Preharvest Food Safety in Broiler Chicken Production

The probiotic Lacticaseibacillus rhamnosus GG supplementation reduces Salmonella load and modulates growth, intestinal morphology, gut microbiota, and immune responses in chickens

Salmonella, a leading cause of foodborne illnesses, is primarily transmitted to humans through the consumption of contaminated poultry products. The increasing resistance of Salmonella to antibiotics and lack of cross-protection by vaccines necessitate new control strategies in poultry production systems. This study assessed the efficacy of probiotics against Salmonella Typhimurium (ST) and Salmonella Enteritidis (SE). Lactobacillus acidophilus (LA), Lacticaseibacillus rhamnosus GG (LGG), and Bifidobacterium animalis subsp. lactis (Bb12) showed inhibition of ST and SE in agar well diffusion assay, with stable inhibitory properties. In co-culture assay, both LGG and Bb12 completely suppressed ST and SE growth. Liquid chromatography-with tandem mass spectrometry (LC-MS/MS) analysis of the LGG and Bb12 cell-free culture supernatant identified novel bioactive peptides with anti-Salmonella properties. Administering LGG in drinking water of chickens raised on built-up litter floor in experimental conditions significantly reduced the ST load (5.95 logs and 3.74 on 7 days post-infection [dpi] and 14 dpi, respectively). Gut microbiota analysis revealed increased abundance of several beneficial genera such as Butyricicoccus, Erysipelatoclostridium, Flavonifractor, and Bacillus in LGG-treated groups. Histomorphometry analysis demonstrated increased villus height (VH) and VH by crypt depth ratio in the ileum of the LGG-treated group on 14 dpi. These results highlight LGG as a promising probiotic for controlling Salmonella in chickens and reducing transmission to humans. The beneficial properties of LGG are attributed to the production of antimicrobial peptides, microbiota modulation, and enhanced intestinal integrity.IMPORTANCESalmonella is the leading cause of foodborne illnesses in the United States and worldwide. It is primarily transmitted through contaminated poultry and poultry products (eggs and poultry meat). Increasing resistance of Salmonella to antibiotics and lack of cross-protection by vaccines necessitate new control strategies to reduce Salmonella in poultry production system and minimize human infections. Probiotics, which are live beneficial microorganisms when administered in an optimum amount, have been increasingly used in recent years as alternatives to antibiotics to promote health. Our study showed that LGG exhibited superior probiotics properties and significantly reduced Salmonella load in chickens. Thus, LGG supplementation is a promising approach to prevent Salmonella infection and enhance performance of poultry thereby enhance food safety, proper antibiotic stewardship and public health.

A Mini-Review on Multi-Hurdle Control of Salmonella Along Poultry Production Continuum

This mini-review presents common strategies for controlling Salmonella in poultry, addressing combined pre-harvest and post-harvest interventions to create a multi-hurdle approach. The goal is to highlight integrated approaches that enhance overall food safety and sustainability within the poultry industry. Current pre-harvest and post-harvest strategies are discussed, including industry practices and regulatory frameworks. Emphasis is placed on the implementation of biosecurity measures, vaccination, feed management, and environmental control in pre-harvest settings, as well as processing plant interventions such as antimicrobials for carcass decontamination, sanitation, and quality control measures. Pre-harvest strategies that have shown promise include enhanced biosecurity protocols, selective vaccinations for pathogenic Salmonella strains, and advanced feeding regimens. Post-harvest interventions, such as antimicrobial application for decontamination, have improved sanitation practices, and pathogen reduction technologies are also critical in reducing Salmonella prevalence. An integrated approach that combines both pre-harvest and post-harvest measures is essential for an effective Salmonella control program. Implementing a continuum of control strategies for Salmonella in poultry production is vital for ensuring food safety and protecting public health. Collaborative efforts between researchers, industry stakeholders, and policymakers are necessary to address emerging issues and enhance overall effectiveness.

