The chicken, the egg and Salmonella enteritidis

Predictors of Salmonella enterica contamination in agricultural and livestock-impacted natural watersheds

Salmonella enterica (S. enterica), a ubiquitous zoonotic foodborne pathogen, remains a worldwide public health hazard and economic burden. In recent years, outbreaks associated with the consumption of plant-based foods probably contaminated by irrigation water highlights the importance of water sources. This study investigated anthropogenic and environmental factors influencing S. enterica occurrence in natural watersheds impacted by agricultural and livestock industries in a 10-month longitudinal study in Paraiba, Brazil. Water samples were obtained from multiple sites within the three major river basins by modified Moore Swabs (MMS) and processed by conventional S. enterica isolation methodologies. Physicochemical parameters, climate, and human activities near the water sources were recorded. A logistic regression model was fitted using Generalized Linear Model (GLM) and further adjusted according to the selected variables using the Least Absolute Shrinkage and Selection Operator (LASSO) method. A non-statistical decision tree model was also fitted using the rpart package in R. Season, rainfall regime, water physicochemical features, and anthropogenic activities were significantly associated with S. enterica contamination. According to the regression tree analysis, rainfall within the sampling month was the strongest predictor of S. enterica recovery, potentially due to leaching from soil or runoff from adjacent human and animal activities. The complexity of multivariate conditions driving S. enterica contamination in surface waters highlights the need for region-specific investigations.

Potential of saccharomyces cerevisiae fermentation-derived postbiotic technology in mitigating multiple drug-resistant Salmonella enterica serovars in an in vitro broiler cecal model

Diamond V Original XPC® is a Saccharomyces cerevisiae fermentation-derived postbiotic technology (SCFP) designed to interact synergistically with the animal to provide health benefits by enhancing immune function, supporting digestive integrity and absorption, and maintaining gastrointestinal (GIT) microbial balance in the host. The current study investigated the effects of 1.25% SCFP on multidrug-resistant (MDR) Salmonella serovars: S. Typhimurium (ATCC 14028), S. Enteritidis, S. Infantis, S. Heidelberg, S. Typhimurium DT104, and S. Reading, and shifts in cecal microbiota populations. Using an anaerobic in vitro poultry cecal model, cecal contents were inoculated with ~ 108 colony forming units (CFU) of MDR Salmonella serovars and incubated for 24 h at 37°C anaerobically. The treatments included: control group consisting of 0.2 g of crushed poultry feed, and a treatment group 0.25 g of feed +  1.25% inclusion of Original XPC® (SCFP). The SCFP significantly reduced five of the six serovars: S. Typhimurium ATCC, S. Enteritidis, S. Infantis, S. Heidelberg, and S. Reading (P <  0.05). Time significantly impacted S. Typhimurium DT104 reduction (P <  0.001). The most significant decrease was observed for S. Enteritidis (3.9 log10 CFU/mL), followed by S. Heidelberg (3.8 log10 CFU/mL), S. Infantis (3.4 log10 CFU/mL), S. Typhimurium ATCC (3 log10 CFU/mL), and S. Reading (1.8 log10 CFU/mL) compared to controls that averaged approximately 1 log10 CFU/mL reduction. Microbiota analysis at 24 h involved genomic DNA extraction, amplification using custom dual-indexed primers, and sequencing on the Illumina MiSeq platform. Sequencing data were analyzed using QIIME2-2021.11. S. Infantis and S. Heidelberg inoculated samples were the only groups that significantly enhanced microbial richness and evenness with SCFP addition at 24 h (P <  0.05). Pairwise comparisons revealed that samples inoculated with S. Reading and S. Typhimurium DT104 exhibited a minor change in microbial composition with SCFP, compared to other serovars that demonstrated increased microbial diversity with SCFP. Additionally, S. Infantis and S. Heidelberg inoculated samples exhibited phylogenetic diversity and microbial abundance with SCFP compared to controls at 24 h (P <  0.05). Lachnospiraceae CHKCI001 was significantly more abundant in SCFP-treated samples compared to controls (ANCOM, P <  0.05), suggesting SCFP impact on cecal fermenters and production of fermentation end products that may impact the ecosystem and inhibit pathogen growth. Although various serovars may exhibit somewhat different responses, SCFP effectively mitigated multiple MDR serovars of Salmonella under in vitro incubation conditions.

Analysis of Salmonella enterica serovar Enteritidis isolates from South Korea based on whole genome sequences, antibiotic resistance, and virulence assays

We compared 15 Salmonella Enteritidis isolates collected in South Korea in 2023: 11 from chickens and 4 from humans. All isolates belonged to ST11, and they were divided into two clusters, rST3888 and rST1425. All four human isolates were colistin-resistant, and mcr-1 was identified in three isolates.

Co-housing with Tibetan chickens improved the resistance of Arbor Acres chickens to Salmonella enterica serovar Enteritidis infection by altering their gut microbiota composition

BACKGROUND

Salmonella enterica serovar Enteritidis (S. Enteritidis) is a global foodborne pathogen that poses a significant threat to human health, with poultry being the primary reservoir host. Therefore, addressing S. Enteritidis infections in poultry is crucial to protect human health and the poultry industry. In this study, we investigated the effect of co-housing Arbor Acres (AA) chickens, a commercial breed susceptible to S. Enteritidis, with Tibetan chickens, a local breed resistant to S. Enteritidis infection, on the resistance of the latter to the pathogen.

RESULTS

Ninety-six 1-day-old Tibetan chickens and 96 1-day-old AA chickens were divided into a Tibetan chicken housed alone group (n = 48), an AA chicken housed alone group (n = 48), and a co-housed group (48 birds from each breed for 2 cages). All birds were provided the same diet, and the experimental period lasted 14 d. At d 7, all chickens were infected with S. Enteritidis, and samples were collected at 1-, 3-, and 7-day-post-infection. We found that the body weight of AA chickens significantly increased when co-housed with Tibetan chickens at 1- and 3-day-post-infection (P < 0.05). In addition, the cecal S. Enteritidis load in AA chickens was significantly reduced at 1-, 3-, and 7-day-post-infection (P < 0.05). Furthermore, the inflammatory response in AA chickens decreased, as evidenced by the decreased expression of pro-inflammatory cytokines NOS2, TNF-α, IL-8, IL-1β, and IFN-γ in their cecal tonsils (P < 0.05). Co-housing with Tibetan chickens significantly increased the height of villi and number of goblet cells (P < 0.05), as well as the expression of claudin-1 (P < 0.05), a tight junction protein, in the jejunum of AA chickens. Further analysis revealed that co-housing altered the gut microbiota composition in AA chickens; specifically, the relative abundances of harmful microbes, such as Intestinimonas, Oscillibacter, Tuzzerella, Anaerotruncus, Paludicola, and Anaerofilum were reduced (P < 0.05).

CONCLUSIONS

Our findings indicate that co-housing with Tibetan chickens enhanced the resistance of AA chickens to S. Enteritidis infection without compromising the resistance of Tibetan chickens. This study provides a novel approach for Salmonella control in practical poultry production.

Modification Effects of Microorganisms and Enzymes on Egg Components: A Review

In eggs, there are several components: eggshell (ES), eggshell membrane (ESM), egg white (EW), and egg yolk (EY). Many modification methods exist, such as thermal treatment, high pressure, freeze-thaw cycles, ultrasonic treatment, ozonation, phosphorylation, and acylation, all aimed at improving the functional properties of EW and EY. Additionally, microorganism and enzyme modifications have proven effective in enhancing the functional properties of EW and EY. ES and ESM are unique components of eggs. The eggshell is rich in calcium carbonate, while the eggshell membrane is rich in protein. The effective utilization of ES and ESM can help promote economic income in the poultry industry and benefit the environment. Research on the modification of ES and ESM has shown that microorganisms and enzymes have the potential to improve their functional properties. After modification, egg components can be utilized in the production of egg-based and other food products for improved performance. Furthermore, enzyme modification of egg components can produce bioactive peptides, which have the potential to treat specific diseases and may even be used in the biomedical field. This review primarily focuses on the effects of microorganisms and enzymes on the modification of egg components and summarizes the roles of microbial and enzymatic modifications in this context.

