofurantoin. On the other hand, all the isolates were 100% resistant to amoxicillin, azithromycin, erythromycin, tetracycline, bacitracin, cephalexin, nalidixic acid, vancomycin, methicilin, piperacillin, pefloxacin, novobiocin, cefepime, trimethoprim, netilmicin, and aztreonam.

CONCLUSION

This study's results uncover the occurrence and antibiotic resistance pattern of E. coli in the study area's turkeys.

Prevalence, Concentration, and Antimicrobial Resistance Profiles of Salmonella Isolated from Florida Poultry Litter

ABSTRACT

For over a decade, Salmonella contamination has increasingly led to outbreaks of foodborne illness associated with fresh produce. The use of untreated animal manures, or biological soil amendments of animal origin, to amend agricultural soils holds a risk of contamination from foodborne pathogens, such as Salmonella. This study was conducted to determine the prevalence, concentration, serotypes, and antimicrobial resistance profiles of Salmonella in poultry litter from Florida farms. Litter pH, total Kjeldahl nitrogen, total ammonia nitrogen, total phosphorus (P2O5), total potassium (K2O), moisture content, total solids, total ash, organic matter, and aerobic plate count (APC) were also measured. Litter samples (n = 54) were collected from 18 broiler farms across three seasons (spring, summer, and winter). Salmonella concentrations were enumerated using a most-probable-number (MPN) method, and antimicrobial susceptibility testing was performed. The prevalence of Salmonella in litter samples was 61.1%, with a geometric mean of 0.21 ± 20.7 MPN/g. Across all seasons, Salmonella concentrations were not influenced by the chemical, physical, or microbial properties measured. Recovered Salmonella isolates (n = 290) were grouped into serogroups O:4 (43.1%), O:7 (26.9%), O:8 (11.0%), O:1,3,10,19 (7.9%), and O:9,46 (7.2%). Serotyping Salmonella isolates (n = 47) resulted in 12 serotypes, with the most common being Typhimurium (27.7%), Kentucky (17.0%), Enteritidis (14.9%), and Mbandaka (14.9%). Antimicrobial resistance to tetracycline (29.8%), sulfisoxazole (23.4%), and streptomycin (14.9%) was observed. No isolates were resistant to more than two antimicrobial agents. This study provides valuable information for future risk assessments for the use of poultry litter as an untreated biological soil amendment of animal origin.

HIGHLIGHTS

Effect of supplementation of a dairy-originated probiotic bacterium, Propionibacterium freudenreichii subsp. freudenreichii, on the cecal microbiome of turkeys challenged with multidrug-resistant Salmonella Heidelberg

A dairy-originated probiotic bacterium, Propionibacterium freudenreichii subsp. freudenreichii B3523 (PF) was found to be effective in reducing multidrug-resistant Salmonella Heidelberg (MDR SH) colonization in turkey poults (2-week-old) and growing (7-week-old) and finishing (12-week-old) turkeys. In this study, we explored the potential for microbiome modulation in the cecum of turkeys of different age groups due to PF supplementation in conjunction with MDR SH challenge. One-day-old commercial turkey poults were allocated to 3 treatment groups: negative control (N; turkeys without PF supplementation or SH challenge), SH control (S; turkeys challenged with SH without PF supplementation), and test group (P; turkeys supplemented with PF and challenged with SH). Turkeys were supplemented with 10¹⁰ CFU PF in 5-gallon (18.9 L) water until 7 or 12 week of age. At the 6th or 11^th wk, turkeys were challenged with SH at 10⁶ and 10⁸ CFU/bird by crop gavage, respectively. After 2 and 7 d of challenge (2-d postinoculation [PI] and 7-d PI, respectively), cecal samples were collected and microbiome analysis was conducted using Illumina MiSeq. The experiments were repeated twice with 8 and 10 turkeys/group for 7- and 12-wk studies, respectively. Results indicated that the species richness and abundance (Shannon diversity index) was similar among the treatment groups. However, treatments caused apparent clustering of the samples among each other (P < 0.05). Firmicutes was the predominant phylum in the growing and finishing turkey cecum which was evenly distributed among the treatments except on wk 12 where the relative abundance of Firmicutes was significantly higher in P than in N (P = 0.02). The MDR SH challenge resulted in modulation of microflora such as Streptococcus, Gordonibacter, and Turicibacter (P < 0.05) in the S groups compared with the P and N groups, known to be associated with inflammatory responses in birds and mammals. The supplementation of PF increased the relative abundance of carbohydrate-fermenting and short-chain fatty acid–producing genera in the P group compared with the S group (P < 0.05). Moreover, the results revealed that PF supplementation potentially modulated the beneficial microbiota in the P group, which could mitigate SH carriage in turkeys.

Metagenomic analysis reveals linkages between cecal microbiota and feed efficiency in Xiayan chickens

The cecal microbiota plays a critical role in energy harvest and nutrient digestion, influencing intestinal health and the performance of chickens. Feed efficiency (FE) is essential for improving economic efficiency and saving social resources in chicken production and may be affected by the cecal microbiota. Therefore, to investigate the composition and functional capacity of cecum microbes related to FE in Xiayan chicken, an indigenous breed in Guangxi province, metagenome sequencing was performed on chicken cecal contents. 173 male and 167 female chickens were divided into high and low FE groups according to the residual feed intake. The cecal microbial genome was extracted and sequenced. The results showed that the genera Bacteroides, Prevotella, and Alistipes were the 3 most abundant in each cecal microbiome. The linear discriminant analysis effect size revealed 6 potential biomarkers in male and 14 in female chickens. Notably, the relative abundance of Lactobacillus in the high FE group was higher than that of the low FE group both in the male and female chickens, and the species Limosilactobacillus oris has a higher score in the high FE group of male chickens. In contrast, some potentially pathogenic microorganisms such as Campylobacter avium in females and Helicobacter pullorum in males were enriched in the low FE group. Predictive functional analysis showed that the high FE group in male chickens had a greater ability of xenobiotics biodegradation and metabolism and signaling molecules and interaction. In addition, the host sex was found to exert effects on the cecal microbial composition and function associated with FE. These results increased our understanding of the cecal microbial composition and identified many potential biomarkers related to FE, which may be used to improve the FE of the chickens.

