Re-thinking the chicken-Campylobacter jejuni interaction: a review

Diametral influence of deoxynivalenol (DON) and deepoxy-deoxynivalenol (DOM-1) on the growth of Campylobacter jejuni with consequences on the bacterial transcriptome

BACKGROUND

Deoxynivalenol (DON) is a type B trichothecene mycotoxin that is commonly found in cereals and grains worldwide. The presence of this fungal secondary-metabolite raises public-health concerns at both the agriculture and food industry level. Recently, we have shown that DON has a negative impact on gut integrity, a feature also noticed for Campylobacter (C.) jejuni. We further demonstrated that DON increased the load of C. jejuni in the gut and inner organs. In contrast, feeding the less toxic DON metabolite deepoxy-deoxynivalenol (DOM-1) to broilers reduced the Campylobacter load in vivo. Consequently, it can be hypothesized that DON and DOM-1 have a direct effect on the growth profile of C. jejuni. The aim of the present study was to further resolve the nature of this interaction in vitro by co-incubation and RNA-sequencing.

RESULTS

The co-incubation of C. jejuni with DON resulted in significantly higher bacterial growth rates from 30 h of incubation onwards. On the contrary, the co-incubation of C. jejuni with DOM-1 reduced the CFU counts, indicating that this DON metabolite might contribute to reduce the burden of C. jejuni in birds, altogether confirming in vivo data. Furthermore, the transcriptomic profile of C. jejuni following incubation with either DON or DOM-1 differed. Co-incubation of C. jejuni with DON significantly increased the expression of multiple genes which are critical for Campylobacter growth, particularly members of the Flagella gene family, frr (ribosome-recycling factor), PBP2 futA-like (Fe3+ periplasmic binding family) and PotA (ATP-binding subunit). Flagella are responsible for motility, biofilm formation and host colonization, which may explain the high Campylobacter load in the gut of DON-fed broiler chickens. On the contrary, DOM-1 downregulated the Flagella gene family and upregulated ribosomal proteins.

CONCLUSION

The results highlight the adaptive mechanisms involved in the transcriptional response of C. jejuni to DON and its metabolite DOM-1, based on the following effects: (a) ribosomal proteins; (b) flagellar proteins; (c) engagement of different metabolic pathways. The results provide insight into the response of an important intestinal microbial pathogen against DON and lead to a better understanding of the luminal or environmental acclimation mechanisms in chickens.

Short Variable Regions flaA Gene (SVR-flaA) Diversity and Virulence Profile of Multidrug-Resistant Campylobacter from Poultry and Poultry Meat in India

Human gastrointestinal infections caused by Campylobacter species is the second most important foodborne illness after salmonellosis worldwide. Poultry represent one of the main sources of Campylobacter organisms. In the present study, the short variable region of flagellin gene (SVR-flaA) typing was carried out to determine the variation among the circulating strains of Campylobacter jejuni and Campylobacter coli. The C. jejuni and C. coli isolated from poultry and poultry meat were screened for the presence of virulence determinants like cadF, flaA, cdtB, and wlaN gene. The screening for wlaN gene is crucial in view of the fact that most patients with Guillian Barre's (GB) syndrome with a preceding history of diarrheal illness have been found to harbor wlaN gene-positive C jejuni strains. Out of the 200 samples comprising poultry meat and cloacal swabs, 21.5% of samples were found to harbor Campylobacter spp. of which 2.5% were Campylobacter jejuni, and 19% were confirmed as Campylobacter coli. The cadF, flaA, cdtB virulence genes were detected in all the Campylobacter spp. isolated in the present study. The presence of the wlaN gene in the Campylobacter jejuni isolated in the present study may pose a public health threat with long-term human health implications. The SVR-flaA typing of twelve Campylobacter isolates obtained in the present study revealed that Campylobacter coli flaA sequence OL471375 is a new strain with a novel allele type 1,675 and peptide sequence 5 which stands deposited in pubMLST database for Campylobacter. The other flaA-SVR gene sequences identified in this study were OL471369, OL471370, OL471371, OL471372, OL471373, and OL471374. Among twelve Campylobacter spp., three distinct DdeI-RFLP patterns were observed, each varying in size from 100 to 1,000 base pairs. Antimicrobial profiling of the Campylobacter spp. isolated in the present study revealed that 50% of the strains were multidrug resistant. All the Campylobacter spp. were resistant to ciprofloxacin (CIP), ampicillin (AMP), penicillin (PEN), and nalidixic acid (NAL) whereas 57.1% of strains were resistant to tetracycline (TET) and erythromycin (ERY) 28% to amoxicillin (AMX) and enrofloxacin (ENO), 85% to amikacin (AMK). The high degree of resistance to fluoroquinolones observed in the present study is crucial in view of fluoroquinolones being drugs of choice for the treatment of human Campylobacter infections.