Probiotics in Poultry: Unlocking Productivity Through Microbiome Modulation and Gut Health

This review explores the role of probiotics in improving productivity and gut health in poultry through microbiome modulation, particularly during early life. Gut health is pivotal to poultry performance, influencing nutrient absorption, immune function, and disease resistance. Early-life interventions target the microbiome to shape long-term health and productivity. Probiotics, live microorganisms providing health benefits, improve gut health through the competitive exclusion of pathogens, immune modulation, antimicrobial compound production, and enhancing gut barrier integrity. Applying probiotics improves growth performance, feed conversion efficiency, body weight gain, and carcass quality by promoting lean muscle growth and reducing fat deposition. For laying hens, probiotics enhance egg production and quality. These benefits are linked to better nutrient utilization, a well-balanced microbiome, and reduced gastrointestinal disorders. However, the efficacy of probiotics depends on strain specificity, dosage, and administration methods. Factors like environmental conditions, storage stability, and interactions with other feed additives also influence their effectiveness. Despite these challenges, advancements in microbiome research and probiotic technologies, such as precision probiotics and synbiotics, provide promising solutions. Future research should focus on optimizing formulations, understanding host-microbiome interactions, and leveraging new technologies for targeted microbiome management.

Progress in the application of Salmonella vaccines in poultry: A mini review

Salmonella is a critical group of zoonotic pathogens that are widely spread in poultry, causing avian salmonellosis. This disease usually leads to significant reductions in poultry performance, including reduced egg production in laying hens, decreased hatchability in chicks, and retarded growth in broilers. As a result, worldwide poultry industry suffers serious economic losses. Vaccination serves as an essential strategy for preventing Salmonella infection in poultry, effectively reducing susceptibility and alleviating disease symptoms, while also minimizing fecal shedding and environmental contamination. This subsequently diminishes public health risks. Various Salmonella vaccines can induce humoral and cellular immune responses to different extents. Therefore, a thorough understanding of the immune defense mechanisms, especially adaptive immune responses in poultry infected with Salmonella, is crucial for the development of Salmonella vaccines. This review summarizes the progress in the application of Salmonella vaccines in poultry, including adaptive immune responses induced by Salmonella and vaccines targeting the predominant circulating serotypes in poultry. It also provides an insight into the future of poultry-origin Salmonella vaccines.

Systematic review on microbiome-related nutritional interventions interfering with the colonization of foodborne pathogens in broiler gut to prevent contamination of poultry meat

This systematic review aimed to compile the available body of knowledge about microbiome-related nutritional interventions contributing to improve the chicken health and having an impact on the reduction of colonization by foodborne pathogens in the gut. Original research articles published between 2012 and 2022 were systematically searched in Scopus and PubMed. A total of 1,948 articles were retrieved and 140 fulfilled the inclusion criteria. Overall, 73 papers described 99 interventions against colonization by Escherichia coli and related organisms; 10 papers described 15 interventions against Campylobacter spp.; 36 papers described 54 interventions against Salmonella; 40 papers described 54 interventions against Clostridium perfringens. A total of 197 microbiome-related interventions were identified as effective against one or more of the listed pathogens and included probiotics (n = 80), prebiotics (n = 23), phytobiotics (n = 25), synbiotics (n = 12), organic acids (n = 12), enzymes (n = 4), essential oils (n = 14) and combination of these (n = 27). The identified interventions were mostly administered in the feed (173/197) or through oral gavage (11/197), in the drinking water (7/197), in ovo (2/197), intra amniotic (2/197), in fresh or reused litter (1/197) or both in the feed and water (1/197). The interventions enhanced the beneficial microbial communities in the broiler gut as Lactic acid bacteria, mostly Lactobacillus spp., or modulated multiple microbial populations. The mechanisms promoting the fighting against colonization by foodborne pathogens included competitive exclusion, production of short chain fatty acids, decrease of gut pH, restoration of the microbiome after dysbiosis events, promotion of a more stable microbial ecology, expression of genes improving the integrity of intestinal mucosa, enhancing of mucin production and improvement of host immune response. All the studies extracted from the literature described in vivo trials but performed on a limited number of animals under experimental settings. Moreover, they detailed the effect of the intervention on the chicken gut without details on further impact on poultry meat safety.