The effect of peanut skins as a natural antimicrobial feed additive on ileal and cecal microbiota in broiler chickens inoculated with Salmonella enterica Enteritidis

The consumption of poultry products contaminated with Salmonella species is one of the most common causes of Salmonella infections. In vivo studies demonstrated the potential application of peanut skins (PS) as an antimicrobial poultry feed additive to help mitigate the proliferation of Salmonella in poultry environments. Tons of PS, a waste by-product of the peanut industry, are generated and disposed in U.S. landfills annually. Peanut skins and extracts have been shown to possess antimicrobial and antioxidant properties. Hence, we aimed to determine the effect of PS as a feed additive on the gut microbiota of broilers fed a control or PS supplemented (4% inclusion) diet and inoculated with or without Salmonella enterica Enteritidis (SE). At hatch 160 male broilers were randomly assigned to 4 treatments: 1) CON-control diet without SE, 2) PS-PS diet without SE, 3) CONSE-control diet with SE, 4) PSSE-PS diet with SE. On d 3, birds from CONSE and PSSE treatments were inoculated with 4.2 × 109 CFU/mL SE. At termination (4 wk), 10 birds/treatment were euthanized and ileal and cecal contents were collected for 16S rRNA analysis using standard methodologies. Sequencing data were analyzed using QIIME2. No effect of PS or SE was observed on ileal alpha and beta diversity, while evenness, richness, number of amplicon sequence variants (ASV) and Shannon, as well as beta diversity were significantly (P < 0.05) affected in ceca. Similarly, more differentially abundant taxa between treatment groups were identified in ceca than in ileum. However, more microbiota functional changes, based on the PICRUST2 prediction, were observed in ileum. Overall, relatively minor changes in microbiota were observed during SE infection and PS treatment, suggesting that PS addition may not attenuate the SE proliferation, as shown previously, through modulation of microbiota in gastrointestinal tract. However, while further studies are warranted, these results suggest that PS may potentially serve as a functional feed additive for poultry for improvement of animal health.

Utilizing Flaxseed as an Antimicrobial Alternative in Chickens: Integrative Review for Salmonella enterica and Eimeria

This review provides an integrative framework for understanding flaxseed (Linum utassitissimum) as an antimicrobial alternative for poultry production. We begin by familiarizing the reader with the global legislation of antibiotics in animal husbandry; highlighting gaps and current issues for Salmonella enterica (S. enterica) and Eimeria (coccidiosis-inducing). We then discuss the natural, symbiotic characteristics of the Galliformes order (chicken-like birds) and Linum (the flaxes). The key immunological themes in this review include: (i) flaxseed's regulation of innate and adaptive immunity in chickens, (ii) flaxseed's ability to accelerate chicken recovery from infection with S. enterica and Eimeria, and (iii) flaxseed's strengthening of immunity via vitamin B6 antagonism. Research indicates that whole flaxseed increases adaptive immune capacity by augmenting cecal Bacteroides and short-chain fatty acids while also attenuating the heterophil to lymphocyte ratio in chickens. Moreover, flaxseed accelerates chicken recovery from infection with Salmonella Enteritidis or Eimeria tenella; however, future work is needed to better understand (i) defatted flaxseed's superior performance against Eimeria species and (ii) Eimeria maxima's resilience against whole flaxseed. In the context of vitamin B6 antagonism, we propose that 15% whole flaxseed overcomes S. enterica's insult to estrogen synthesis by sustaining the activity of phosphatidylethanolamine methyltransferase (PEMT) in liver. We also propose that 10% defatted flaxseed (as a metformin homologue) strengthens chicken immunity by safeguarding gonadal physiology and by increasing plasma thymidine bioavailability. The concepts in this review can be used as a template for conducting advanced immunological studies in poultry science.

Salmonella serovars trend in poultry Malaysia from 2011 to 2020

Data and geographical trend of Salmonella serovars infecting poultry in Malaysia is limited. In this study, the trend of Salmonella serovars infection was presented for the past ten years from 2011 to 2020 and the predominant serovars were mapped based on geographical distribution. Analysis of passive surveillance data demonstrated a shift of Salmonella serovars that infected poultry in Malaysia. The Salmonella serovars varied within ten years of registered cases with the Veterinary Research Institute, Ipoh, Malaysia involving samples from live and dead birds. Total number of cases found from the year 2011 to 2020 were 391 cases, involving 73 Salmonella serovars with an additional one group of unclassified serovars known as Salmonella spp. Further analysis revealed that eight serovars were found predominant throughout the ten-year period. These included S. Albany, S. Braenderup, S. Brancaster, S. Corvallis, S. Enteritidis, S. Kentucky, S. Typhimurium and S. Weltevreden. Salmonella spp. (Salmonella that is incapable to be identified based on serotyping) were also one of the major groups observed throughout the years. This study could help the authorities to improvise policies for better disease control programs through the establishment of diagnostic tools for rapid Salmonella screening in poultry.

Dissemination of Ceftriaxone-Resistant Salmonella Enteritidis Harboring Plasmids Encoding blaCTX-M-55 or blaCTX-M-14 Gene in China

Salmonella Enteritidis was the primary foodborne pathogen responsible for acute gastroenteritis. The growing ceftriaxone resistance poses a significant threat to public health. Infection with S. Enteritidis has emerged as a major public health concern, particularly in developing countries. However, research on ceftriaxone-resistant S. Enteritidis (CRO-RSE) remains limited, particularly concerning its resistance mechanism, plasmid structure, and transmission characteristics. This study aims to address these gaps comprehensively. We collected 235 S. Enteritidis isolates from Hangzhou First People's Hospital between 2010 and 2020. Among these, 8.51% (20/235) exhibited resistance to ceftriaxone. Whole-genome analysis revealed that 20 CRO-RSE isolates harbored blaCTX-M-55 or blaCTX-M-14 on the plasmid. Moreover, the dissemination of the blaCTX-M-type gene was associated with IS26 and ISEcp1. Plasmid fusion entailing the integration of the p1 plasmid with antibiotic resistance genes and the p2 (pSEV) virulence plasmid was observed in certain CRO-RSE. Additionally, the structural analysis of the plasmids unveiled two types carrying the blaCTX-M-type gene: type A with multiple replicons and type B with IncI1 (Alpha) replicon. Type B plasmids exhibited superior adaptability and stability compared to type A plasmids within Enterobacteriaceae. Interestingly, although the type B (S808-p1) plasmid displayed the potential to spread to Acinetobacter baumannii, it failed to maintain stability in this species.

Protective effects of puerarin on liver tissue in Salmonella-infected chicks: a proteomic analysis

Salmonella enterica is a zoonotic bacterium that not only causes serious economic losses to the livestock and poultry industries but also seriously endangers human health. Long-term indiscriminate use of antibiotics has led to drug resistance in Salmonella, and thus the identification of alternatives to antibiotics is crucial. In this study, the effects of puerarin on the S. enterica-infected chickens were investigated. A total of 360 chicks were randomly assigned as the control group (CON), the S. enterica group (S), and puerarin-treatment group (P). Chicks in the P group were fed the basal diet supplemented with 50 (P50), 100 (P100), 200 (P200), and 400 (P400) mg/kg puerarin, respectively. It was found that puerarin treatment markedly altered the serum activities of aspartate aminotransferase (AST), alanine transaminase (ALT), and superoxide dismutase (SOD), together with the malondialdehyde (MDA) and total antioxidant capacity (T-AOC) contents in the serum. The mRNA expression of IL-6, IL-1β, TNF-α, Bcl-2, and caspase-8 in the livers of S. enterica-infected chicks was increased after infection but significantly reduced after treatment with puerarin. Histologic analysis showed that puerarin effectively mitigated morphological damage in the liver caused by S. enterica. Proteomic analysis revealed that S. enterica infection led to metabolic disorders in the liver, resulting in oxidative stress, increased inflammation, and significantly elevated levels of hepatocellular carcinoma biomarkers. The findings of the filtered sequencing were verified by using quantitative PCR (qPCR). Treatment with 100 mg/mL puerarin thus effectively alleviated disordered liver metabolism, reduced inflammation and oxidative damage and significantly reduced the levels of hepatocellular carcinoma biomarkers in the liver. The results suggest that puerarin has the potential to replace antibiotics to control Salmonella infection in poultry and thus improve food safety.