In vitro investigations on interference of selected probiotic candidates with Campylobacter jejuni adhesion and invasion of primary chicken derived cecal and Caco-2 cells

BACKGROUND

Campylobacter (C.) jejuni is one of the most important bacterial foodborne pathogens worldwide. Probiotics such as Lactobacillus or Bacillus species are considered one option for reducing the colonization rate and magnitude in poultry, the most frequent source of human infections. Due to the lack of suitable avian in vitro models such as chicken intestinal cell lines, especially those derived from the cecum, most in vitro studies on C. jejuni host interaction have been conducted with human intestinal cell lines. In this study, we compared C. jejuni-cell interactions between primary chicken cecal cells and the human intestinal cell line Caco-2, which is derived from colorectal adenocarcinoma, and investigated possible interfering effects of selected probiotic candidates.

RESULTS

We detected differences in adhesion and invasion between the two tested gut cell types and between different C. jejuni strains. The probiotic inhibition of C. jejuni adhesion and invasion of human and avian gut cells was affected by host cell type, investigated C. jejuni strain and time points of probiotic treatment. Additionally, our results suggest a possible correlation between C. jejuni invasion and the detected increase in IL-6 mRNA expression.

CONCLUSIONS

Our results indicate distinct differences between avian and human gut cells in their interaction with C. jejuni. Therefore, data obtained in one host species on C. jejuni-host interaction may not easily be transferrable to another one. The factors influencing the variable efficacy of probiotic intervention in chicken and human derived cells should be investigated further.

Proteome profiling of Campylobacter jejuni 81-176 at 37 °C and 42 °C by label-free mass spectrometry

BACKGROUND

The main natural reservoir for Campylobacter jejuni is the avian intestinal tract. There, C. jejuni multiplies optimally at 42 °C - the avian body temperature. After infecting humans through oral intake, the bacterium encounters the lower temperature of 37 °C in the human intestinal tract. Proteome profiling by label-free mass spectrometry (DIA-MS) was performed to examine the processes which enable C. jejuni 81-176 to thrive at 37 °C in comparison to 42 °C. In total, four states were compared with each other: incubation for 12 h at 37 °C, for 24 h at 37 °C, for 12 h at 42 °C and 24 h at 42 °C.

RESULTS

It was shown that the proteomic changes not only according to the different incubation temperature but also to the length of the incubation period were evident when comparing 37 °C and 42 °C as well as 12 h and 24 h of incubation. Altogether, the expression of 957 proteins was quantifiable. 37.1 - 47.3% of the proteins analyzed showed significant differential regulation, with at least a 1.5-fold change in either direction (i.e. log2 FC ≥ 0.585 or log2 FC ≤ -0.585) and an FDR-adjusted p-value of less than 0.05. The significantly differentially expressed proteins could be arranged in 4 different clusters and 16 functional categories.

CONCLUSIONS

The C. jejuni proteome at 42 °C is better adapted to high replication rates than that at 37 °C, which was in particular indicated by the up-regulation of proteins belonging to the functional categories "replication" (e.g. Obg, ParABS, and NapL), "DNA synthesis and repair factors" (e.g. DNA-polymerase III, DnaB, and DnaE), "lipid and carbohydrate biosynthesis" (e.g. capsular biosynthesis sugar kinase, PrsA, AccA, and AccP) and "vitamin synthesis, metabolism, cofactor biosynthesis" (e.g. MobB, BioA, and ThiE). The relative up-regulation of proteins with chaperone function (GroL, DnaK, ClpB, HslU, GroS, DnaJ, DnaJ-1, and NapD) at 37 °C in comparison to 42 °C after 12 h incubation indicates a temporary lower-temperature proteomic response. Additionally the up-regulation of factors for DNA uptake (ComEA and RecA) at 37 °C compared to 42 °C indicate a higher competence for the acquisition of extraneous DNA at human body temperature.

Gallnut tannic acid alleviates gut damage induced by Salmonella pullorum in broilers by enhancing barrier function and modulating microbiota

Pullorum disease (PD) is a bacterial infection caused by Salmonella pullorum (S. pullorum) that affects poultry. It is highly infectious and often fatal. Antibiotics are currently the mainstay of prophylactic and therapeutic treatments for PD, but their use can lead to the development of resistance in pathogenic bacteria and disruption of the host's intestinal flora. We added neomycin sulfate and different doses of tannic acid (TA) to the drinking water of chicks at 3 days of age and infected them with PD by intraperitoneal injection of S. pullorum at 9 days of age. We analyzed intestinal histopathological changes and the expression of immune-related genes and proteins by using the plate smear method, histological staining, real-time fluorescence quantitative PCR, ELISA kits, and 16S rRNA Analysis of intestinal flora. The results demonstrate that S. pullorum induces alterations in the immune status and impairs the functionality of the liver and intestinal barrier. We found that tannic acid significantly ameliorated S. pullorum-induced liver and intestinal damage, protected the intestinal physical and chemical barriers, restored the intestinal immune barrier function, and regulated the intestinal flora. Our results showed that TA has good anti-diarrhoeal, growth-promoting, immune-regulating, intestinal barrier-protecting and intestinal flora-balancing effects, and the best effect was achieved at an additive dose of 0.2%.