Changes in the cecal microbiota of laying hens during heat stress is mainly associated with reduced feed intake

The aim of the present study was to examine the effect of high temperature on the cecal microbiota of laying hens and analyze the correlation between variation in feed intake, body temperature, and the relative abundance of specific bacterial genera. Two hundred and sixteen 28-wk-old Hy-Line laying hens were randomly divided into 3 groups with 6 replicates and raised in 3 controlled climate chambers. Birds were allocated to either a thermoneutral group (TC, 21 ± 1°C, ad libitum), high cyclic temperature group (HT, 29-35°C, ad libitum), or a pair-feeding group (PF, 21 ± 1°C, pair-feeding on the daily feed intake of HT hens) for 4 wk. There was no significant difference in diversity estimators of laying hens between the HT and TC or PF groups (P > 0.05). Principal component analysis (PCoA) based on unweighted UniFrac distance showed that the HT group did not form a distinct cluster that was clearly separated from the PF group, but was separated from the TC group. Similarity analysis (ANOSIM) confirmed that the TC group was significantly different from the HT (R = 0.259, P = 0.020) and the PF (R = 0.348, P = 0.011) groups, but the HT group was similar with the PF group (R = 0.107, P = 0.153). In addition, there was a significant correlation between feed intake and principal coordinate 1 (PC1) in PCoA (R = -0.494, P = 0.037), but no correlation between core temperature and PC1 (R = 0.025, P = 0.923). Linear discriminant analysis identified 15 genera that discriminated between the HT and TC groups (score ≥2). Among these, the feed intake was significantly related with the relative abundance of 10 genera, however, the core temperature was only significantly correlated with one specific genus. In conclusion, a high cyclic temperature of 29-35°C had significant effects on microbial composition and structure of laying hens, which was mainly related with decreased feed intake.

Evaluation of the impact of in ovo administered bacteria on microbiome of chicks through 10 days of age

Initial inoculation and colonization of the chicken gastrointestinal tract (GIT) by microbiota have been suggested to have a major influence on the growth performance and health of birds. Commercial practices in chicken production may alter or delay microbial colonization by pioneer colonizing bacteria that can have an impact on the development and maturation of the GIT and intestinal microflora. The objective of this study was to compare the impact of apathogenic Gram-negative isolates or lactic acid bacteria (LAB) as pioneer colonizers on the microbiome at the day of hatch (DOH) and evaluate the influence through 10 D of age on ceca. At 18 embryonic days (E), the amnion of embryos was inoculated with either saline (S), approximately 102 CFU of LAB (L), Citrobacter freundii (C), or Citrobacter species (C2). Once DNA was isolated from mucosal and digesta contents, samples underwent 2 × 300 paired-end Illumina MiSeq library preparation for microbiome analysis. An increased abundance of Lactobacillaceae family and Lactobacillus genus was observed in the L group at DOH (P < 0.05), whereas the abundance of Enterococcaceae and Enterococcus was numerically decreased. While Lactobacillus salivarius was one of the pioneer colonizers in the L group at 18E, the population decreased by 10 D (39.59 to 0.09%) and replaced with a population of undefined Lactobacillus (10.36%) and Lactobacillus reuteri (3.63%). Results suggest that L treatment may have accelerated a mature microbiota. Enterobacteriaceae was the dominant family (57.44%) in C group at DOH (P < 0.05). The C2 group only showed some abundance of the C2 species (7.92%) at DOH but had the highest overall abundance of undefined Lactobacillus in the ceca by 10 D (25.28%). Taken together, different isolates provided in ovo can have an impact on the initial microbiome of the GIT, and some of these differences in ceca remain notable at 10 D.

Growth performance and gastrointestinal responses in heavy Tom turkeys fed antibiotic free corn-soybean meal diets supplemented with multiple doses of a single strain Bacillus subtilis probiotic (DSM29784)1

Growth performance and gastrointestinal (GIT) responses to a single-strain of Bacillus subtilis (SSB) were investigated using 960 Hybrid Converter Toms. A total of 4 iso-caloric and iso-nitrogenous corn-soybean meal-based diets were allocated to 12 replicate cages/pens and fed (ad libitum) in a four-phase feeding program (starter; days 0 to 28, grower-1; days 29 to 56, grower-2; days 57 to 84, and finisher; days 85 to 126). The diets had either 0 (control), 1E+08 (low), 2E+08 (mid) or 1E+09 (high) cfu B. subtilis/kg. Feed intake (FI) and BW were recorded by phase. Excreta samples were collected towards the end of starter and grower-1 phases for apparent retention (AR) of components by marker method and litter moisture, respectively. Selected birds were necropsied on days 28 and 56 for GIT weight and samples for jejunal histomorphology and ceca digesta short chain fatty acids (SCFA). Supplemental SSB had linear and non-linear (P < 0.05) response on BW gain (BWG). Specifically, relative to the control, birds fed low SSB had higher BWG in starter and grower-1 phases whereas bird fed mid and high SSB had lower BWG in grower-2 and birds fed low and mid SSB had higher BWG in finisher phase. Consequently, birds fed low and mid SSB doses were heavier (P < 0.05) than control fed birds at the end of trial. The FCR response to SSB was linear and non-linear (P < 0.05) with birds fed low SSB showing lower FCR than control fed birds in starter, grower-1 and finisher phases. Supplemental SSB had linear and non-linear (P < 0.05) effects on AR of components (DM, ash, crude protein, crude fat, neutral detergent fiber, and gross energy), litter moisture, GIT weight, jejunal histomorphology, and SCFA. Relative to control, birds fed high SSB showed higher AR of components, villi height, day 56 ceca digesta total SCFA concentration, and lower litter moisture. In conclusions, under condition of the current study, growth performance was optimized by low to mid SSB. Improved nutrient retention and indices of gut health suggested higher SSB doses may optimize growth performance under challenging farm conditions.