Anti-Salmonella Defence and Intestinal Homeostatic Maintenance In Vitro of a Consortium Containing Limosilactobacillus fermentum 3872 and Ligilactobacillus salivarius 7247 Strains in Human, Porcine, and Chicken Enterocytes

Limosilactobacillus fermentum strain 3872 (LF3872) was originally isolated from the breast milk of a healthy woman during lactation and the breastfeeding of a child. Ligilactobacillus salivarius strain 7247 (LS7247) was isolated at the same time from the intestines and reproductive system of a healthy woman. The genomes of these strains contain genes responsible for the production of peptidoglycan-degrading enzymes and factors that increase the permeability of the outer membrane of Gram-negative pathogens. In this work, the anti-Salmonella and intestinal homeostatic features of the LF3872 and LS7247 consortium were studied. A multi-drug resistant (MDR) strain of Salmonella enteritidis (SE) was used in the experiments. The consortium effectively inhibited the adhesion of SE to intact and activated human, porcine, and chicken enterocytes and reduced invasion. The consortium had a bactericidal effect on SE in 6 h of co-culturing. A gene expression analysis of SE showed that the cell-free supernatant (CFS) of the consortium inhibited the expression of virulence genes critical for the colonization of human and animal enterocytes. The CFS stimulated the production of an intestinal homeostatic factor-intestinal alkaline phosphatase (IAP)-in Caco-2 and HT-29 enterocytes. The consortium decreased the production of pro-inflammatory cytokines IL-8, TNF-α, and IL-1β, and TLR4 mRNA expression in human and animal enterocytes. It stimulated the expression of TLR9 in human and porcine enterocytes and stimulated the expression of TLR21 in chicken enterocytes. The consortium also protected the intestinal barrier functions through the increase of transepithelial electrical resistance (TEER) and the inhibition of paracellular permeability in the monolayers of human and animal enterocytes. The results obtained suggest that a LF3872 and LS7247 consortium can be used as an innovative feed additive to reduce the spread of MDR SE among the population and farm animals.

Metabolomic and microbiome analysis of the protective effects of Puerarin against Salmonella Enteritidis Infection in chicks

BACKGROUND

Salmonella Enteritidis is a zoonotic pathogen and poses a substantial risk to human health, as well as significant financial losses to the livestock and poultry industries. It is currently urgent to identify alternatives to antibiotic treatment.

RESULTS

In this study, we explored the influence of Puerarin on the immunological response, intestinal flora, serum metabolome, and growth performance of chicks infected with Salmonella Enteritidis. Chicks were weighed at specific time points and the average daily gain (ADG) was calculated. Serum, intestinal, and cecal content samples were collected on days 10 and 17. The results showed that 100 mg/kg of Puerarin significantly suppressed inflammation and enhanced immune function. Metabolomic analysis showed significant differences in serum metabolites after Puerarin treatment and suggested that Puerarin may regulate abnormal amino acid and lipid metabolism after Salmonella Enteritidis infection through the autophagic and ABC transporter pathways. In addition, Puerarin suppressed Salmonella Enteritidis-induced intestinal flora dysbiosis through modulation of the microbial community structures (increased Lactobacillus, Faecalibacterium, and Subdoligranulum), as demonstrated by 16S rRNA analysis.

CONCLUSIONS

In conclusion, Puerarin can improve growth performance in chicks, suppress the inflammatory response in vivo, enhance immunity, and regulate lipid and amino acid metabolism and the intestinal flora.

Pathogenic Escherichia coli, Salmonella spp. and Campylobacter spp. in Two Natural Conservation Centers of Wildlife in Portugal: Genotypic and Phenotypic Characterization

Human-wildlife coexistence may increase the potential risk of direct transmission of emergent or re-emergent zoonotic pathogens to humans. Intending to assess the occurrence of three important foodborne pathogens in wild animals of two wildlife conservation centers in Portugal, we investigated 132 fecal samples for the presence of Escherichia coli (Shiga toxin-producing E. coli (STEC) and non-STEC), Salmonella spp. and Campylobacter spp. A genotypic search for genes having virulence and antimicrobial resistance (AMR) was performed by means of PCR and Whole-Genome Sequencing (WGS) and phenotypic (serotyping and AMR profiles) characterization. Overall, 62 samples tested positive for at least one of these species: 27.3% for STEC, 11.4% for non-STEC, 3.0% for Salmonella spp. and 6.8% for Campylobacter spp. AMR was detected in four E. coli isolates and the only Campylobacter coli isolated in this study. WGS analysis revealed that 57.7% (30/52) of pathogenic E. coli integrated genetic clusters of highly closely related isolates (often involving different animal species), supporting the circulation and transmission of different pathogenic E. coli strains in the studied areas. These results support the idea that the health of humans, animals and ecosystems are interconnected, reinforcing the importance of a One Health approach to better monitor and control public health threats.

Use of Phages to Treat Antimicrobial-Resistant Salmonella Infections in Poultry

Salmonellosis is one of the most common bacterial infections that impacts both human health and poultry production. Although antibiotics are usually recommended for treating Salmonella infections, their misuse results in the evolution and spread of multidrug-resistant (MDR) bacteria. To minimize the health and economic burdens associated with antimicrobial resistance, a novel antibacterial strategy that can obliterate pathogens without any adverse effects on humans and animals is urgently required. Therefore, therapeutic supplementation of phages has gained renewed attention because of their unique ability to lyse specific hosts, cost-effective production, environmentally-friendly properties, and other potential advantages over antibiotics. In addition, the safety and efficacy of phage therapy for controlling poultry-associated Salmonella have already been proven through experimental studies. Phages can be applied at every stage of poultry production, processing, and distribution through different modes of application. Despite having a few limitations, the optimized and regulated use of phage cocktails may prove to be an effective option to combat infections caused by MDR pathogens in the post-antibiotic era. This article mainly focuses on the occurrence of salmonellosis in poultry and its reduction with the aid of bacteriophages. We particularly discuss the prevalence of Salmonella infections in poultry and poultry products; review the trends in antibiotic resistance; and summarize the application, challenges, and prospects of phage therapy in the poultry industry.

Emergence, Dissemination and Antimicrobial Resistance of the Main Poultry-Associated Salmonella Serovars in Brazil

Salmonella infects poultry, and it is also a human foodborne pathogen. This bacterial genus is classified into several serovars/lineages, some of them showing high antimicrobial resistance (AMR). The ease of Salmonella transmission in farms, slaughterhouses, and eggs industries has made controlling it a real challenge in the poultry-production chains. This review describes the emergence, dissemination, and AMR of the main Salmonella serovars and lineages detected in Brazilian poultry. It is reported that few serovars emerged and have been more widely disseminated in breeders, broilers, and layers in the last 70 years. Salmonella Gallinarum was the first to spread on the farms, remaining as a concerning poultry pathogen. Salmonella Typhimurium and Enteritidis were also largely detected in poultry and foods (eggs, chicken, turkey), being associated with several human foodborne outbreaks. Salmonella Heidelberg and Minnesota have been more widely spread in recent years, resulting in frequent chicken/turkey meat contamination. A few more serovars (Infantis, Newport, Hadar, Senftenberg, Schwarzengrund, and Mbandaka, among others) were also detected, but less frequently and usually in specific poultry-production regions. AMR has been identified in most isolates, highlighting multi-drug resistance in specific poultry lineages from the serovars Typhimurium, Heidelberg, and Minnesota. Epidemiological studies are necessary to trace and control this pathogen in Brazilian commercial poultry production chains.