Investigation of Potential Gut Health Biomarkers in Broiler Chicks Challenged by Campylobacter jejuni and Submitted to a Continuous Water Disinfection Program

The exploration of novel biomarkers to assess poultry health is of paramount importance, not only to enhance our understanding of the pathogenicity of zoonotic agents but also to evaluate the efficacy of novel treatments as alternatives to antibiotics. The present study aimed to investigate potential gut health biomarkers in broiler chicks challenged by Campylobacter jejuni and subjected to a continuous water disinfection program. A total of 144 one-day-old hatched broiler chicks were randomly allocated to four treatment groups with four replicates each, according to the following experimental design: Group A received untreated drinking water; Group B received drinking water treated with 0.01-0.05% v/v Cid 2000™ (hydrogen peroxide, acetic acid and paracetic acid); Group C was challenged by C. jejuni and received untreated drinking water; and Group D was challenged by C. jejuni and received drinking water treated with 0.01-0.05% v/v Cid 2000™. The use of Cid 2000™ started on day 1 and was applied in intervals until the end of the experiment at 36 days, while the C. jejuni challenge was applied on day 18. Potential biomarkers were investigated in serum, feces, intestinal tissue, intestinal content, and liver samples of broilers. Statistical analysis revealed significant increases (p < 0.001) in serum cortisol levels in C. jejuni-challenged broilers. Serum fluorescein isothiocyanate dextran (FITC-d) increased significantly (p = 0.004) in broilers challenged by C. jejuni and treated with drinking water disinfectant, while fecal ovotransferrin concentration also increased significantly (p < 0.001) in broilers that received the drinking water disinfectant alone. The gene expression levels of occludin (p = 0.003) and mucin-2 (p < 0.001) were significantly upregulated in broilers challenged by C. jejuni, while mucin-2 significantly increased in birds that were challenged and received the drinking water disinfectant (p < 0.001). TLR-4 expression levels were significantly (p = 0.013) decreased in both groups that received the drinking water disinfectant, compared to the negative control group. Finally, the C. jejuni challenge significantly increased (p = 0.032) the crypt depth and decreased (p = 0.021) the villus height-to-crypt-depth ratio in the ileum of birds, while the tested disinfectant product increased (p = 0.033) the villus height in the jejunum of birds. Furthermore, the counts of C. jejuni in the ceca of birds (p = 0.01), as well as its translocation rate to the liver of broilers (p = 0.001), were significantly reduced by the addition of the water disinfectant. This research contributes to novel insights into the intricate interplay of water disinfection and/or C. jejuni challenge with potential intestinal biomarkers. In addition, it emphasizes the need for continued research to unveil the underlying mechanisms, expands our understanding of broiler responses to these challenges and identifies breakpoints for further investigations.

Global Acetylomics of Campylobacter jejuni Shows Lysine Acetylation Regulates CadF Adhesin Processing and Human Fibronectin Binding

Lysine acetylation (KAc) is a reversible post-translational modification (PTM) that can alter protein structure and function; however, specific roles for KAc are largely undefined in bacteria. Acetyl-lysine immunoprecipitation and LC-MS/MS identified 5567 acetylated lysines on 1026 proteins from the gastrointestinal pathogen Campylobacter jejuni (∼63% of the predicted proteome). KAc was identified on proteins from all subcellular locations, including the outer membrane (OM) and extracellular proteins. Label-based LC-MS/MS identified proteins and KAc sites during growth in 0.1% sodium deoxycholate (DOC, a component of gut bile salts). 3410 acetylated peptides were quantified, and 784 (from 409 proteins) were differentially abundant in DOC growth. Changes in KAc involved multiple pathways, suggesting a dynamic role for this PTM in bile resistance. As observed elsewhere, we show KAc is primarily nonenzymatically mediated via acetyl-phosphate; however, the deacetylase CobB also contributes to a global elevation of this modification in DOC. We observed several multiply acetylated OM proteins and altered DOC abundance of acetylated peptides in the fibronectin (Fn)-binding adhesin CadF. We show KAc reduces CadF Fn binding and prevalence of lower mass variants. This study provides the first system-wide lysine acetylome of C. jejuni and contributes to our understanding of KAc as an emerging PTM in bacteria.

First report of phenotypic and genotypic (blaOXA-61) beta-lactam resistance in Campylobacter jejuni from broilers in Indonesia

Background and Aim

Campylobacter is a zoonotic bacterium that is a major source of foodborne diseases. In humans, most cases of campylobacteriosis are caused by Campylobacter jejuni. Poultry is the main reservoir of Campylobacter for humans, because Campylobacter is part of the normal flora of the digestive tract of poultry. Antimicrobial resistance to several antibiotics in Campylobacter isolated from humans and food animals has increased rapidly. Beta-lactam is an antibiotic with a high prevalence of resistance in Campylobacter. This study aimed to investigate phenotypic and genotypic (blaOXA-61) beta-lactam resistance in C. jejuni from broilers in Indonesia.