Isolation and Identification of Lactic Acid Bacteria Probiotic Culture Candidates for the Treatment of Salmonella enterica Serovar Enteritidis in Neonatal Turkey Poults

The effect of Lactobacillus spp.-based probiotic candidates on Salmonella enterica serovar Enteritidis (SE) colonization was evaluated in two separate experiments. In each experiment, sixty-one day-of-hatch female turkey poults were obtained from a local hatchery. In both experiments, poults were challenged via oral gavage with 10⁴ cfu/poult of SE and randomly allocated to one of two groups (n = 30 poults): (1) the positive control group and (2) the probiotic treated group. Heated brooder batteries were used for housing each group separately and poults were allowed ad libitum access to water and unmedicated turkey starter feed. 1 h following the SE challenge, poults were treated with 10⁶ cfu/poult of probiotic culture via oral gavage or phosphate-buffered saline （PBS）to control groups. A total of 24 h post-treatment, poults were euthanized and the ceca and cecal tonsils from twenty poults were collected aseptically for SE recovery. In both trials, a significant reduction in the incidence and log₁₀ cfu/g of SE were observed in poults treated with the probiotic when compared with control poults (p ≤ 0.05). The results of the present study suggest that the administration of this lactic acid-producing bacteria (LAB)-based probiotic 1 h after an SE challenge can be useful in reducing the cecal colonization of this pathogen in neonatal poults.

Probiotics and plant-derived compounds as eco-friendly agents to inhibit microbial toxins in poultry feed: a comprehensive review

Some of pathogenic bacteria and fungi have the ability to produce fetal toxins which may be the direct causes of cytotoxicity or cellular dysfunction in the colonization site. Biological and non-biological environmental factors, challenge and microbes influence the effect of toxins on these pathogens. Modern research mentions that many natural materials can reduce the production of toxins in pathogenic microbes. However, researches that explain the mechanical theories of their effects are meager. This review aimed to discuss the ameliorative potential role of plant-derived compounds and probiotics to reduce the toxin production of food-borne microbes either in poultry bodies or poultry feedstuff. Moreover, studies that highlight their own toxicological mechanisms have been discussed. Adding natural additives to feed has a clear positive effect on the enzymatic and microbiological appearance of the small intestine without any adverse effect on the liver. Studies in this respect were proposed to clarify the effects of these natural additives for feed. In conclusion, it could be suggested that the incorporation of probiotics, herbal extracts, and herbs in the poultry diets has some beneficial effects on productive performance, without a positive impact on economic efficiency. In addition, the use of these natural additives in feed has a useful impact on the microbiological appearance of the small intestine and do not have any adverse impacts on intestinal absorption or liver activity as evidenced by histological examination.

Antibiotic-Resistant Salmonella in the Food Supply and the Potential Role of Antibiotic Alternatives for Control

Salmonella enterica is one of the most ubiquitous enteropathogenic bacterial species on earth, and comprises more than 2500 serovars. Widely known for causing non-typhoidal foodborne infections (95%), and enteric (typhoid) fever in humans, Salmonella colonizes almost all warm- and cold-blooded animals, in addition to its extra-animal environmental strongholds. The last few decades have witnessed the emergence of highly virulent and antibiotic-resistant Salmonella, causing greater morbidity and mortality in humans. The emergence of several Salmonella serotypes resistant to multiple antibiotics in food animals underscores a significant food safety hazard. In this review, we discuss the various antibiotic-resistant Salmonella serotypes in food animals and the food supply, factors that contributed to their emergence, their antibiotic resistance mechanisms, the public health implications of their spread through the food supply, and the potential antibiotic alternatives for controlling them.

Effects of Pediococcus acidilactici, mannan-oligosaccharide, butyric acid and their combination on growth performance and intestinal health in young broiler chickens challenged with Salmonella Typhimurium

This study compared the efficacy of Pediococcus acidilactici, mannan-oligosaccharide, butyric acid, and their combination on growth performance and intestinal health in broiler chickens challenged with S. Typhimurium. Ross 308 male broilers (n = 420) were randomly assigned to one of the 6 treatments, resulting in 5 replicate pens of 14 chicks per treatment. The treatments included a negative control [(NC), no additive, not challenged]; positive control [(PC), no additive, but challenged with S. Typhimurium at d 3 posthatch], and 4 groups whereby birds were challenged with S. Typhimurium at d 3 posthatch and fed diets supplemented with either probiotic [0.1 g/kg Pediococcus acidilactici (PA)], prebiotic [2 g/kg mannan-oligosaccharides (MOS)], organic acid [0.5 g/kg butyric acid (BA)], or a combination of the 3 additives (MA). The S. Typhimurium challenge decreased feed intake, body weight gain and increased feed conversion ratio and reduced jejunum villus height (VH) and VH to crypt depth (CD) ratio (P < 0.05). Birds on the MA treatment exhibited similar performance to birds on the NC treatment (P > 0.05) and had a lower population of Salmonella in the ceca compared with birds on the PC treatment, at d 14 and 21 post-challenge (P < 0.05). The lowest heterophil to lymphocyte ratio was observed in birds on the MA and NC treatments (P < 0.05). Birds fed diets supplemented with MA or PA had greater VH and VH: CD ratio than birds on the PC treatment at d 7, 14 and 21 d post-challenge (P < 0.05). Suppressed amylase and protease activity was observed as a result of the S. Typhimurium challenge; the enzyme levels were restored in birds fed the additive-supplemented diets, when compared to the birds on the PC treatment, particularly at d 21 post-challenge (P < 0.05). These results indicate that dietary supplementation with a combination of PA, BA, and MOS in broiler chickens could be used as an effective tool for controlling S. Typhimurium and promoting growth performance.