Practical Preventive Considerations for Reducing the Public Health Burden of Poultry-Related Salmonellosis

With poultry products as one of the leading reservoirs for the pathogen, in a typical year in the United States, it is estimated that over one million individuals contract non-typhoidal Salmonella infections. Foodborne outbreaks associated with Salmonella infections in poultry, thus, continue to remain a significant risk to public health. Moreover, the further emergence of antimicrobial resistance among various serovars of Salmonella is an additional public health concern. Feeding-based strategies (such as use of prebiotics, probiotics, and/or phytobiotics as well as essential oils), non-feeding-based strategies (such as use of bacteriophages, vaccinations, and in ovo strategies), omics tools and surveillance for identifying antibiotic-resistance genes, post-harvest application of antimicrobials, and biosecurity measures at poultry facilities are practical interventions that could reduce the public health burden of salmonellosis and antibiotic resistance associated with poultry products. With the escalating consumption of poultry products around the globe, the fate, prevalence, and transmission of Salmonella in agricultural settings and various poultry-processing facilities are major public health challenges demanding integrated control measures throughout the food chain. Implementation of practical preventive measures discussed in the current study could appreciably reduce the public health burden of foodborne salmonellosis associated with poultry products.

Purified Plant-Derived Phenolic Acids Inhibit Salmonella Typhimurium without Alteration of Microbiota in a Simulated Chicken Cecum Condition

Salmonella enterica serovar Typhimurium (ST) remains a predominant zoonotic pathogen because of its colonization in poultry, survivability in the environment, and increasing antibiotic-resistance pattern. Plant-derived phenolics, gallic acid (GA), protocatechuic acid (PA), and vanillic acids (VA) have demonstrated antimicrobial activity in vitro; therefore, this study collected chicken cecal fluid and supplemented it with these phenolics to evaluate their potential for eliminating ST and mod-ulating the microbiota of complex environments. ST was quantified through plating, while micro-biome analysis was performed through pair-end 16S-rRNA gene sequencing. CFU/mL of ST in cecal fluid with GA was significantly reduced by 3.28 and 2.78 log at 24 h and 48 h, while PA only had a slight numerical decrease. VA significantly reduced ST by 4.81 and 5.20 log at 24 h and 48 h. Changes in relative abundance of major phyla were observed at 24 h for samples with GA and VA as Firmicute levels increased 8.30% and 20.90%, while Proteobacteria decreased 12.86% and 18.48%, respectively. Significant changes in major genre were observed in Acinetobacter (3.41% for GA) and Escherichia (13.53% for VA), while Bifidobacterium increased (3.44% for GA) and Lactobacillus remained unchanged. Results suggest that phenolic compounds exert different effects on certain pathogens, while supporting some commensal bacteria.

Antagonistic activity and mechanism of Lactobacillus rhamnosus SQ511 against Salmonella enteritidis

Salmonella enteritidis is an important food-borne pathogen. The use of antibiotics is a serious threat to animal and human health, owing to the existence of resistant strains and drug residues. Lactic acid bacteria, as a new alternative to antibiotics, has attracted much attention. In this study, we investigated the antibacterial potential and underlying mechanism of Lactobacillus rhamnosus SQ511 against S. enteritidis ATCC13076. The results revealed that L. rhamnosus SQ511 significantly inhibited S. enteritidis ATCC13076 growth or even caused death. Laser confocal microscopic imaging revealed that the cell-free supernatant (CFS) of L. rhamnosus SQ511 elevated the reactive oxygen species level and bacterial membrane depolarization in S. enteritidis ATCC13076, leading to cell death. Furthermore, L. rhamnosus SQ511 CFS had severely deleterious effects on S. enteritidis ATCC13076, causing membrane destruction and the release of cellular materials. In addition, L. rhamnosus SQ511 CFS significantly reduced the expression of virulence, motility, adhesion, and invasion genes in S. enteritidis ATCC13076 (P < 0.05), and considerably inhibited motility and biofilm formation capacity (P < 0.05). Thus, antimicrobial compounds produced by L. rhamnosus SQ511 strongly inhibited S. enteritidis growth, mobility, biofilm formation, membrane disruption, and reactive oxygen species generation, and regulated virulence-related gene expressions, presenting promising applications as a probiotic agent.