Materials and Methods

A total of 100 samples of broiler intestinal contents were obtained from 10 broiler farms in Pasuruan Regency, Indonesia. Campylobacter jejuni was identified using conventional and polymerase chain reaction (PCR)-based methods. Phenotypic detection of beta-lactam resistance was performed using an antimicrobial susceptibility test with antibiotic disks of aztreonam, ampicillin, and amoxicillin-clavulanic acid. Genotypic detection by PCR was performed using the blaOXA-61 gene, which encodes beta-lactamase.

Results

Campylobacter jejuni was identified in 23% of the samples. Phenotypically, 100% (23/23) and 73.9% (17/23) C. jejuni isolates had high resistance to aztreonam and ampicillin, respectively, but all isolates were susceptible to amoxicillin-clavulanic acid. Genotypically, all isolates carried blaOXA-61, indicated by the presence of a 372-bp PCR product.

Conclusion

Campylobacter jejuni is highly resistant to beta-lactams and is a serious threat to human health. Resistance to beta-lactams should be monitored because beta-lactamase genes can be transferred between bacteria. Public awareness must also be increased on the importance of using antibiotics rationally in humans and animals.

Screening of Potential Probiotic Lactobacillaceae and Their Improvement of Type 2 Diabetes Mellitus by Promoting PI3K/AKT Signaling Pathway in db/db Mice

The study aimed to isolate Lactobacillaceae strains with in vitro hypoglycemic activity and probiotic properties and to determine their antidiabetic abilities in vivo. Lactiplantibacillus plantarum 22, L. plantarum 25, Limosilactobacillus fermentum 11, and L. fermentum 305 with high in vitro hypoglycemic activity were screened from 23 strains of Lactobacillaceae isolated from human feces and identified by 16S rDNA sequencing. The fasting blood glucose (FBG) of the mice was recorded weekly. After 12 weeks, liver, kidney, and pancreas tissues were stained with hematoxylin and eosin (H&E) to observe histomorphology; the inflammatory factors were assayed by Quantitative Real-time PCR; PI3K and AKT were measured by Western blot; the short-chain fatty acids (SCFAs) were determined by LC-MS/MS. Inhibitory activities of L. plantarum 22, L. plantarum 25, L. fermentum 11, and L. fermentum 305 against α-amylase were 62.29 ± 0.44%, 51.81 ± 3.65%, 58.40 ± 1.68%, and 57.48 ± 5.04%, respectively. Their inhibitory activities to α-glucosidase were 14.89 ± 0.38%, 15.32 ± 0.89%, 52.63 ± 3.07%, and 51.79 ± 1.13%, respectively. Their survival rate after simulated gastrointestinal test were 12.42 ± 2.84%, 9.10 ± 1.12%, 5.86 ± 0.52%, and 8.82 ± 2.50% and their adhesion rates to Caco-2 cell were 6.09 ± 0.39%, 6.37 ± 0.28%, 6.94 ± 0.27%, and 6.91 ± 0.11%, respectively. The orthogonal tests of bacterial powders of the four strains showed that the maximum inhibitory activities to α-amylase and α-glucosidase were 93.18 ± 1.19% and 75.33 ± 2.89%, respectively. The results showed that the mixture of Lactobacillaceae could lower FBG, reduce inflammation, and liver, kidney, and pancreas damage, promote PI3K/AKT signaling pathway, and increase the content of SCFAs. The combination of L. plantarum 22, L. plantarum 25, L. fermentum 11, and L. fermentum 305 can potentially improve type 2 diabetes mellitus (T2DM).

Bacteriophage cocktail application for Campylobacter mitigation - from in vitro to in vivo

BACKGROUND

Effective strategies are urgently needed to control Campylobacteriosis, one of the most important foodborne gastrointestinal diseases worldwide. Administering bacteriophages (phages) is under evaluation as a possible intervention strategy in primary poultry production to reduce the public health risk of human infection. A major challenge is the translation of results from small-scale animal studies to large broiler flocks. In this study, the in vitro lytic activity of 18 Campylobacter-specific group II phages and 19 group III phages were examined singly, and in different combinations from the same group and from both groups using a planktonic killing assay. Based on these results, a combination of phage NCTC 12,673 (group III) and vB_CcM-LmqsCPL1/1 (group II) was selected for in vivo application in a seeder bird model to study its effectiveness under conditions as close as possible to field conditions. One hundred eighty Ross 308 broiler chickens were divided into a control and a treatment group. Ten days post hatch, seeder birds were orally inoculated with the C. jejuni target strain. Phages were administered via drinking water at a total concentration of 107 PFU/mL four, three, and two days before necropsy.