Inactivated pentavalent vaccine against mycoplasmosis and salmonellosis for chickens

Mycoplasma and Salmonella are serious pathogens threaten the poultry industry. This study aimed to prepare and evaluate an inactivated pentavalent vaccine targeting bacteria, including Salmonella enterica serovar Typhimurium (ST), Salmonella enterica serovar Enteritidis (SE), Salmonella enterica serovar Kentucky (SK), Mycoplasma gallisepticum (MG), and Mycoplasma synoviae (MS), from locally isolated strains. The prepared vaccine was adjuvanted with Montanide ISA70 oil and then tested for safety, sterility, and potency. The vaccine efficacy was evaluated in 110 specific pathogen-free, 1-day-old chicks, which were divided into three groups as follows: 1) vaccinated group (50 birds), which was subdivided into five subgroups of ten birds each; 2) control positive (challenged) group (50 birds), which was subdivided into five subgroups of ten birds each; and 3) control negative (blank) group, which included ten birds. Chicks in group 1 were administered the first dose of vaccine at 7 d of age followed by a booster dose after 3 wk. At 3 wk after booster vaccination, the chicks who were administered the booster dose were challenged and kept under observation until the end of the experiment when the chicks were approximately 10 wk. Details of clinical symptoms, daily mortality, weights, and postmortem lesions; serum samples; cloacal swabs; and nasal swabs were collected during the experiment. The humoral immune response to the prepared pentavalent vaccine was assessed using enzyme-linked immunosorbent assay. Our findings revealed that the prepared vaccine showed high protective antibody titers against Salmonella and Mycoplasma with 100% efficacy and no mortalities (100% survival rate) were recorded in vaccinated and challenged birds. The vaccine reduced both clinical signs and bacterial shedding post challenge in vaccinated birds in comparison with control positive group. The prepared vaccine did not affect the body weight gain of the vaccinated birds in comparison with control negative birds. The current study concluded that locally manufactured inactivated pentavalent vaccine offers protection to birds and could be employed as an effective tool along with biosecurity measures to overcome mycoplasmosis and salmonellosis in layer and breeder chicken farms in Egypt.

Characterisation of Salmonella Enteritidis ST11 and ST1925 Associated with Human Intestinal and Extra-Intestinal Infections in Singapore

Salmonella Enteritidis is a major foodborne pathogen worldwide. In this study, a total of 276 S. enteritidis isolates, collected between 2016 and 2017 from human, food and farm/slaughterhouse samples, were studied to enhance the understanding of the epidemiology of human salmonellosis in Singapore. Results showed all 276 isolates belonged either to ST1925 (70.3%) or ST11 (29.7%), with ST11 being significantly more frequent in extra-intestinal isolates and chicken isolates. Food isolates, most of which were from poultry, showed the highest prevalence of resistance (33–37%) against beta-lactams or beta-lactams/beta-lactamase inhibitor combination (ampicillin, piperacillin and ampicillin/sulbactam). The analysis showed the detection of genes associated with resistance to aminoglycoside genes (99.6%), tetracycline (55.1%), and beta-lactams (14.9%) of all isolates. Nine types of plasmids were found in 266 isolates; the most common incompatibility group profiles were IncFIB(S)-IncFII(S)-IncX1 (72.2%) and IncFIB(S)-IncFII(S) (15.8%). Most plasmid harbouring isolates from chicken (63.6%, 14/22) and from human (73.8%, 175/237) shared the same plasmid profile (IncFIB(S)-IncFII(S)-IncX1). SNP analysis showed clustering of several isolates from poultry food products and human isolates, suggesting phylogenetic relatedness among these isolates. Lastly, this study provides important epidemiological insights on the application of phenotypic and next-generation sequencing (NGS) tools for improved food safety and public health surveillance and outbreak investigation of S.enteritidis.

Differential immunological response detected in mRNA expression profiles among diverse chicken lines in response to Salmonella challenge

Salmonella enterica serovar Enteritidis is a bacterial pathogen that contributes to poultry production losses and human foodborne illness. The bacterium elicits a broad immune response involving both the innate and adaptive components of the immune system. Coordination of the immune response is largely directed by cytokines. The objective of the current study was to characterize the expression of a select set of cytokines and regulatory immune genes in three genetically diverse chicken lines after infection with S. Enteritidis. Leghorn, Fayoumi and broiler day-old chicks were orally infected with pathogenic S. Enteritidis or culture medium. At 2 and 18 h postinfection, spleens and ceca were collected and mRNA expression levels for 7 genes (GM-CSF, IL2, IL15, TGF-β1, SOCS3, P20K, and MHC class IIβ) were evaluated by real-time quantitative PCR. Genetic line had a significant effect on mRNA expression levels of IL15, TGF-β1, SOCS3 and P20K in the spleen and on P20K and MHC class IIβ in the cecum. Comparing challenged vs. unchallenged birds, the expression of SOCS3 and P20K mRNA were significantly higher in the spleen and cecum, while MHC class IIβ mRNA was significantly lower in spleen. Combining the current RNA expression results with those of previously reported studies on the same samples reveals distinct RNA expression profiles among the three genetic chicken lines and the 2 tissues. This study illustrates that these diverse genetic lines have distinctively different immune response to S. Enteritidis challenge within the spleen and the cecum.

Genomic Characterization of a Nalidixic Acid-Resistant Salmonella Enteritidis Strain Causing Persistent Infections in Broiler Chickens

Virulent strains of Salmonella enterica subsp. enterica serovar Enteritidis (SE) harbored by poultry can cause disease in poultry flocks and potentially result in human foodborne illness. Two broiler flocks grown a year apart on the same premises experienced mortality throughout the growing period due to septicemic disease caused by SE. Gross lesions predominantly consisted of polyserositis followed by yolk sacculitis, arthritis, osteomyelitis, and spondylitis. Tissues with lesions were cultured yielding 59 SE isolates. These were genotyped by Rep-PCR followed by whole-genome sequencing (WGS) of 15 isolates which were clonal. The strain, SE_TAU19, was further characterized for antimicrobial susceptibility and virulence in a broiler embryo lethality assay. SE_TAU19 was resistant to nalidixic acid and sulfadimethoxine and was virulent to embryos with 100% mortality of all challenged broiler embryos within 3.5 days. Screening the SE_TAU19 whole-genome sequence revealed seven antimicrobial resistance (AMR) genes, 120 virulence genes, and two IncF plasmid replicons corresponding to a single, serovar-specific pSEV virulence plasmid. The pef, spv, and rck virulence genes localized to the plasmid sequence assembly. We report phenotypic and genomic features of a virulent SE strain from persistently infected broiler flocks and present a workflow for SE characterization from isolate collection to genome assembly and sequence analysis. Further SE surveillance and investigation of SE virulence in broiler chickens is warranted.

Antimicrobial and Antibiofilm Effect of ε-Polylysine against Salmonella Enteritidis, Listeria monocytogenes, and Escherichia coli in Tryptic Soy Broth and Chicken Juice

ε-Polylysine (ε-PL) is a safe food additive that is used in the food industry globally. This study evaluated the antimicrobial and antibiofilm activity of antibacterial peptides (ε-PL) against food poisoning pathogens detected in chicken (Salmonella Enteritidis, Listeria monocytogenes, and Escherichia coli). The results showed that minimum inhibitory concentrations (MICs) ranged between 0.031-1.0 mg/mL, although most bacterial groups (75%) showed MICs of 1.0 mg/mL. The reduction in the cell viability of pathogens due to ε-PL depended on the time and concentration, and 1/2 × MIC of ε-PL killed 99.99% of pathogens after 10 h of incubation. To confirm biofilm inhibition and degradation effects, crystal violet assay and confocal laser scanning microscopy (CLSM) were used. The biofilm formation rates of four bacterial groups (Salmonella, Listeria, E. coli, and multi-species bacteria) were 10.36%, 9.10%, 17.44%, and 21.37% at 1/2 × MIC of ε-PL, respectively. Additionally, when observed under a CLSM, ε-PL was found to induce biofilm destruction and bacterial cytotoxicity. These results demonstrated that ε-PL has the potential to be used as an antibiotic and antibiofilm material for chicken meat processing.

A Comparison of Colonizing Ability Between Salmonella Enteritidis and Salmonella Heidelberg in Broiler Chickens Challenged Through Feed Administration

With over 1 million estimated cases per year in the United States, foodborne salmonellosis is an important public health issue. Chicken products are frequent sources of foodborne Salmonella infection. These bacteria readily colonize the gastrointestinal tract of broiler chickens, and feed is a known vector. Past research has demonstrated that the survivability of Salmonella in feed is dependent on the serovar and strain. Therefore, the objective of this research was to compare colonization incidence of these two serovars in broiler chicken tissues by administration of feed contaminated with Salmonella enterica serovar Enteritidis (SE) or Salmonella enterica serovar Heidelberg (SH). A comparison was made with equal conditions so that there was no influence of other factors. Birds were inoculated by addition of Salmonella to the feed (1 × 10⁴ colony-forming unit [CFU]/g of feed) at 14 days of age, and the following tissue samples were collected from each bird after grow-out (days 34-41 depending on the trial): abdominal cavity swab, bone marrow swab, cloaca swab, lung swab, breast, bursa and thymus, ceca, crop, kidney, liver and spleen, skin, spinal cord, thigh, and trachea. A higher percentage of birds inoculated with SE were positive in at least one tissue compared with SH (68% and 9%, respectively), and the SE inoculated birds also showed a higher number of positive tissue samples than SH (13.1% and 0.7%, respectively). Recovery of SH was low for all tissue samples. However, recovery of SE was variable between samples, with ceca showing the highest percentage (50%). These results indicate that challenge at day 14 through feed administration results in greater colonization by SE compared with SH, suggesting that monitoring and control methods for Salmonella in feed should focus on SE to have the greatest positive effect.