Salmonella infection - prevention and treatment by antibiotics and probiotic yeasts: a review

Global Salmonella infection, especially in developing countries, is a health and economic burden. The use of antibiotic drugs in treating the infection is proving less effective due to the alarming rise of antibiotic-resistant strains of Salmonella, the effects of antibiotics on normal gut microflora and antibiotic-associated diarrhoea, all of which bring a growing need for alternative treatments, including the use of probiotic micro-organisms. However, there are issues with probiotics, including their potential to be opportunistic pathogens and antibiotic-resistant carriers, and their antibiotic susceptibility if used as complementary therapy. Clinical trials, animal trials and in vitro investigations into the prophylactic and therapeutic efficacies of probiotics have demonstrated antagonistic properties against Salmonella and other enteropathogenic bacteria. Nonetheless, there is a need for further studies into the potential mechanisms, efficacy and mode of delivery of yeast probiotics in Salmonella infections. This review discusses Salmonella infections and treatment using antibiotics and probiotics.

Dietary Lactobacillus acidophilus positively influences growth performance, gut morphology, and gut microbiology in rurally reared chickens

In a market undergoing constant evolution, the production of chicken meat that consumers would perceive as “natural” and “animal friendly” is crucial. The use of probiotics in rurally reared chickens could represent a major opportunity to achieve mutual benefit for both the industry and consumers. A total of 264 male Kabir chicks were randomly distributed to one of 2 dietary treatments: the L group received a commercial feed supplemented with 2.0 g/100 kg of Lactobacillus acidophilus D2/CSL, while the C group received the same basal diet without the additive. To assess the effects of probiotic supplementation in the chickens’ diet, productive performance was evaluated at d 21 and 42, whereas microbiological analyses of the intestinal content and intestinal histology and morphometry were performed at the end of the trial (d 42). At d 21 and 42, L birds showed better (P < 0.001) performance in terms of body weight, average daily gain, and feed conversion ratio. Enterococci, staphylococci, and Escherichia coli populations were not influenced by dietary treatment. On the contrary, Lactobacillus population increased (P = 0.032) in the L group. Furthermore, a tendency (P = 0.069) was observed for the coliforms to be influenced by diet, with lower values in the L group in comparison to the C group. Histological techniques revealed that the number of goblet cell containing neutral mucins was lower in the C group. Morphometric evaluations demonstrated that the probiotic supplementation increased the height of the mucosal layer by improving (P = 0.040) villus height, while crypt depth was unaffected. In conclusion, the results obtained in this study demonstrate that it is possible to use Lactobacillus acidophilus D2/CSL (CECT 4529) in rurally reared chicken breeds with positive effects on performance and gut health.

Evaluation of a Solid Dispersion of Curcumin With Polyvinylpyrrolidone and Boric Acid Against Salmonella Enteritidis Infection and Intestinal Permeability in Broiler Chickens: A Pilot Study

In the present study, in vitro assays were conducted to evaluate the solubility of curcumin (CUR) alone or with polyvinylpyrrolidone (PVP) at different pH, as well as its permeability in Caco-2 cells. Results confirmed that the solid dispersion of CUR with PVP (CUR/PVP) at a 1:9 ratio, significantly increased (P < 0.05) solubility and permeability compared to CUR alone. Then, the antimicrobial activity of CUR/PVP, boric acid (BA), and a combination of 0.5% CUR/PVP and 0.5% BA (CUR/PVP-BA) against Salmonella Enteritidis (SE) was determined using an in vitro digestion model that simulates crop, proventriculus, and intestine. The results revealed that in the proventriculus and intestinal compartments significant reductions of SE were observed in all the experimental treatments, but 1% BA eliminated SE in the intestinal compartment and CUR/PVP-BA showed a synergistic effect on antimicrobial activity against SE. To complement these findings, two independent in vivo trials were conducted to determine the effect of 0.1% CUR/PVP; 0.1% BA; or the combination of 0.05% CUR/PVP (1:9 ratio) and 0.05% BA (CUR/PVP-BA) on the antimicrobial activity against SE, intestinal permeability and inflammatory responses in broiler chickens. BA at 0.1% had no significant in vivo effects against SE. However, the combination of 0.05% BA and 0.05% CUR/PVP and 0.05% BA was sufficient to reduce crop and intestinal SE colonization in broiler chickens in two independent trials, confirming the synergic effect between them. A similar antimicrobial impact against SE intestinal colonization was observed in chickens treated with 0.1% CUR/PVP at a 1:9 ratio, which could be due to the increase in solubility of CUR by PVP. Furthermore, 0.1% CUR/PVP reduced the intestinal permeability of FITC-d and total intestinal IgA, as well as increase the activity of SOD when compared to control, while, CUR/PVP-BA only decreased SOD activity. Further studies to confirm and expand the in vivo results obtained in this pilot study, adding intestinal microbial commensal groups and more inflammatory biomarkers to get a complete description of the effects of BA and CUR deserves further investigation.