RESULTS

Combining group II and group III phages resulted in significantly higher in vitro growth inhibition against the C. jejuni target strain BfR-CA-14,430 than single application or combinations of phages from the same group. The results of the animal trial showed that the application of the two phages significantly reduced Campylobacter counts in cloacal swabs. At necropsy, Campylobacter counts in colonic content of the treatment group were significantly reduced by 2 log10 units compared to the control group.

CONCLUSIONS

We demonstrated that combining phages of groups II and III results in significantly increased lytic activities. The in vitro results were successfully translated into practical application in a study design close to field conditions, providing new data to apply phages in conventional broiler flocks in the future. Phage application reduced the fecal Campylobacter excretion and Campylobacter concentrations in the colon of broilers.

An Overview of the Use and Applications of Limosilactobacillus fermentum in Broiler Chickens

The implementation of government regulations on antibiotic use, along with the public's concern for drug resistance, has strengthened interest in developing alternatives not only aimed at preserving animal production but also at reducing the effects of pathogenic infections. Probiotics, in particular, are considered microorganisms that induce health benefits in the host after consumption of adequate amounts; they have been established as a potential strategy for improving growth, especially by stimulating intestinal homeostasis. Probiotics are commonly associated with lactic acid bacteria, and Limosilactobacillus fermentum is a well-studied species recognized for its favorable characteristics, including adhesion to epithelial cells, production of antimicrobial compounds, and activation of receptors that prompt the transcription of immune-associated genes. Recently, this species has been used in animal production. Different studies have shown that the application of L. fermentum strains not only improves the intestinal ecosystem but also reduces the effects caused by potentially pathogenic microorganisms. These studies have also revealed key insights into the mechanisms behind the actions exerted by this probiotic. In this manuscript, we aim to provide a concise overview of the effects of L. fermentum administration on broiler chicken health and performance.

Investigation of the Effect of Three Commercial Water Acidifiers on the Performance, Gut Health, and Campylobacter jejuni Colonization in Experimentally Challenged Broiler Chicks

This study investigated the effect of three commercial water acidifiers on the performance, gut health, and C. jejuni colonization in experimentally challenged broiler chicks. A total of 192 one-day-old broiler chicks (Ross 308^®) were randomly allocated into 6 treatment groups with 4 replicates according to the following experimental design: group A, birds were not challenged and received tap water; group B, birds were challenged and received tap water; groups C, D, E, and F, birds were challenged and received tap water treated with 0.1% v/v SPECTRON^®, with 0.1-0.2% v/v ProPhorce™ SA Exclusive, with 0.1-0.2% v/v Premium acid, and with 0.1-0.2% v/v Salgard^® Liquid, respectively. The continuous water acidification evoked undesirable effects on broilers' performance and to an increased number of birds with ulcers and erosions in the oral cavity and the upper esophageal area. ProPhorce™ SA Exclusive and Premium acid significantly reduced the C. jejuni counts in the crop, whereas Salgard^® Liquid significantly reduced the C. jejuni counts in the ceca of birds. At slaughter age, only Premium acid significantly reduced C. jejuni counts in the ceca of birds. All the tested products ameliorated the changes induced by C. jejuni infection in the pH in the ceca of birds. It can be concluded that besides the effectiveness of the tested products in controlling C. jejuni in broilers, their continuous application evoked undesirable effects on broilers' performance, leading to the need to modify the dosage scheme in future investigations.

The Development of Gut Microbiota and Its Changes Following C. jejuni Infection in Broilers

The gut is home to more than millions of bacterial species. The gut bacteria coexist with the host in a symbiotic relationship that can influence the host’s metabolism, nutrition, and physiology and even module various immune functions. The commensal gut microbiota plays a crucial role in shaping the immune response and provides a continuous stimulus to maintain an activated immune system. The recent advancements in high throughput omics technologies have improved our understanding of the role of commensal bacteria in developing the immune system in chickens. Chicken meat continues to be one of the most consumed sources of protein worldwide, with the demand expected to increase significantly by the year 2050. Yet, chickens are a significant reservoir for human foodborne pathogens such as Campylobacter jejuni. Understanding the interaction between the commensal bacteria and C. jejuni is essential in developing novel technologies to decrease C. jejuni load in broilers. This review aims to provide current knowledge of gut microbiota development and its interaction with the immune system in broilers. Additionally, the effect of C. jejuni infection on the gut microbiota is addressed.