Efficacy of a Biocidal Paint in Controlling Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae) and Improving the Quality of Air and Litter in Poultry Houses

Effective disinfection and disinsection are the keys to successful operation of modern poultry farms and the safety of poultry products. The cleaning and disinfection of poultry houses are important aspects of farm hygiene management. The correct execution of all steps of cleaning, disinfection, and disinsection procedures and the use of appropriate products are crucial for the prevention and control of zoonotic and animal diseases. In this study it was assumed that a water-based slow-release biocidal paint could be useful in controlling insect pests such as Alphitobius diaperinus and reducing microbiological contamination of air and litter in poultry houses and have a beneficial effect on microclimate in poultry houses. Therefore, the locations of A. diaperinus in the poultry houses, the microbiological contamination of air and litter, as well as the microclimatic conditions in the houses and the physicochemical parameters of the litter were evaluated. The results suggest that the tested biocidal paint could be an effective alternative to other insecticides and disinfectants. Additionally, the research is of a practical nature and may be very useful for poultry producers in controlling A. diaperinus populations and maintaining proper hygiene in poultry houses. Further research is needed.

Intestinal Mucosal Immunity-Mediated Modulation of the Gut Microbiome by Oral Delivery of Enterococcus faecium Against Salmonella Enteritidis Pathogenesis in a Laying Hen Model

Enterococcus faecium (E. faecium) is a protective role that has crucial beneficial functions on intestinal homeostasis. This study aimed to investigate the effects of E. faecium on the laying performance, egg quality, host metabolism, intestinal mucosal immunity, and gut microbiota of laying hens under the Salmonella Enteritidis (S. Enteritidis) challenge. A total of 400 45-week-old laying hens were randomly divided into four treatments (CON, EF, SCON, and SEF groups) with five replicates for each group and 20 hens per replicate and fed with a basal diet or a basal diet supplemented with E. faecium (2.5 × 10⁸ cfu/g feed). The experiment comprised two phases, consisting of the pre-salmonella challenged phase (from day 14 to day 21) and the post-salmonella challenged phase (from day 21 to day 42). At day 21 and day 22, the hens in SCON and SEF groups were orally challenged with 1.0 ml suspension of 10⁹ cfu/ml S. Enteritidis (CVCC3377) daily, whereas the hens in CON and EF groups received the same volume of sterile PBS. Herein, our results showed that E. faecium administration significantly improved egg production and shell thickness during salmonella infection. Also, E. faecium affected host lipid metabolism parameters via downregulating the concentration of serum triglycerides, inhibited oxidative stress, and enhanced immune functions by downregulating the level of serum malondialdehyde and upregulating the level of serum immunoglobulin G. Of note, E. faecium supplementation dramatically alleviated intestinal villi structure injury and crypt atrophy, and improved intestinal mucosal barrier injuries caused by S. Enteritidis challenge. Moreover, our data revealed that E. faecium supplementation ameliorated S. Enteritidis infection-induced gut microbial dysbiosis by altering the gut microbial composition (reducing Bacteroides, Desulfovibrio, Synergistes, and Sutterella, and increasing Barnesiella, Butyricimonas, Bilophila, and Candidatus_Soleaferrea), and modulating the gut microbial function, such as cysteine and methionine metabolism, pyruvate metabolism, fatty acid metabolism, tryptophan metabolism, salmonella infection, and the PI3K-Akt signaling pathway. Taken together, E. faecium has a strong capacity to inhibit the S. Enteritidis colonization of hens. The results highlight the potential of E. faecium supplementation as a dietary supplement to combat S. Enteritidis infection in animal production and to promote food safety.

Occurrence, Risk Factors, Serotypes, and Antimicrobial Resistance of Salmonella Strains Isolated from Imported Fertile Hatching Eggs, Hatcheries, and Broiler Farms in Trinidad and Tobago