Effect of Various Inoculum Levels of Multidrug-Resistant Salmonella enterica Serovar Heidelberg (2011 Ground Turkey Outbreak Isolate) on Cecal Colonization, Dissemination to Internal Organs, and Deposition in Skeletal Muscles of Commercial Turkeys after Experimental Oral Challenge

Salmonella enterica serovar Heidelberg (S. Heidelberg) is a major foodborne pathogen colonizing poultry. The pathogen is associated with a significant number of foodborne outbreaks through contaminated poultry meat, including turkeys. Recently, multidrug-resistant (MDR) strains of S. Heidelberg have emerged as a threat to human public health in the United States. The objective of this study was to determine the cecal colonization, dissemination to internal organs, and the potential for skeletal muscle deposition of an MDR S. Heidelberg isolate from the 2011 ground turkey outbreak in the United States after the experimental oral challenge of poults (young turkeys) and adult turkey hens. In the poult study, two separate experiments using day-old, straight-run, commercial hybrid converter poults were randomly assigned to five challenge groups (0, 10∧2, 10∧4, 10∧6, 10∧8 CFU groups; 12 poults/group; N = 60/experiment) and a week after, treatment groups were challenged separately with 0-, 2-, 4-, 6-, and 8- log10 CFU of S. Heidelberg orally. After 14 days post-challenge, the poults were euthanized, and samples were collected to determine MDR S. Heidelberg colonization in the cecum, dissemination to liver and spleen, and deposition in the thigh, drumstick, and breast muscles. A similar experimental design was followed for the adult turkey hens. In two separate experiments, 11-week-old commercial Hybrid Converter turkey hens (4 hens/group; N = 20/experiment) were challenged with MDR S. Heidelberg and on day 16 post-challenge, birds were euthanized and samples were collected to determine Salmonella populations in the samples. The results indicated that, in turkey poults, the recovery of MDR S. Heidelberg was highest in the cecum followed by spleen, liver, thigh, drumstick, and breast. All tested inoculum levels resulted in more than 3.5 log10 CFU/g colonization in the poult cecum. The cecal colonization, dissemination to internal organs, and tissue deposition of MDR S. Heidelberg were high in poults. The pathogen recovery from the cecum of adult turkey hens ranged from 37.5 to 62.5% in the challenge groups. The results signify the importance of controlling MDR S. Heidelberg in turkeys at the farm level to improve the safety of turkey products.

Characterization of a Multidrug-Resistant Salmonella enterica Serovar Heidelberg Outbreak Strain in Commercial Turkeys: Colonization, Transmission, and Host Transcriptional Response

In recent years, multidrug-resistant (MDR) Salmonella enterica serovar Heidelberg (S. Heidelberg) has been associated with numerous human foodborne illness outbreaks due to consumption of poultry. For example, in 2011, an MDR S. Heidelberg outbreak associated with ground turkey sickened 136 individuals and resulted in 1 death. In response to this outbreak, 36 million pounds of ground turkey were recalled, one of the largest meat recalls in U.S. history. To investigate colonization of turkeys with an MDR S. Heidelberg strain isolated from the ground turkey outbreak, two turkey trials were performed. In experiment 1, 3-week-old turkeys were inoculated with 10⁸ or 10¹⁰ CFU of the MDR S. Heidelberg isolate, and fecal shedding and tissue colonization were detected following colonization for up to 14 days. Turkey gene expression in response to S. Heidelberg exposure revealed 18 genes that were differentially expressed at 2 days following inoculation compared to pre-inoculation. In a second trial, 1-day-old poults were inoculated with 10⁴ CFU of MDR S. Heidelberg to monitor transmission of Salmonella from inoculated poults (index group) to naive penmates (sentinel group). The transmission of MDR S. Heidelberg from index to sentinel poults was efficient with cecum colonization increasing 2 Log10 CFU above the inoculum dose at 9 days post-inoculation. This differed from the 3-week-old poults inoculated with 10¹⁰ CFU of MDR S. Heidelberg in experiment 1 as Salmonella fecal shedding and tissue colonization decreased over the 14-day period compared to the inoculum dose. These data suggest that young poults are susceptible to colonization by MDR S. Heidelberg, and interventions must target turkeys when they are most vulnerable to prevent Salmonella colonization and transmission in the flock. Together, the data support the growing body of literature indicating that Salmonella establishes a commensal-like condition in livestock and poultry, contributing to the asymptomatic carrier status of the human foodborne pathogen in our animal food supply.

Current Status of the Preharvest Application of Pro- and Prebiotics to Farm Animals to Enhance the Microbial Safety of Animal Products

The selection of microorganisms that act as probiotics and feed additives that act as prebiotics is an ongoing research effort, but a sizable range of commercial pro-, pre- and synbiotic (combining pro- and prebiotics) products are already available and being used on farms. A survey of the composition of commercial products available in the United States revealed that Lactobacillus acidophilus, Enterococcus faecium, and Bacillus subtilis were the three most common species in probiotic products. Of the nearly 130 probiotic products (also called direct-fed microbials) for which information was available, about 50 also contained yeasts or molds. The focus on these particular bacteria and eukaryotes is due to long-standing ideas about the benefits of such strains, research data on effectiveness primarily in laboratory or research farm settings, and regulations that dictate which microorganisms or feed additives can be administered to farm animals. Of the direct-fed microbials, only six made a claim relating to food safety or competitive exclusion of pathogens. None of the approximately 50 prebiotic products mentioned food safety in their descriptions. The remainder emphasized enhancement of animal performance such as weight gain or overall animal health. The reason why so few products carry food safety-related claims is the difficulties in establishing unambiguous cause and effect relationships between the application of such products in varied and constantly changing farm environments and improved food safety of the end product.