Campylobacter jejuni infection induces dynamic expression of avian host defense peptides in vitro and in vivo

Campylobacter jejuni is considered as the leading cause of worldwide foodborne bacterial gastroenteritis. Chicken is the main reservoir of C. jejuni. Avian innate immune responses to C. jejuni remain poorly defined. Chicken host defense peptides (HDPs) are the major components of avian innate immune system. This study aimed to characterize the chicken HDPs responses to C. jejuni in vitro and in vivo. In the HD11 macrophage cell line, the HDPs, including AvBD1-2, CATH1-3, AvBD7, AvBD4, and AvBD6, were relatively higher expressed in untreated cells, whereas the expressions were suppressed after C. jejuni infection. In contrast, C. jejuni infection significantly increased the expression of the lower expressed HDPs, such as AvBD3, AvBD5, AvBD8-14, and CATHB1, in untreated cells. In the chicken challenge experiment, the immune tissues of spleens and cecal tonsils were collected from C. jejuni-infected and uninfected chickens at 1, 3 and 15 day post inoculation (DPI). In spleens of C. jejuni-infected chickens, only AvBD14 expression was elevated at 1 DPI. The majority of avian HDPs were significantly up-regulated at 3 DPI and dramatically decreased to the levels of uninfected controls at 15 DPI. In chicken cecal tonsils, only AvBD9 and AvBD14 were significantly up-regulated at 1 DPI with C. jejuni infection. Collectively, C. jejuni infection induced dynamic expression of chicken HDPs in both macrophage HD11 and immune tissues of chickens. Suppression of chicken HDPs expression may be an evasion strategy of C. jejuni for persistent colonization in chicken intestine by circumventing the chicken immune system.

Research Note: Analysis of immune responses in broilers after vaccination against Campylobacter jejuni

Campylobacter infections traced mainly to poultry products are major bacterial foodborne zoonoses. Among the many control strategies evaluated at primary poultry level to reduce these infections, vaccination could be a solution, but no effective vaccines are available to date. A better understanding of the immune mechanisms involved in protection against Campylobacter would be helpful for designing novel vaccine strategies. The present study was designed to analyze in more depth the immune responses developed in broilers in order to potentially identify which immune parameters may be important for establishing protection against Campylobacter by comparing the immune responses obtained here with those obtained in a previous study performed on vaccinated specific-pathogen-free Leghorn chickens that presented a partial reduction of Campylobacter after experimental challenge. The protection against Campylobacter colonization was evaluated at different time points over 40 d of rearing, by measuring specific IgY levels in serum and IgA antibodies in bile reflecting the systemic and mucosal humoral responses respectively and the relative expressions of 9 cecal immune marker genes (cytokines and antimicrobial peptides), which reflect the innate and cellular immune responses. Despite no reduction of Campylobacter in the cecum, a systemic immune response over time characterized by the production of specific anti-flagellin IgY was observed, in addition to upregulation of the antimicrobial peptide avian β-defensin (AvBD) 12 gene expression in the cecum of vaccinated broilers compared with the placebo group. However, the levels of specific anti-flagellin mucosal IgA antibodies in the bile as well as the relative expression of other cecal cytokines studied was underexpressed in the vaccinated group or similar in both groups.

Conformational dynamics and putative substrate extrusion pathways of the N-glycosylated outer membrane factor CmeC from Campylobacter jejuni

The outer membrane factor CmeC of the efflux machinery CmeABC plays an important role in conferring antibiotic and bile resistance to Campylobacter jejuni. Curiously, the protein is N-glycosylated, with the glycans playing a key role in the effective function of this system. In this work we have employed atomistic equilibrium molecular dynamics simulations of CmeC in a representative model of the C. jejuni outer membrane to characterise the dynamics of the protein and its associated glycans. We show that the glycans are more conformationally labile than had previously been thought. The extracellular loops of CmeC visit the open and closed states freely suggesting the absence of a gating mechanism on this side, while the narrow periplasmic entrance remains tightly closed, regulated via coordination to solvated cations. We identify several cation binding sites on the interior surface of the protein. Additionally, we used steered molecular dynamics simulations to elucidate translocation pathways for a bile acid and a macrolide antibiotic. These, and additional equilibrium simulations suggest that the anionic bile acid utilises multivalent cations to climb the ladder of acidic residues that line the interior surface of the protein.

Poor body condition is associated with lower hippocampal plasticity and higher gut methanogen abundance in adult laying hens from two housing systems

It is still unclear which commercial housing system provides the best quality of life for laying hens. In addition, there are large individual differences in stress levels within a system. Hippocampal neurogenesis or plasticity may provide an integrated biomarker of the stressors experienced by an individual. We selected 12 adult hens each with good and poor body condition (based on body size, degree of feather cover and redness of the comb) from a multi-tier free range system containing H&N strain hens, and from an enriched cage system containing Hy-Line hens (n = 48 total). Immature neurons expressing doublecortin (DCX) were quantified in the hippocampus, contents of the caecal microbiome were sequenced, and expression of inflammatory cytokines was measured in the spleen. DCX⁺ cell densities did not differ between the housing systems. In both systems, poor condition hens had lower DCX⁺ cell densities, exhibited elevated splenic expression of interleukin-6 (IL6) mRNA, and had a higher relative caecal abundance of methanogenic archea Methanomethylophilaceae. The findings suggest poor body condition is an indicator that individual hens have experienced a comparatively greater degree of cumulative chronic stress, and that a survey of the proportion of hens with poor body conditions might be one way to evaluate the impact of housing systems on hen welfare.