ABSTRACT

This cross-sectional study was conducted to determine the occurrence, risk factors, and characteristics of Salmonella isolates recovered from imported fertile broiler hatching eggs, hatcheries, and broiler farms in Trinidad and Tobago. Standard methods were used to isolate and characterize Salmonella isolates from two broiler hatcheries and 27 broiler farms in the country. The frequency of isolation of Salmonella was 0.0% for imported fertile hatching eggs (0 of 45 pools of 10 eggs each, i.e., 450 eggs), 7.6% for hatcheries (12 of 158 samples), and 2.8% for broiler farms (24 of 866 samples) (P = 0.006). Stillborn chicks at hatcheries had the highest prevalence of Salmonella (7 of 28 samples, 28.0%), whereas on broiler farms the cloacal swabs had the highest prevalence of Salmonella (15 of 675 samples, 2.2%). None of the 15 farm management and production practices investigated were significantly associated (P > 0.05) with the isolation of Salmonella. The predominant Salmonella serotypes were Kentucky (83.3%) and Infantis (62.5%) among hatchery and farm isolates, respectively. The disk diffusion method revealed frequencies of antimicrobial resistance (i.e., resistance to one or more agents) of 44.0% (11 of 25 isolates) and 87.5% (35 of 40 isolates) at hatcheries and broiler farms, respectively (P = 0.0002). Antimicrobial resistance among hatchery isolates was highest (28.0%) to doxycycline and kanamycin and was very high (>65%) among farm isolates to sulfamethoxazole-trimethoprim, gentamicin, ceftriaxone, kanamycin, and doxycycline. Multidrug resistance (MDR; i.e., resistance to antimicrobial agents from three or more classes) was exhibited by 4.0 and 85.7% of Salmonella isolates recovered from several environmental and animal sources at the hatcheries and farms, respectively (P < 0.0001). The high level of antimicrobial resistance and the presence of MDR among Salmonella isolates from broiler farms highlight the therapeutic implications and the potential for MDR strains to enter the food chain.

HIGHLIGHTS

Lactobacillus johnsonii 3-1 and Lactobacillus crispatus 7-4 promote the growth performance and ileum development and participate in lipid metabolism of broilers

Long-term use of antibiotic growth promoter (AGP) in animal production is the main cause of antimicrobial resistance of pathogenic bacteria. Therefore, seeking alternatives to AGP is crucial for animal husbandry. Among all AGP alternatives, probiotics are promising candidates. In this study, two strains of lactic acid bacteria, L. johnsonii 3-1 and L. crispatus 7-4, were isolated from the feces of wild Gallus gallus, which exhibited obvious anti-pathogenic activity and improved the growth performance of broilers. Furthermore, we found that these two strains participated in the lipid metabolism of broilers by reducing the content of TC and TG in ileal epithelial cells and up-regulating the liver AMPKα/PPARα/CPT-1 pathway, which affects abdominal fat deposition. In summary, L. johnsonii 3-1 and L. crispatus 7-4 have the potential to be used as AGP substitutes and participate in the lipid metabolism of broilers to reduce abdominal fat deposition. Importantly, our study reveals for the first time that L. crispatus participates in liver lipid metabolism to reduce abdominal fat deposition in broilers.

Multidrug Resistance Dynamics in Salmonella in Food Animals in the United States: An Analysis of Genomes from Public Databases

The number of bacterial genomes deposited each year in public databases is growing exponentially. However, efforts to use these genomes to track trends in antimicrobial resistance (AMR) have been limited thus far. We used 22,102 genomes from public databases to track AMR trends in nontyphoidal Salmonella in food animals in the United States. In 2018, genomes deposited in public databases carried genes conferring resistance, on average, to 2.08 antimicrobial classes in poultry, 1.74 in bovines, and 1.28 in swine. This represents a decline in AMR of over 70% compared to the levels in 2000 in bovines and swine, and an increase of 13% for poultry. Trends in resistance inferred from genomic data showed good agreement with U.S. phenotypic surveillance data (weighted mean absolute difference ± standard deviation, 5.86% ± 8.11%). In 2018, resistance to 3rd-generation cephalosporins in bovines, swine, and poultry decreased to 9.97% on average, whereas in quinolones and 4th-generation cephalosporins, resistance increased to 12.53% and 3.87%, respectively. This was concomitant with a decrease of bla_CMY-2 but an increase in bla_CTX-M-65 and gyrA D87Y (encoding a change of D to Y at position 87). Core genome single-nucleotide polymorphism (SNP) phylogenies show that resistance to these antimicrobial classes was predominantly associated with Salmonella enterica serovar Infantis and, to a lesser extent, S. enterica serovar Typhimurium and its monophasic variant I 4,[5],12:i:−, whereas quinolone resistance was also associated with S. enterica serovar Dublin. Between 2000 and 2018, trends in serovar prevalence showed a composition shift where S. Typhimurium decreased while S. Infantis increased. Our findings illustrate the growing potential of using genomes in public databases to track AMR in regions where sequencing capacities are currently expanding.