Fermented rapeseed meal is effective in controlling Salmonella enterica serovar Typhimurium infection and improving growth performance in broiler chicks

The aim of present experiment was to assess the effects of fermented rapeseed meal (FRSM) on Salmonella enterica serovar Typhimurium (S. Typhimurium) colonization and growth performance in broiler chicks. Two hundred forty day-old male Cobb 500 broiler chicks were divided into six experimental treatments with four replicates and 10 birds per each. The treatments were including two positive and negative controls which birds received a basal corn-soybean diet as well as four others which birds received the diets that rapeseed meal (RSM) or FRSM was replaced with soybean meal at 50 and 100% levels. All chicks except the negative control birds were challenged orally with 10⁵ CFU of S. Typhimurium at 3days of age. Results showed that birds were fed FRSM had significantly greater lactic acid bacteria populations and lesser S. Typhimurium colonization in ileal and cecal sections compared to others (P<0.05). The less percentage of liver and bursa of fabricius was belonged to negative control group. At 10day, feeding chicks with diet containing FRSM, but not RSM, significantly decreased the organ invasion by S. Typhimurium (P<0.05). Heterophil to lymphocyte ratio was significantly lesser in chicks were fed FRSM compared to those fed RSM or positive control (P<0.05). Birds were fed FRSM had significantly higher weight gain and better feed conversion ratio compared to those birds were fed RSM (P<0.05). The findings of present experiment concerning positive effects of feeding FRSM on reducing S. Typhimurium and improving growth performance show that this processed protein source can be considered as a nutritional effective strategy to control Salmonella contamination in broiler chicks.

Evaluation of a selected lactic acid bacteria-based probiotic on Salmonella enterica serovar Enteritidis colonization and intestinal permeability in broiler chickens

Two experiments were conducted to evaluate the effect of a lactic acid bacteria-based probiotic (FloraMax-B11^®) against Salmonella enterica serovar Enteritidis intestinal colonization and intestinal permeability in broiler chickens. Experiment 1 consisted of two independent trials. In each trial, day-old broiler chicks were assigned to one of two groups: control + S. Enteritidis or probiotic + S. Enteritidis. At 72 h post-S. Enteritidis challenge, haematology and caecal content were evaluated for S. Enteritidis colonization. In Experiment 2, day-old broiler chicks were assigned to one of four groups: negative control; probiotic; control + S. Enteritidis; or probiotic + S. Enteritidis. At 72 h post-S. Enteritidis challenge, chickens in all groups were given an oral gavage dose of fluorescein isothiocyanate dextran (FITC-d). In both trials of Experiment 1, a significant reduction (P < 0.05) in colony-forming units/gram of S. Enteritidis in caecal content and a reduction in the incidence of S. Enteritidis enriched caecal samples were observed in probiotic + S. Enteritidis chickens. In addition, significant heterophilia and lymphopaenia were observed in control + S. Enteritidis chickens. In Experiment 2, a decrease in numbers of S. Enteritidis in caeca were observed in probiotic + S. Enteritidis chickens when compared to control + S. Enteritidis. Also, an increase in serum FITC-d concentration was detected in control + S. Enteritidis. These results suggest that early infection with S. Enteritidis can increase intestinal permeability, but the adverse effects can be prevented by the administration of the probiotic tested.

Risks Involved in the Use of Enrofloxacin for Salmonella Enteritidis or Salmonella Heidelberg in Commercial Poultry

The objectives of the present study were to evaluate the risks involved in the use of Enrofloxacin for Salmonella Enteritidis (SE) or Salmonella Heidelberg (SH) in commercial poultry and determine the effects of a probiotic as an antibiotic alternative. Two experiments were conducted to evaluate the risks involved in the use of Enrofloxacin for SE or SH in commercial poultry. Experiment 1 consisted of two trials. In each trial, chickens were assigned to one of three groups; control + SE challenged; Enrofloxacin 25 mg/kg + SE; and Enrofloxacin 50 mg/kg + SE. Chickens received Enrofloxacin in the drinking water from days 1 to 5 of age. On day 6, all groups received fresh water without any treatment. All chickens were orally gavaged with 10⁷ cfu/chick of SE at 7 days of age and euthanized on 8 days of age. In Experiment 2, turkey poults were assigned to one of the three groups; control + SH; probiotic + SH; and Enrofloxacin 50 mg/kg + SH. Poults received probiotic or Enrofloxacin in the drinking water from days 1 to 5 of age. On day 6, poults received fresh water without any treatment. Poults were orally gavaged with 10⁷ cfu/poult of SH at 7 days of age. Poults were weighed and humanely killed 24 h post-SH challenge to evaluate serum concentration of fluorescein isothiocyanate-dextran to evaluate intestinal permeability, metagenomics, and SH infection. In both trials of Experiment 1, chickens treated with Enrofloxacin were more susceptible to SE organ invasion and intestinal colonization when compared with control non-treated chickens (P < 0.05). In Experiment 2, poults treated with 50 mg/kg of Enrofloxacin showed an increase in body weight, however, this group also showed an increase in SH susceptibility, intestinal permeability, and lower proportion of Firmicutes and Bacteroidetes, but with control group had the highest proportion of Proteobacteria. By contrast, poults that received the probiotic had the highest proportion of Firmicutes and Bacteroidetes, but lowest Proteobacteria. The results of the present study suggest that prophylactic utilization of Enrofloxacin at five times the recommended dose in poultry increases the susceptibility to salmonellae infections, and confirms that probiotics may be an effective tool in salmonellae infections.