The combined effect of stressful factors (temperature and pH) on the expression of biofilm, stress, and virulence genes in Salmonella enterica ser. Enteritidis and Typhimurium

Salmonella enterica is a major food borne pathogen that creates biofilm. Salmonella biofilm formation under different environmental conditions is a public health problem. The present study was aimed to evaluate the combined effects of stressful factors (temperature and pH) on the expression of biofilm, stress, and virulence genes in Salmonella Enteritidis and Salmonella Typhimurium. In this study, the effect of temperature (2, 8, 22.5, 37, 43 °C) and pH (2.4, 3, 4.5, 6, 6.6) on the expression of biofilm production genes (adr A, bap A), virulence genes (hil A, inv A) and the stress gene (RpoS) of S. Enteritidis and S. Typhimurium was evaluated. The response surface methodology (RSM) approach was used to evaluate the combined effect of the above factors. The highest expression of adr A, bap A, hil A, and RpoS gene for S. Typhimurium was at 22 °C-pH 4.5 (6.39-fold increase), 37 °C-pH 6 (3.92-fold increase), 37 °C-pH 6 (183-fold increase), and 37 °C-pH 3 (43.8-fold increase), respectively. The inv A gene of S. Typhimurium was decreased in all conditions. The adr A, bap A, hil A, inv A, and RpoS gene of S. Enteritidis had the highest expression level at 8 °C-pH 3 (4.09-fold increase), 22 °C-pH 6 (2.71-fold increase), 8 °C pH 3 (190-fold increase), 22 °C-pH 4.5 (9.21-fold increase), and 8 °C-pH 3 (16.6-fold), respectively. Response surface methodology (RSM) indicated that the temperature and pH had no significant effect on the expression level of adr A, bap A, hil A, Inv A, and RpoS gene in S. Enteritidis and S. Typhimurium. The expression of biofilm production genes (adr A, bap A), virulence genes (hil A, inv A) and the stress gene (RpoS) of S. Enteritidis and S. Typhimurium is not directly and exclusively associated with temperature and pH conditions.

Microbial Load and Prevalence of Escherichia coli and Salmonella spp. in Macadamia Nut Production Systems

ABSTRACT

This study evaluated the potential impact of environmental factors and harvesting practices on the microbial load of macadamia nuts. Three farms located in primary macadamia nut production regions, the Mbombela (A), Barberton (B) and White River (C) areas in Mpumalanga Province, South Africa, were sampled over a 2-year period. A total of 264 irrigation water (54), soil (30), and macadamia nut (180) samples were collected and evaluated for microbial load. All water samples had mean Escherichia coli loads below 1,000 MPN/100 mL, which is the standard regulatory requirement for agricultural water considered fit for irrigation in South Africa. Mean total aerobic plate counts of nut-in-husk on-tree samples (3.91 log CFU/g; n = 60) were higher after harvesting (5.98 log CFU/g; n = 60) but were lower after dehusking (to 4.89 log CFU/g; n = 60) on nut-in-shell samples. Salmonella spp. were only detected in water samples from farm B (67%; n = 18) and farm C (15%; n = 18). Neither Listeria monocytogenes nor Salmonella spp. were detected in the soil samples. E. coli was only detected in 20% (n = 10) of soil samples collected from two farms (farms A and B). None of the E. coli isolated in this study was positive for the eae, stx1, and stx2 enterohemorrhagic E. coli virulence genes. This study provides basic data that can be used in the development of macadamia nut-specific hazard assessment tools within primary production environments.

HIGHLIGHTS

Salmonella Serovars, Antibiotic Resistance, and Virulence Factors Isolated from Intestinal Content of Slaughtered Chickens and Ready-to-Eat Chicken Gizzards in the Ilorin Metropolis, Kwara State, Nigeria

Salmonellosis is one of the most common and widely distributed food-borne diseases, and the presence of antimicrobial-resistant Salmonella in poultry and poultry products is a global public health problem. Therefore, a cross-sectional study was conducted from November 2016 to July 2017 with an aim of determining the isolation rates of Salmonella species from the intestinal contents of slaughtered chickens, the most common serotypes that invade and colonize the tissues of chickens in Ilorin, and the susceptibilities of the isolated species to commonly used antibiotics. Four hundred samples of intestinal contents from apparently healthy slaughtered chickens and one hundred ready-to-eat chicken gizzards in Ilorin, Kwara State, were examined for the presence of Salmonella and their serotypes. Salmonellae were isolated and identified according to the techniques recommended by the World Health Organization: preenrichment, selective plating, biochemical testing, and serotyping. A total number of forty-three (43) Salmonella isolates consisting of 33 from intestinal contents and 10 from ready-to-eat chicken gizzards were isolated and identified. There was an overall Salmonella prevalence rate of 8.6% (43/500), and the isolates were distributed as follows: gizzard, 2% (n = 10) and intestinal contents, 6.6% (n = 33). The predominant serovars were Salmonella enterica subsp. enterica serovar 45: d: 1, 7 (16) and S. Haifa (5). All ready-to-eat chicken gizzards were associated with Salmonella enterica subsp. enterica serovar 45: d: 1, 7 (5). The Salmonella from intestinal contents belong to Salmonella enterica subsp. enterica serovars 45: d: 1, 7 (11) and S. Haifa (5). Salmonella species isolated were 100% resistant to ciprofloxacin, ampicillin, and ceftazidime. This is followed by cloxacillin (81%), tetracycline (75%), and sulfamethoxazole (67%). The Salmonella isolates were, however, 100% sensitive to enrofloxacin, 74% to streptomycin, and 72% to gentamycin antibiotics. The most common serotype was S. enterica subsp. enterica serovar 45: d: 1, 7. All the twenty five Salmonella serovars consisting of twenty-one serotypes (n = 21), two of the Salmonella that could not be cultured after enrichment, and the two that were contaminated with Proteus possessed the virulence genes of invA and stn. The Salmonella enterica subsp. enterica serovar 45: d: 1, 7 and S. Haifa possess virulence genes so they are potentially virulent for humans in this area. The national and local health authorities in Nigeria should improve hygiene measures especially at retail slaughter markets to reduce salmonellosis which is one of the most important food-borne diseases in humans.

Effect of Feeding a Postbiotic Derived from Saccharomyces cerevisiae Fermentation as a Preharvest Food Safety Hurdle for Reducing Salmonella Enteritidis in the Ceca of Layer Pullets

ABSTRACT

Salmonella Enteritidis is responsible for a significant proportion of foodborne salmonellosis in the United States and continues to be attributable to table eggs despite increased federal oversight. Technologies, including feed additives, continue to be evaluated for preharvest application and their potential food safety benefits. Diamond V Original XPC, a Saccharomyces cerevisiae fermentation-based postbiotic (SCFP), was evaluated for its effectiveness in reducing Salmonella Enteritidis (SE) colonization in young layer pullets. A total of 40 day-old Hy-Line W-36 layer pullets were equally divided and randomly assigned to one of two dietary treatments, with SCFP or without SCFP (PCON), and orally gavaged on day 28 with SE at 106 CFU/mL. Another 20 day-old pullets were fed the same control feed without SCFP and blank inoculated on day 28 with 1 mL of sterile phosphate-buffered saline to serve as a negative control. Qualitative and quantitative analyses of cecal contents for Salmonella were performed for all birds on day 32. The prevalence of SE in the ceca of all directly challenged birds was 100%; however, the SE concentration in birds fed SCFP diet (3.35 log CFU/g) was significantly lower (P < 0.0001) than that of the PCON birds not fed SCFP (4.49 log CFU/g). The proportion of birds with enumerable SE concentrations was lower in SCFP-fed pullets (57.9%) than in the PCON pullets (95.0%). These data suggest that inclusion of SCFP in the diet may aid in the reduction of SE within the ceca of commercial laying hens and could serve as an additional preharvest food safety hurdle.