IMPORTANCE Next-generation sequencing has led to an exponential increase in the number of genomes deposited in public repositories. This growing volume of information presents opportunities to track the prevalence of genes conferring antimicrobial resistance (AMR), a growing threat to the health of humans and animals. Using 22,102 public genomes, we estimated that the prevalence of multidrug resistance (MDR) in the United States decreased in nontyphoidal Salmonella isolates recovered from bovines and swine between 2000 and 2018, whereas it increased in poultry. These trends are consistent with those detected by national surveillance systems that monitor resistance using phenotypic testing. However, using genomes, we identified that genes conferring resistance to critically important antimicrobials were associated with specific MDR serovars that could be the focus for future interventions. Our analysis illustrates the growing potential of public repositories to monitor AMR trends and shows that similar efforts could soon be carried out in other regions where genomic surveillance is increasing.

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

Salmonella enterica serovar Enteritidis (SE) has consistently been the most common serotype associated with the foodborne Salmonellosis worldwide. In this study, the effect of a dietary direct-fed microbial (DFM) and yeast cell walls (YCW) under a challenge of nalidixic acid resistant SE strain using layer chicks has been investigated. A total of 160 newly hatched Dekalb White female chicks were randomly assigned into 2 experimental groups (80 birds/treatment), control group (CON) and treatment group (DY). Chicks were fed ad libitum a non–medicated-corn-soy based diet and DY was supplemented with the combination of DFM and YCW. At 8 days of age, 2.1 × 10⁹ CFU/bird of the SE was given to all chicks by oral administration. On 3 days postinoculation (dpi), 20 chicks/group were euthanized and all cecal contents were collected for analysis. On 6, 10, and 14 dpi, the cecal contents were sampled from 16 chicks per group. The number of SE in the cecal contents was counted using culture-based methods. A 16S rRNA-based microbiota analysis was performed for additional microbial profiling. The CON and DY showed difference (P ≤ 0.05) in β diversity throughout the trial. Prevalence of SE in cecal contents was lower (P ≤ 0.05) in DY across all time-points. Lower abundance of Salmonella spp. was also shown in DY by liner discriminant analysis effect size (LEfSe). DY increased (P ≤ 0.05) diversity of bacterial species in the cecal contents in DY at 10 and 14 dpi. For the SE challenged birds, SE reduction in DY was observed at 3 dpi and until the end of the trial at 14 dpi confirming a numerically larger difference between groups as well as an increase in bacterial species diversity in DY. It could be hypothesized that the SE reduction shown immediately after the challenge and the greater SE reduction shown after 10 dpi may be the synergistic effect of the combined feed additives.

Bacteriocinogenic probiotics as an integrated alternative to antibiotics in chicken production - why and how?

The misuse of antibiotics in the livestock industry has played an important role in the spread of resistant superbugs with severe health implications for humans. With the recent ban on the use of antibiotics in poultry and poultry feed in Canada and the USA, poultry farmers will have to rely on the use of alternatives to antibiotics (such as feed acidifiers, antibodies, bacteriophages, antimicrobial peptides, prebiotics, and probiotics) to maintain the same productivity and health of their livestock. Of particular interest are bacteriocinogenic probiotics, that is, bacterial strains capable of producing bacteriocins that confer health benefits on the host. These bacterial strains have multiple promising features, such as the ability to attach to the host mucosa, colonize, proliferate, and produce advantageous products such as bacteriocins and short-chain fatty acids. These not only affect pathogenic colonization but improve poultry phenotype as well. Bacteriocins are antimicrobial peptides with multiple promising features such as being non-harmful for human and animal consumption, non-disruptive to the host microbiota eubiosis, non-cytotoxic, and non-carcinogenic. Therefore, bacteriocinogenic probiotics are at the forefront to be excellent candidates for effective replacements to antibiotics. While evidence of their safety and effectiveness is accumulating in vitro and in vivo in inhibiting pathogens while promoting animal health, their safety and history of use in livestock remains unclear and requires additional investigations. In the present paper, we review the safety assessment regulations and commercialization policies on existing and novel bacteriocinogenic and bacteriocin products intended to be used in poultry feed as an alternative to antibiotics.