Novel strategies to improve chicken performance and welfare by unveiling host-microbiota interactions through hologenomics

Fast optimisation of farming practices is essential to meet environmental sustainability challenges. Hologenomics, the joint study of the genomic features of animals and the microbial communities associated with them, opens new avenues to obtain in-depth knowledge on how host-microbiota interactions affect animal performance and welfare, and in doing so, improve the quality and sustainability of animal production. Here, we introduce the animal trials conducted with broiler chickens in the H2020 project HoloFood, and our strategy to implement hologenomic analyses in light of the initial results, which despite yielding negligible effects of tested feed additives, provide relevant information to understand how host genomic features, microbiota development dynamics and host-microbiota interactions shape animal welfare and performance. We report the most relevant results, propose hypotheses to explain the observed patterns, and outline how these questions will be addressed through the generation and analysis of animal-microbiota multi-omic data during the HoloFood project.

Comparing effects of natural betaine and betaine hydrochloride on gut physiology in broiler chickens

Betaine is a well-known component of poultry diets with various effects on nutritional physiology. For example, increased water retention due to the osmolytic effect of betaine increases the volume of the cell, thereby accelerating the anabolic activity, integrity of cell membrane, and overall performance of the bird. Betaine is a multifunctional component (trimethyl derivative) acting as the most efficient methyl group donor and as an organic osmolyte, which can directly influence the gastrointestinal tract integrity, functionality, and health. So far, nothing is known about the effect of betaine on the intestinal barrier in chickens. In addition, little is known about comparing natural betaine with its synthetic form. Therefore, an animal study was conducted to ascertain the effects of betaine supplementation (natural and synthetic) on performance and intestinal physiological responses of broilers. One hundred and five 1-day-old broiler chicks were randomly assigned into 3 groups with 35 birds each: control, natural betaine (1 kg active natural (n)-betaine/ton of feed) and synthetic (syn)-betaine‐HCL (1 kg active betaine /ton of feed). Histological assessment showed lower jejunal crypt depth and villi height/crypt depth ratio in syn-betaine-HCL group compared with natural n-betaine fed birds. Furthermore, it was found that syn-betaine-HCL negatively affects the integrity of the intestine by increasing the intestinal paracellular permeability in both jejunum and cecum as evidenced by a higher mannitol flux. Additionally, syn-betaine-HCl significantly upregulated the IFN-γ mRNA expression at certain time points, which could promote intestinal permeability, as it plays an important role in intestinal barrier dysfunction. Body weight (BW) and body weight gain (BWG) did not differ (P > 0.05) between the control birds and birds supplemented with syn-betaine‐HCL. However, the BW and BWG were significantly (P < 0.05) improved by the dietary inclusion of n-betaine compared with other treatments. Altogether, the dietary inclusion of n-betaine had a positive effect on performance and did not negatively affect gut paracellular permeability. Furthermore, our results show that syn-betaine-HCl induces changes in the intestine, indicating an alteration of the intestinal histology and permeability. Thus, natural or synthetic betaine has different effects, which needs to be considered when using them as a feed supplement.

Effects of fulvic acid on growth performance, serum index, gut microbiota, and metabolites of Xianju yellow chicken

Fulvic acid (FA) is a mixture of polyphenolic acid compounds extracted from humus, peat, lignite, and aquatic environments; it is used in traditional medicine to treat digestive tract diseases. The purpose of the present study was to investigate the effect of FA on growth performance, inflammation, intestinal microbiota, and metabolites in Xianju yellow chicken. The 240 Xianju yellow chickens (age, 524 days) included were randomly categorized into 4 treatments with 6 replicates per treatment and 10 birds per replicate. Birds received a basal diet or a diet supplemented with 500, 1,000, or 1,500 mg/kg of FA, for a period of 42 days. Dietary supplementation of FA improved average daily gain (ADG) and feed conversion ratio (FCR) (P > 0.05). Compared with the control group, the serum level of TNF-α in birds supplemented with FA was significantly decreased (P < 0.05), and that of IL-2 was significantly increased after administration of 1,500 mg/kg FA (P < 0.05). Analysis of gut microbiota indicated that FA reduced the relative abundance of genus Mucispirillum, Anaerofustis, and Campylobacter, but enriched genus Lachnoclostridium, Subdoligranulum, Sphaerochaeta, Oscillibacter, and Catenibacillus among others. Untargeted metabolomic analyses revealed that FA increased 7-sulfocholic acid, but reduced the levels of Taurochenodeoxycholate-7-sulfate, LysoPC 20:4 (8Z, 11Z, 14Z, 17Z), LysoPC 18:2, Phosphocholine and other 13 metabolites in the cecum. The results demonstrated that FA may potentially have a significant positive effect on the growth performance and immune function of Xianju yellow chicken through the modulation of the gut microbiota.