Use of the potential probiotic strain Lactobacillus salivarius SMXD51 to control Campylobacter jejuni in broilers

Campylobacteriosis is the most frequently reported zoonotic disease in humans in the EU since 2005. As chicken meat is the main source of contamination, reducing the level of Campylobacter in broiler chicken will lower the risk to consumers. The aim of this project was to evaluate the ability of Lactobacillus salivarius SMXD51 to control Campylobacter jejuni in broilers and to investigate the mechanisms that could be involved. Thirty broilers artificially contaminated with C. jejuni were treated by oral gavage with MRS broth or a bacterial suspension (10⁷CFU) of Lb. salivarius SMXD51 (SMXD51) in MRS broth. At 14 and 35days of age, Campylobacter and Lb. salivarius loads were assessed in cecal contents. The impact of the treatment on the avian gut microbiota at day 35 was also evaluated. At day 14, the comparison between the control and treated groups showed a significant reduction (P<0.05) of 0.82 log. After 35days, a significant reduction (P<0.001) of 2.81 log in Campylobacter loads was observed and 73% of chickens treated with the culture exhibited Campylobacter loads below 7log₁₀CFU/g. Taxonomic analysis revealed that SMXD51 treatment induced significant changes (P<0.05) in a limited number of bacterial genera of the avian gut microbiota and partially limited the impact of Campylobacter on Anaerotruncus sp. decrease and Subdoligranulum sp. increase. Thus, SMXD51 exhibits an anti-Campylobacter activity in vivo and can partially prevent the impact of Campylobacter on the avian gut microbiota.

Effect of a potential probiotics Lactococcus garvieae B301 on the growth performance, immune parameters and caecum microflora of broiler chickens

In this study, a novel Lactococcus garvieae B301 was isolated from the intestinal tract of a healthy piglet. L. garvieae B301 was tolerant to acid pH, simulated gastric and small intestinal transit juices, indicating that it was capable of surviving in the gastrointestinal tract. L. garvieae B301 was safe and beneficial to broilers, as broiler chickens supplemented with L. garvieae B301 had lower diarrhoea incidence and mortality than the Control. Moreover, supplementation of broiler diets with L. garvieae B301 resulted in an increase in body weight and the number of caecum lactic acid bacteria and Bifidobacterium spp., and decrease in feed-to-gain ratio and the number of caecum coliforms. It also had a positive effect on the thymus index and bursa of Fabricius index and enhanced serum levels of immune globulins. All these results showed that L. garvieae B301 could enhance the growth performance of broiler chickens and improve their health. Thus, L. garvieae B301 could be a promising feed additive for broiler chickens.

Food-producing animals and their health in relation to human health

The fields of immunology, microbiology, and nutrition converge in an astonishing way. Dietary ingredients have a profound effect on the composition of the gut microflora, which in turn regulates the physiology of metazoans. As such, nutritional components of the diet are of critical importance not only for meeting the nutrient requirements of the host, but also for the microbiome. During their coevolution, bacterial microbiota has established multiple mechanisms to influence the eukaryotic host, generally in a beneficial fashion. The microbiome encrypts a variety of metabolic functions that complements the physiology of their hosts. Over a century ago Eli Metchnikoff proposed the revolutionary idea to consume viable bacteria to promote health by modulating the intestinal microflora. The idea is more applicable now than ever, since bacterial antimicrobial resistance has become a serious worldwide problem both in medical and agricultural fields. The impending ban of antibiotics in animal feed due to the current concern over the spread of antibiotic resistance genes makes a compelling case for the development of alternative prophylactics. Nutritional approaches to counteract the debilitating effects of stress and infection may provide producers with useful alternatives to antibiotics. Improving the disease resistance of animals grown without antibiotics will benefit the animals’ health, welfare, and production efficiency, and is also a key strategy in the effort to improve the microbiological safe status of animal-derived food products (e.g. by poultry, rabbits, ruminants, or pigs). This review presents some of the alternatives currently used in food-producing animals to influence their health in relation to human health.

Evaluation of germination, distribution, and persistence of Bacillus subtilis spores through the gastrointestinal tract of chickens

Spores are popular as direct-fed microbials, though little is known about their mode of action. Hence, the first objective of the present study was to evaluate the in vitro germination and growth rate of Bacillus subtilis spores. Approximately 90% of B. subtilis spores germinate within 60 min in the presence of feed in vitro. The second objective was to determine the distribution of these spores throughout different anatomical segments of the gastrointestinal tract (GIT) in a chicken model. For in vivo evaluation of persistence and dissemination, spores were administered to day-of-hatch broiler chicks either as a single gavage dose or constantly in the feed. During 2 independent experiments, chicks were housed in isolation chambers and fed sterile corn-soy-based diets. In these experiments one group of chickens was supplemented with 10(6) spores/g of feed, whereas a second group was gavaged with a single dose of 10(6) spores per chick on day of hatch. In both experiments, crop, ileum, and cecae were sampled from 5 chicks at 24, 48, 72, 96, and 120 h. Viable B. subtilis spores were determined by plate count method after heat treatment (75°C for 10 min). The number of recovered spores was constant through 120 h in each of the enteric regions from chickens receiving spores supplemented in the feed. However, the number of recovered B. subtilis spores was consistently about 10(5) spores per gram of digesta, which is about a 1-log10 reduction of the feed inclusion rate, suggesting approximately a 90% germination rate in the GIT when fed. On the other hand, recovered B. subtilis spores from chicks that received a single gavage dose decreased with time, with only approximately 10(2) spores per gram of sample by 120 h. This confirms that B. subtilis spores are transiently present in the GIT of chickens, but the persistence of vegetative cells is presently unknown. For persistent benefit, continuous administration of effective B. subtilis direct-fed microbials as vegetative cells or spores is advisable.