Phage cocktail SalmoFREE® reduces Salmonella on a commercial broiler farm

According to the World Health Organization, Salmonella is one of the most important zoonotic foodborne pathogens. Poultry products are thought to be the main source of Salmonella, which means that it is necessary to control Salmonella at the pre-harvest stage. Bacteriophages, acting as host-specific parasites of bacterial cells, represent one of the alternatives to antibiotics that can contribute to food safety and security. The present study evaluated the effectiveness of the bacteriophage cocktail SalmoFREE^® to control Salmonella on a commercial broiler farm. We assessed the relationship between the use of SalmoFREE^® and productivity parameters (feed conversion, weight gain, homogeneity). Two field trials (trial 1 n = 34,986; trial 2 n = 34,680) were carried out under commercial rearing conditions on a Colombian broiler farm with a record of Salmonella presence. Each trial comprised 2 control chicken houses and 2 experimental ones. SalmoFREE^® and a control suspension were delivered in the drinking water at 3 time points in the production cycle, and the presence of Salmonella was assessed in cloacal swabs the day before and after the treatments. Results revealed that SalmoFREE^® controls the incidence of Salmonella and does not affect the animals nor the production parameters, demonstrating its efficacy and innocuity at the production scale. We detected phage-specific genes in samples of total DNA extracted from ceca after the treatment with SalmoFREE^®, and tested for the appearance of cocktail-resistant Salmonella, which showed to be an uncommon event. These results contribute relevant information to the adoption of phage therapy as an alternative to growth-promoter antibiotics on poultry farms.

Antagonistic trait of Lactobacillus reuteri S5 against Salmonella enteritidis and assessment of its potential probiotic characteristics

Salmonella enteritidis is an important foodborne pathogen that has caused multiple outbreaks of infection associated with poultry and egg consumption. Thus, the prevention and inhibition of Salmonella enteritidis infection are of great concern. Lactic acid bacteria have anti-pathogenic activity; however, their underlying mechanisms and modes of action have not yet been clarified. In this study, the antibacterial mechanism of Lactobacillus reuteri S5 (L. reuteri S5) against Salmonella enteritidis ATCC13076 (S. enteritidis ATCC13076) was studied by different methods. We found that L. reuteri S5 was able to form a stable biofilm formation, colonizing the entire intestinal tract of chickens. In addition, bacterial cultures and the cell-free supernatant (CFS) of L. reuteri S5 inhibited SE ATCC13076 growth, and this growth inhibition was also observed in the co-culture assay. This effect may be predominantly caused by antimicrobial metabolites produced by L. reuteri S5. Furthermore, treatment with the CFS of L. reuteri S5 resulted in a significant reduction in the expression of Salmonella virulence, motility and adhesion genes and a significant reduction in the motility ability and inhibitory effect on biofilm formation. In addition, the damage to the membrane structure and intracellular structure induced by the CFS of L. reuteri S5 could be observed on Transmission electron microscopy images and dodecyl sulfate, sodium salt (SDS)-Polyacrylamide gel electrophoresis confirmed the disruptive action of the CFS of L. reuteri S5 on the cytoplasmic membrane. Our findings demonstrate that L. reuteri S5, an intestinal Lactobacillus species associated with chicken health, is able to form biofilm and stably colonize chicken intestines. It also possesses anti-SE activity, preventing SE growth, inhibits the expression of SE genes involved in adhesion and invasion, virulence and cell membrane integrity, inhibits SE biofilm formation and motility, damages or destroys bacterial structures, and inhibits intracellular protein synthesis. L. reuteri S5 therefore has potential applications as a probiotic agent.