HIGHLIGHTS

Survival and Control of Campylobacter in Poultry Production Environment

Campylobacter species are Gram-negative, motile, and non-spore-forming bacteria with a unique helical shape that changes to filamentous or coccoid as an adaptive response to environmental stresses. The relatively small genome (1.6 Mbp) of Campylobacter with unique cellular and molecular physiology is only understood to a limited extent. The overall strict requirement of this fastidious microorganism to be either isolated or cultivated in the laboratory settings make itself to appear as a weak survivor and/or an easy target to be inactivated in the surrounding environment of poultry farms, such as soil, water source, dust, surfaces and air. The survival of this obligate microaerobic bacterium from poultry farms to slaughterhouses and the final poultry products indicates that Campylobacter has several adaptive responses and/or environmental niches throughout the poultry production chain. Many of these adaptive responses remain puzzles. No single control method is yet known to fully address Campylobacter contamination in the poultry industry and new intervention strategies are required. The aim of this review article is to discuss the transmission, survival, and adaptation of Campylobacter species in the poultry production environments. Some approved and novel control methods against Campylobacter species throughout the poultry production chain will also be discussed.

Biofilm-Formation-Related Genes csgD and bcsA Promote the Vertical Transmission of Salmonella Enteritidis in Chicken

The contamination of Salmonella Enteritidis in eggs and chicken meat via vertical transmission has become a worldwide public health concern. Biofilm formation by S. Enteritidis further enhances its antibacterial resistance. However, whether genes related to biofilm formation affect the level of vertical transmission is still unclear. Here, S. Enteritidis mutants ΔcsgD, ΔcsgA, ΔbcsA, and ΔadrA were constructed from wild type strain C50041 (WT), and their biofilm-forming ability was determined by Crystal violet staining assay. Then the median lethal dose (LD₅₀) assay was performed to determine the effects of the selected genes on virulence. The bacterial load in eggs produced by infected laying hens via the intraperitoneal pathway or crop gavage was determined for evaluation of the vertical transmission. Crystal violet staining assay revealed that S. Enteritidis mutants ΔcsgD, ΔcsgA, and ΔbcsA, but not ΔadrA, impaired biofilm formation compared with WT strain. Furthermore, the LD₅₀ in SPF chickens showed that both the ΔcsgD and ΔbcsA mutants were less virulent compared with WT strain. Among the intraperitoneally infected laying hens, the WT strain-infected group had the highest percentage of bacteria-positive eggs (24.7%), followed by the ΔadrA group (16%), ΔcsgA group (9.9%), ΔbcsA group (4.5%), and ΔcsgD group (2.1%). Similarly, among the crop gavage chickens, the WT strain group also had the highest infection percentage in eggs (10.4%), followed by the ΔcsgA group (8.5%), ΔadrA group (7.5%), ΔbcsA group (1.9%), and ΔcsgD group (1.0%). Our results indicate that the genes csgD and bcsA help vertical transmission of S. Enteritidis in chickens.

Strategies to Improve Poultry Food Safety, a Landscape Review

Food safety remains a significant public health issue for the poultry industry. Foodborne pathogens can be in contact at all phases of poultry production, from initial hatch to processing and ultimately to retail and meal preparation. Salmonella and Campylobacter have been considered the primary foodborne pathogens associated with poultry. Both organisms are major causative agents of human foodborne illness. Limiting these pathogens in poultry production requires identifying their sources and routes of transmission. This involves the ability to isolate and precisely identify them using methodologies capable of discernment at the genome level. Interventions to reduce their occurrence in poultry production employ two basic strategies: prevention of establishment and elimination of already-established pathogens. This review provides an overview of current findings and prospects for further research on poultry food safety issues.

Phenotypic analyses of Salmonella enterica serovar Enteritidis strains isolated in the pre- and post-epidemic period in Brazil

Salmonella Enteritidis has caused, since the 1980s, a sustained epidemic of human infections in many countries. This study analyzed S. Enteritidis strains isolated before and after the epidemic period in Brazil regarding their capacities to survive to acid, oxidative, and high-temperature stresses, and capacity to grow in egg albumen. Moreover, the ability to invade human epithelial cells (Caco-2) and to survive inside human (U937) and chicken (HD11) macrophages was checked. Post-epidemic strains showed a better ability to survive after 10 min under acid stress at 37 °C (P ≤ 0.05). However, both groups of strains showed similar ability to survive after 1 h under acid stress at 37 °C and at 42 °C independently of the time of exposure. Similar ability was verified in both groups of strains regarding oxidative stress, growth in egg albumen, high-temperature stress, invasion to Caco-2 cells, and invasion and survival in macrophages. In conclusion, post-epidemic S. Enteritidis strains showed a better ability to survive under the acid stress found in the stomach, which might be an advantage to reach the intestine and colonize chickens and humans. However, both groups of strains did not differ significantly in the majority of the phenotypic tests analyzed in this study.

Research on the Effect of Pediococcus pentosaceus on Salmonella enteritidis-Infected Chicken

Salmonella enteritidis can cause significant morbidity and mortality in humans and economic loss in the animal industry. Improving the innate immunity is an effective method to prevent S. enteritidis infection. Pediococcus pentosaceus is a Gram-positive coccus which had probiotics properties. Numerous previously published studies reported that probiotics were beneficial to gut microbiota by changing the intestinal flora structure and inhibiting the harmful microbial growth to enhance the innate immunity. We investigated the immunological effects of P. pentosaceus on Salmonella-infected chickens by the following experiment. A total of 120 broilers from AA line were fed and divided into 2 groups (treated and control groups) for the experiment from day 1. The control group was fed with the basic diet, while the treated group was fed with the basic diet adding P. pentosaceus microcapsule with the bacterial concentration of 1 g/kg in the feed and bacterial counts 2.5 × 10⁹ CFU/g. All the birds were given with 0.5 ml of S. enteritidis bacterial suspension (10⁹ CFU/ml) through oral cavity at day 9. The number of dead birds was recorded and used in the analysis. The bacterial culture method and quantitative real-time PCR analysis were used to evaluate the effects of P. pentosaceus on chickens infected with S. enteritidis and to ascertain the mechanism of the effect. The results showed that the P. pentosaceus could restrain the pathogenicity of S. enteritidis and reduce the death rate from 44.4% to 23.3%. The flora in the caecum exhibited “rising-declining” trends, and the gene (TLR4, MyD88, TRAF6 NF-κB, IFN-β, TNF-a, IL6, and IL8) expression pattern was different between the experimental and control group. P. pentosaceus as a probiotic may competitively inhibit the growth of S. enteritidis and control the inflammatory response through regulating the gene expression which involved in the toll-like receptor pathway and inflammation pathway.

The Expanded Role of Roof-Rats (Rattus rattus) in Salmonella spp. Contamination of a Commercial Layer Farm in East Japan

Rodents serve as amplifiers of Salmonella infections in poultry flocks and can serve as a source of Salmonella contamination in the environment even after thorough cleaning and disinfection. This study aims to determine the dynamics of Salmonella occurrence in rodents and its relation to Salmonella contamination in the layer farm environment, including air dusts and eggs. From 2008 to 2017, roof rats (Rattus rattus), environmental swabs, air dusts, and eggs were collected from an intensive commercial layer farm in East Japan and were tested for Salmonella spp. using standard procedures. In roof rat samples, the Salmonella isolation rate was reached at 10% (95% confidence interval [CI] 8.1-21.9) in which Salmonella Corvallis, Salmonella Infantis, Salmonella Potsdam, and Salmonella Mbandaka were the frequent isolates from the cecal portion of the intestines. On the other hand, the prevalence rate of Salmonella in environmental swabs was at 5.1% (95% CI 2.2-7.4) while air dusts were at 0.9% (95% CI 0.2-1.8). It was observed that the prevalence of predominant Salmonella serotypes shifted over time; in roof rats, it was noted that Salmonella Potsdam gradually replaced Salmonella Infantis. In environmental swabs and eggs, Salmonella Corvallis and Salmonella Potsdam increased significantly while Salmonella Infantis became less frequent. In air dusts, Salmonella Corvallis was observed to decrease and Salmonella Potsdam became more common. Based on our findings, the role of roof rats in the epidemiology of Salmonella in layer farms was expanded from being a reservoir and an amplifier host into a shifting vessel of the most predominant serotypes.