Yerba mate enhances probiotic bacteria growth in vitro but as a feed additive does not reduce Salmonella Enteritidis colonization in vivo

Yerba mate (Ilex paraguariensis) is a tea known to have beneficial effects on human health and antimicrobial activity against some foodborne pathogens. Thus, the application of yerba mate as a feed additive for broiler chickens to reduce Salmonella colonization was evaluated. The first in vitro evaluation was conducted by suspending Salmonella Enteritidis and lactic acid bacteria (LAB) in yerba mate extract. The in vivo evaluations were conducted using preventative and horizontal transmission experiments. In all experiments, day-of-hatch chicks were treated with one of the following 1) no treatment (control); 2) ground yerba mate in feed; 3) probiotic treatment (Lactobacillus acidophilus and Pediococcus; 9:1 administered once on day of hatch by gavage); or 4) both yerba mate and probiotic treatments. At d 3, all chicks were challenged with Salmonella Enteritidis (preventative experiment) or 5 of 20 chicks (horizontal transmission experiment). At d 10, all birds were euthanized, weighed, and cecal contents enumerated for Salmonella. For the in vitro evaluation, antimicrobial activity was observed against Salmonella and the same treatment enhanced growth of LAB. For in vivo evaluations, none of the yerba mate treatments significantly reduced Salmonella Enteritidis colonization, whereas the probiotic treatment significantly reduced Salmonella colonization in the horizontal transmission experiment. Yerba mate decreased chicken BW and decreased the performance of the probiotic treatment when used in combination. In conclusion, yerba mate had antimicrobial activity against foodborne pathogens and enhanced the growth of LAB in vitro, but in vivo yerba mate did not decrease Salmonella Enteritidis colonization.

Evaluation of effects of EarlyBird associated with FloraMax-B11 on Salmonella Enteritidis, intestinal morphology, and performance of broiler chickens

A posthatch fasting period of 24 to 72 h is a common and inevitable practice in commercial poultry production. This delay in start of feed intake has been reported to negatively affect yolk utilization, gastrointestinal development, slaughter weight, breast meat yield, performance, and to also depress immunological development, making the birds more susceptible to infection from pathogens such as Salmonella. Furthermore, public concerns regarding the considerable human rates of illness reported and the emergence of antibiotic-resistant strains of Salmonella have doubled the challenge on the poultry industry to find alternative means of Salmonella control. In the present study, we evaluated the effects of a combination of early feeding with probiotic supplementation on morphological development of mucosa, control of Salmonella, and overall performance in broiler chickens. We used a blend of a commercially available perinatal supplement, EarlyBird (EB; Pacific Vet Group USA Inc., Fayetteville, AR), and a successful probiotic supplement, FloraMax-B11 (FM; Pacific Vet Group USA Inc.), to evaluate the effects on gut morphology, Salmonella intestinal colonization, and horizontal transmission, along with its effects on BW and related performance in broiler chickens under simulated commercial hatching management and shipping conditions. Morphometric analysis showed increased villus height, villus width, villus to crypt ratio, and villus surface area index in chickens treated with EB + FM groups. Significant reductions in Salmonella recovery, incidence, and horizontal transmission were also observed among the same groups, suggesting beneficial effects of early feeding and competitive exclusion by probiotic bacteria. Improved gut morphology and Salmonella exclusion was very well supported by BW data with significantly lower early BW loss and overall BW gains in birds treated with EB + FM mixture. The results of this study demonstrated that the combination of EB and FM improved gut morphology, reduced the amount of Salmonella that could be recovered, as well as improved BW when compared with controls and each product individually. These data address both animal welfare and food safety concerns faced by the poultry industry.

Bioengineered probiotics, a strategic approach to control enteric infections

Enteric infections account for high morbidity and mortality and are considered to be the fifth leading cause of death at all ages worldwide. Seventy percent of all enteric infections are foodborne. Thus significant efforts have been directed toward the detection, control and prevention of foodborne diseases. Many antimicrobials including antibiotics have been used for their control and prevention. However, probiotics offer a potential alternative intervention strategy owing to their general health beneficial properties and inhibitory effects against foodborne pathogens. Often, antimicrobial probiotic action is non-specific and non-discriminatory or may be ineffective. In such cases, bioengineered probiotics expressing foreign gene products to achieve specific function is highly desirable. In this review we summarize the strategic development of recombinant bioengineered probiotics to control enteric infections, and to examine how scientific advancements in the human microbiome and their immunomodulatory effects help develop such novel and safe bioengineered probiotics.

Modern approaches in probiotics research to control foodborne pathogens

Foodborne illness is a serious public health concern. There are over 200 known microbial, chemical, and physical agents that are known to cause foodborne illness. Efforts are made for improved detection, control and prevention of foodborne pathogen in food, and pathogen associated diseases in the host. Several commonly used approaches to control foodborne pathogens include antibiotics, natural antimicrobials, bacteriophages, bacteriocins, ionizing radiations, and heat. In addition, probiotics offer a potential intervention strategy for the prevention and control of foodborne infections. This review focuses on the use of probiotics and bioengineered probiotics to control foodborne pathogens, their antimicrobial actions, and their delivery strategies. Although probiotics have been demonstrated to be effective in antagonizing foodborne pathogens, challenges exist in the characterization and elucidation of underlying molecular mechanisms of action and in the development of potential delivery strategies that could maintain the viability and functionality of the probiotic in the target organ.