Identification and selection of food safety-related risk factors to be included in the Canadian Food Inspection Agency's Establishment-based Risk Assessment model for Hatcheries

Towards the continuous improvement of its inspection system, the Canadian Food Inspection Agency (CFIA) is developing an Establishment-based Risk Assessment model for Hatcheries to allocate inspection resources based on the food safety risk associated with the Canadian hatcheries falling under its jurisdiction. The objectives of the current study were to identify and select critical food safety-related risk factors that would be included in this model, with a main focus on Salmonella. A literature review was used to develop a comprehensive list of risk factors that could potentially contribute to the food safety risk attributed to Canadian hatcheries operating in all production streams (breeders, layers, broilers, turkeys, waterfowl and game birds). The development of this list used a selection process that was conducted according to the availability of data sources, the clarity of definition and the measurability of the selected risk factors. A panel of experts reviewed and adjusted the identified risk factors. A final list of 29 risk factors was generated; 20 originated from the scientific literature and nine from the expert panel. Risk factors were grouped in three clusters according to whether they pertained to the inherent risk (nine factors identified), risk mitigation (nine factors identified) or compliance of a hatchery with its preventive control plan and regulatory requirements (11 factors identified). Criteria for assessing each risk factor were defined based on common practices used in the Canadian hatchery industry. This comprehensive list of risk factors and criteria represents useful information to support the design and implementation of a Canadian risk assessment model for hatcheries, but could also be used by like-minded food safety authorities.

Longitudinal study reveals persistent environmental Salmonella Heidelberg in Brazilian broiler farms

The vast capacity for maintenance and dissemination in the environment are major challenges for the control of Salmonella spp. in poultry farms. The aim of this study was to assess environmental contamination by non-typhoidal Salmonella in successive broiler flocks in nine commercial broiler farms integrated with three companies in the south of Brazil, for a twelve-month production period. Recycled broiler litter, feed and swabs from the evaporative cooling system pads were analyzed, and the total enterobacteria count in the litter samples was ascertained. Positive broiler houses were identified in two of the three broiler companies studied, in which non-typhoidal Salmonella were detected for the first time in the first or second flock, and recurred in the recycled litter of subsequent flocks. Feed and evaporative cooling pad swab samples were also positive in at least one of the assessed flocks. The majority of the isolates (87.5%) originating from different flocks, broiler houses and companies that were sampled were identified as S. Heidelberg, with the prevalence of one single genotype. The total enterobacteria levels in the litter diminished as the flocks progressed, but the presence of Salmonella spp. was constant over the course of time, indicating that the litter management procedures were not capable of interrupting the cycle of residual contamination. The predominance of S. Heidelberg highlights its emergence and dissemination in this region, as well as its resistance and maintenance in the environment, and reinforces the need to improve prevention and recycled litter management measures.

Lactobacillus bulgaricus, Lactobacillus rhamnosus and Lactobacillus paracasei Attenuate Salmonella Enteritidis, Salmonella Heidelberg and Salmonella Typhimurium Colonization and Virulence Gene Expression In Vitro

Salmonella Enteritidis (SE), Salmonella Typhimurium (ST), and Salmonella Heidelberg (SH) have been responsible for numerous outbreaks associated with the consumption of poultry meat and eggs. Salmonella colonization in chicken is characterized by initial attachment to the cecal epithelial cells (CEC) followed by dissemination to the liver, spleen, and oviduct. Since cecal colonization is critical to Salmonella transmission along the food chain continuum, reducing this intestinal association could potentially decrease poultry meat and egg contamination. Hence, this study investigated the efficacy of Lactobacillus delbreuckii sub species bulgaricus (NRRL B548; LD), Lactobacillus paracasei (DUP-13076; LP), and Lactobacillus rhamnosus (NRRL B442; LR) in reducing SE, ST, and SH colonization in CEC and survival in chicken macrophages. Additionally, their effect on expression of Salmonella virulence genes essential for cecal colonization and survival in macrophages was evaluated. All three probiotics significantly reduced Salmonella adhesion and invasion in CEC and survival in chicken macrophages (p < 0.05). Further, the probiotic treatment led to a significant reduction in Salmonella virulence gene expression (p < 0.05). Results of the study indicate that LD, LP, and LR could potentially be used to control SE, ST, and SH colonization in chicken. However, these observations warrant further in vivo validation.