Distribution of Salmonella Serovars in Humans, Foods, Farm Animals and Environment, Companion and Wildlife Animals in Singapore

We analyzed the epidemiological distribution of Salmonella serovars in humans, foods, animals and the environment as a One-Health step towards identifying risk factors for human salmonellosis. Throughout the 2012-2016 period, Salmonella ser. Enteritidis was consistently the predominating serovar attributing to >20.0% of isolates in humans. Other most common serovars in humans include Salmonella ser. Stanley, Salmonella ser. Weltevreden, Salmonella ser. Typhimurium and Salmonella ser. 4,5,12:b:-(dT+). S. Enteritidis was also the most frequent serovar found among the isolates from chicken/chicken products (28.5%) and eggs/egg products (61.5%) during the same period. In contrast, S. Typhimurium (35.2%) and Salmonella ser. Derby (18.8%) were prevalent in pork/pork products. S. Weltevreden was more frequent in seafood (19.2%) than others (≤3.0%). Most isolates (>80.0%) from farms, companion and wildlife animals belonged to serovars other than S. Enteritidis or S. Typhimurium. Findings demonstrate the significance of a One-Health investigative approach to understand the epidemiology Salmonella for more effective and integrated surveillance systems.

The correlated expression of immune and energy metabolism related genes in the response to Salmonella enterica serovar Enteritidis inoculation in chicken

Background

Salmonella enterica serovar Enteritidis (SE) is one of the food-borne pathogenic bacteria, which affects poultry production and poses severe threat to human health. The correlation of immune system and metabolism in chicken after SE inoculation is important but not clear. In the current study, we identified the expression of immune and energy metabolism related genes using quantitative PCR to evaluate the correlation between immune system and energy metabolism against SE inoculation in Jining Bairi chicken.

Results

ATP5G1, ATP5G3 and ND2 were significantly up-regulated at 1 dpi (day post inoculation), and ATP5E, ATP5G1, ATP5G3 were significantly down-regulated at 7 dpi (P < 0.05). IL-8 and IL-1β were significantly down-regulated at 1 dpi, IL-8 and IL-18 were significantly down-regulated at 3 dpi, IL-8 and BCL10 were significantly up-regulated at 7 dpi (P < 0.05).

Conclusions

These findings indicate that the correlation between immune and energy metabolism related genes gradually change with time points post SE inoculation, from one homeostasis to an opposite homeostasis with 3 dpi as a turning point. These results will pave the foundation for the relationship between immune system and energy metabolism in the response to SE inoculation in chicken.

Salmonella Enteritidis ghost vaccine carrying the hemagglutinin globular head (HA1) domain from H1N1 virus protects against salmonellosis and influenza in chickens

This study evaluated the attenuated Salmonella Enteritidis (SE) ghost strain JOL2114 (Δlon ΔcpxR Δasd), which displays on the bacterial surface the H1N1 hemagglutinin globular head portion (HA1; amino acid residues 63-286) on the bacterial surface for protective efficacy against Salmonella and H1N1 challenge in the chicken model, as the birds are the predominant reservoirs for both diseases. The ghost system enhanced the lysis process by converging two lysis processes found in bacteriophages: bacteriophage PhiX174 lysis gene E and holin-endolysin genes found in bacteriophage λ, complemented with accessory lysis-related proteins Rz/Rz1. The present lysis machinery resulted in complete lysis of host-attenuated SE strains in about 24 hrs of incubation under a non-permissible temperature of 42 °C in the absence of L-arabinose, an antisense inducer that blocks lysis gene expression during the growth phase. SE ghost JOL2114 surface display of HA1 was confirmed by Western blot analysis resulting in an immune-reactive band of 31 kDa in size. Chicken immunization via intramuscular and oral routes yielded both SE and HA1 antigen-specific immune responses. Protective humoral and cell-mediated immune responses were effectively elicited against both Salmonella and influenza challenge. This efficient strategy of ghost generation employs a dual system of phage lysis for biological generation of SE ghosts that preserves the surface antigenic architecture, offering a rapid and effective way to generate vaccines that could be deployed in urgent circumstances to protect against both Salmonella and influenza infection.

Salmonella Serotypes: A Novel Measure of Association with Foodborne Transmission

Most nontyphoidal Salmonella (NTS) illnesses in the United States are thought to be foodborne. However, transmission routes likely vary among the different serotypes. We developed a relative ranking of NTS serotypes according to the strength of their association with foodborne transmission. We used Laboratory-based Enteric Disease Surveillance data to estimate the proportion of infections for each Salmonella serotype reported from 1998 to 2015 and Foodborne Disease Outbreak Surveillance System data to calculate the proportion of foodborne outbreak-associated Salmonella illnesses caused by each serotype. We calculated the ratios of these proportions to create a foodborne relatedness (FBR) measure for each serotype. Of the top 20 serotypes, Saintpaul (2.14), Heidelberg (1.61), and Berta (1.48) had the highest FBR measures; Mississippi (0.01), Bareilly (0.13), and Paratyphi B variant L(+) tartrate(+) (0.20) had the lowest. The FBRs for the three most prevalent serotypes were 1.22 for Enteritidis, 0.77 for Typhimurium, and 1.16 for Newport. This method provides a quantitative approach to estimating the relative differences in the likelihood that an illness caused by a particular serotype was transmitted by food, which may aid in tailoring strategies to prevent Salmonella illnesses and guide future research into serotype-specific source attribution.

Identification of common highly expressed genes of Salmonella Enteritidis by in silico prediction of gene expression and in vitro transcriptomic analysis

Chickens are the reservoir host of Salmonella Enteritidis. Salmonella Enteritidis colonizes the gastro-intestinal tract of chickens and replicates within macrophages without causing clinically discernable illness. Persistence of S. Enteritidis in the hostile environments of intestinal tract and macrophages allows it to disseminate extra-intestinally to liver, spleen, and reproductive tract. Extra-intestinal dissemination into reproductive tract leads to contamination of internal contents of eggs, which is a major risk factor for human infection. Understanding the genes that contribute to S. Enteritidis persistence in the chicken host is central to elucidate the genetic basis of the unique pathobiology of this public health pathogen. The aim of this study was to identify a succinct set of genes associated with infection-relevant in vitro environments to provide a rational foundation for subsequent biologically-relevant research. We used in silico prediction of gene expression and RNA-seq technology to identify a core set of 73 S. Enteritidis genes that are consistently highly expressed in multiple S. Enteritidis strains cultured at avian physiologic temperature under conditions that represent intestinal and intracellular environments. These common highly expressed (CHX) genes encode proteins involved in bacterial metabolism, protein synthesis, cell-envelope biogenesis, stress response, and a few proteins with uncharacterized functions. Further studies are needed to dissect the contribution of these CHX genes to the pathobiology of S. Enteritidis in the avian host. Several of the CHX genes could serve as promising targets for studies towards the development of immunoprophylactic and novel therapeutic strategies to prevent colonization of chickens and their environment with S. Enteritidis.

Worldwide Epidemiology of Salmonella Serovars in Animal-Based Foods: a Meta-analysis

Salmonella spp. are among the most important foodborne pathogens and the third leading cause of human death among diarrheal diseases worldwide. Animals are the primary source of this pathogen, and animal-based foods are the main transmission route to humans. Thus, understanding the global epidemiology of Salmonella serovars is key to controlling and monitoring this bacterium. In this context, this study aimed to evaluate the prevalence and diversity of Salmonella enterica serovars in animal-based foods (beef, pork, poultry, and seafood) throughout the five continents (Africa, the Americas [North and Latin America], Asia, Europe, and Oceania). The meta-analysis consisted of a chemometric assessment (hierarchical cluster analysis and principal component analysis) to identify the main epidemiological findings, including the prevalence and diversity of the Salmonella serovars in each matrix. Regarding the serovar distribution, S Typhimurium presented a cosmopolitan distribution, reported in all four assessed matrices and continents; poultry continues to play a central role in the dissemination of the Enteritidis serovar to humans, and Anatum and Weltevreden were the most frequently found in beef and seafood, respectively. Additionally, we recommended careful monitoring of certain serovars, such as Derby, Agona, Infantis, and Kentucky. Finally, given the scientific data regarding the most frequently reported serovars and which matrices constitute the main vehicles for the transmission of this pathogen, control programs may be improved, and specific interventions may be implemented in an attempt to reduce the risk of this pathogen reaching humans.IMPORTANCE Salmonellosis is caused by Salmonella spp. and is the third leading cause of death among food-transmitted diseases. This pathogen is commonly disseminated in domestic and wild animals, and the infection's symptoms are characterized by acute fever, nausea, abdominal pain, and diarrhea. The animals are the primary source of salmonellae, and animal-based foods are the main transmission route to humans. Therefore, data collected from these sources could contribute to future global interventions for effective control and surveillance of Salmonella along the food chain. In light of this, the importance of our research is in identifying the prevalence of Salmonella serovars in four animal-based food matrices (pork, poultry, beef, and seafood) and to evaluate the importance that each matrix has as the primary source of this pathogen to humans.

The Salmonella Enteritidis TolC outer membrane channel is essential for egg white survival

Salmonella Enteritidis has developed the potential to contaminate eggs by surviving in the antimicrobial environment of the hen's egg white. This has led to a worldwide pandemic of foodborne salmonellosis infections in humans due to the consumption of contaminated eggs and egg-derived products. The molecular mechanisms of Salmonella Enteritidis egg white survival are not fully clear. Using in vivo expression technology and promoter-reporter fusions we showed that the promoter of the tolC gene, encoding the TolC outer membrane channel that is used by multidrug efflux pumps to export harmful molecules and to secrete bacterial products, is activated by egg white at the chicken body temperature. Using a Salmonella Enteritidis tolC deletion mutant we showed that TolC has an important role in egg white survival. Chromatographic separation techniques and subsequent testing of antimicrobial activities of separated egg white fractions led to the identification of ovotransferrin as the egg white antimicrobial factor which is capable of inhibiting growth of a tolC deletion strain but not the wild type strain. We provide evidence that TolC protects Salmonella Enteritidis against ovotransferrin-mediated growth inhibition in egg white.

Salmonella control in poultry flocks and its public health impact

An increase in confirmed human salmonellosis cases in the EU after 2014 triggered investigation of contributory factors and control options in poultry production. Reconsideration of the five current target serovars for breeding hens showed that there is justification for retaining Salmonella Enteritidis, Salmonella Typhimurium (including monophasic variants) and Salmonella Infantis, while Salmonella Virchow and Salmonella Hadar could be replaced by Salmonella Kentucky and either Salmonella Heidelberg, Salmonella Thompson or a variable serovar in national prevalence targets. However, a target that incorporates all serovars is expected to be more effective as the most relevant serovars in breeding flocks vary between Member State (MS) and over time. Achievement of a 1% target for the current target serovars in laying hen flocks is estimated to be reduced by 254,400 CrI95[98,540; 602,700] compared to the situation in 2016. This translates to a reduction of 53.4% CrI95[39.1; 65.7] considering the layer-associated human salmonellosis true cases and 6.2% considering the overall human salmonellosis true cases in the 23 MSs included in attribution modelling. A review of risk factors for Salmonella in laying hens revealed that overall evidence points to a lower occurrence in non-cage compared to cage systems. A conclusion on the effect of outdoor access or impact of the shift from conventional to enriched cages could not be reached. A similar review for broiler chickens concluded that the evidence that outdoor access affects the occurrence of Salmonella is inconclusive. There is conclusive evidence that an increased stocking density, larger farms and stress result in increased occurrence, persistence and spread of Salmonella in laying hen flocks. Based on scientific evidence, an impact of Salmonella control programmes, apart from general hygiene procedures, on the prevalence of Campylobacter in broiler flocks at the holding and on broiler meat at the end of the slaughter process is not expected.

Avian Toll-like receptor allelic diversity far exceeds human polymorphism: an insight from domestic chicken breeds

Immune genes show remarkable levels of adaptive variation shaped by pathogen-mediated selection. Compared to humans, however, population polymorphism in animals has been understudied. To provide an insight into immunogenetic diversity in birds, we sequenced complete protein-coding regions of all Toll-like receptor (TLR) genes with direct orthology between mammals and birds (TLR3, TLR4, TLR5 and TLR7) in 110 domestic chickens from 25 breeds and compared their variability with a corresponding human dataset. Chicken TLRs (chTLRs) exhibit on average nine-times higher nucleotide diversity than human TLRs (hTLRs). Increased potentially functional non-synonymous variability is found in chTLR ligand-binding ectodomains. While we identified seven sites in chTLRs under positive selection and found evidence for convergence between alleles, no selection or convergence was detected in hTLRs. Up to six-times more alleles were identified in fowl (70 chTLR4 alleles vs. 11 hTLR4 alleles). In chTLRs, high numbers of alleles are shared between the breeds and the allelic frequencies are more equal than in hTLRs. These differences may have an important impact on infectious disease resistance and host-parasite co-evolution. Though adaptation through high genetic variation is typical for acquired immunity (e.g. MHC), our results show striking levels of intraspecific polymorphism also in poultry innate immune receptors.

Transmission routes of ESBL/pAmpC producing bacteria in the broiler production pyramid, a literature review

Plasmid mediated Extended Spectrum Beta-Lactamase and AmpC Beta-Lactamase (ESBL/pAmpC) producing bacteria are resistant to beta-lactam antimicrobials and are widespread in humans, the environment and animals. Animals, especially broilers, are an important reservoir of ESBL/pAmpC producing bacteria. To control ESBL/pAmpC prevalence in broilers, transmission within the entire broiler production pyramid should be considered. This study, including 103 articles originating from two electronic databases, searched for evidence for possible routes of transmission of ESBL/pAmpC producing bacteria in the broiler production pyramid. Possible routes of transmission were categorised as 1) vertical between generations, 2) at hatcheries, 3) horizontal on farm, and 4) horizontal between farms and via the environment of farms. This review presents indications for transmission of ESBL/pAmpC producing bacteria for each of these routes. However, the lack of quantitative results in the literature did not allow an estimation of the relative contribution or magnitude of the different routes. Future research should be specifically targeted towards such information as it is crucial to guide reduction strategies for the spread of ESBL/pAmpC producing bacteria in the broiler production chain.

Comparative Genomic Analysis and Characterization of Two Salmonella enterica Serovar Enteritidis Isolates From Poultry With Notably Different Survival Abilities in Egg Whites

Salmonellaenterica serovar Enteritidis (Salmonella Enteritidis) is a globally important foodborne pathogen, and the contaminated chicken eggs are the major source of salmonellosis in humans. Salmonella Enteritidis strains are differentially susceptible to the hostile environment of egg whites. Strains with superior survival ability in egg whites are more likely to contaminate eggs and consequently infect humans. However, the genetic basis for this phenotype is unclear. We characterized two Salmonella Enteritidis strains isolated from chicken meat that had similar genetic backgrounds but large differences in survival ability in egg whites. Although genome comparisons indicated that the gene content and genomic synteny were highly conserved, variations including six insertions or deletions (INDELs) and 70 single nucleotide polymorphisms (SNPs) were observed between the two genomes. Of these, 38 variations including four INDELs and 34 non-synonymous SNPs (nsSNP) were annotated to result in amino acid substitutions or INDELs in coding proteins. These variations were located in 38 genes involved in lysozyme inhibition, vitamin biosynthesis, cell division and DNA damage response, osmotic and oxidative protection, iron-related functions, cell envelope maintenance, amino acid and carbohydrate metabolism, antimicrobial resistance, and type III secretion system. We carried out allelic replacements for two nsSNPs in bioC (biotin synthesis) and pliC (lysozyme inhibition), and two INDELs in ftsK and yqiJ (DNA damage response) by homologous recombination, and these replacements did not alter the bacterial survival ability in egg whites. However, the bacterial survival ability in egg whites was reduced when deletion mutation of the genes bioC and pliC occurred. This study provides initial correlations between observed genotypes and phenotypes and serves as an important caveat for further functional studies.