The effect of Campylobacter jejuni and Campylobacter coli colonization on the gut morphology, functional integrity, and microbiota composition of female turkeys

BACKGROUND

Campylobacter (C.) species are the most common bacterial cause of foodborne diarrhea in humans. Despite colonization, most animals do not show clinical signs, making recognition of affected flocks and disruption of the infection chain before slaughter challenging. Turkeys are often cocolonized with C. jejuni and C. coli. To understand the pathogen-host-interaction in the context of two different Campylobacter species, we compared the colonization patterns and quantities in mono- and co-colonized female commercial turkeys. In three repeated experiments we investigated the impact on gut morphology, functional integrity, and microbiota composition as parameters of gut health at seven, 14, and 28 days post-inoculation.

RESULTS

Despite successful Campylobacter colonization, clinical signs or pathological lesions were not observed. C. coli persistently colonized the distal intestinal tract and at a higher load compared to C. jejuni. Both strains were isolated from livers and spleens, occurring more frequently in C. jejuni- and co-inoculated turkeys. Especially in C. jejuni-positive animals, translocation was accompanied by local heterophil infiltration, villus blunting, and shallower crypts. Increased permeability and lower electrogenic ion transport of the cecal mucosa were also observed. A lower relative abundance of Clostridia UCG-014, Lachnospiraceae, and Lactobacillaceae was noted in all inoculated groups compared to controls.

CONCLUSIONS

In sum, C. jejuni affects gut health and may interfere with productivity in turkeys. Despite a higher cecal load, the impact of C. coli on investigated parameters was less pronounced. Interestingly, gut morphology and functional integrity were also less affected in co-inoculated animals while the C. jejuni load decreased over time, suggesting C. coli may outcompete C. jejuni. Since a microbiota shift was observed in all inoculated groups, future Campylobacter intervention strategies may involve stabilization of the gut microbiota, making it more resilient to Campylobacter colonization in the first place.

Anti-Campylobacter Probiotics: Latest Mechanistic Insights

The Campylobacter genus is the leading cause of human gastroenteritis, with the consumption of contaminated poultry meat as the main route of infection. Probiotic bacteria, such as Lactobacillus, Bacillus, Escherichia coli Nissle, and Bifidobacterium species, have a great immunomodulatory capacity and exhibit antipathogenic effects through various molecular mechanisms. Reducing Campylobacter levels in livestock animals, such as poultry, will have a substantial benefit to humans as it will reduce disease transmissibility through the food chain. Moreover, probiotic-based strategies might attenuate intestinal inflammatory processes, which consequently reduce the severity of Campylobacter disease progression. At a molecular level, probiotics can also negatively impact on the functionality of various Campylobacter virulence and survival factors (e.g., adhesion, invasion), and on the associated colonization proteins involved in epithelial translocation. The current review describes recent in vitro, in vivo, and preclinical findings on probiotic therapies, aiming to reduce Campylobacter counts in poultry and reduce the pathogen's virulence in the avian and human host. Moreover, we focused in particular on probiotics with known anti-Campylobacter activity seeking to understand the biological mechanisms involved in their mode of action.

Investigation on the colonisation of Campylobacter strains in the pig intestine depending on available metabolites

Campylobacter (C.) spp. represent one of the most important causes for food-borne bacterial pathogen in humans worldwide. The aim of this study was to investigate metabolic requirements of two Campylobacter strains of different species based on substrate utilisation (in vitro). Based on these results, a correlation between the colonisation and the available substrates in different intestinal sections was recorded using an animal model. Campylobacter coli (ST-5777) and C. jejuni (ST-122) were used to inoculate 16 pigs, respectively, and one group of 16 pigs was used as control. The strains differed significantly in substrate utilisation - C. coli was able to metabolise various substrates (acetate, asparagine, serine, fucose, and propionate), while C. jejuni only utilised serine. Metabolomic analysis of intestinal content from different gut sections showed the presence of all previously tested metabolites, except for fucose. A significantly larger amount of glucose was found in the jejunum of those pigs infected with C. coli, while neither strain utilised it in vitro. The analysis of the intestinal contents revealed a very low proportion of Campylobacterales in the total microbiome, suggesting that the small percentage of the inoculated Campylobacter strains in the gut microflora of the animals is too low to cause differences between the control and infected groups in the composition of the metabolome. Nevertheless, knowledge of specific nutritional requirements of the pathogens combined with proof of different metabolites in the intestinal segments may provide clues about the site of colonisation in the host and improve our understanding of this zoonotic germ.

Comparative Analysis of the Gut Microbiota of Three Sympatric Terrestrial Wild Bird Species Overwintering in Farmland Habitats

The gut microbiota of wild birds are affected by complex factors, and cross-species transmission may pose challenges for the host to maintain stable gut symbionts. Farmland habitats are environments strongly manipulated by humans, and the environmental characteristics within a large area are highly consistent. These features provide the ideal natural conditions for conducting cross-species comparative studies on gut microbiota among wild birds. This study aimed to investigate and compare the gut microbiota of three common farmland-dependent bird species, Great Bustard (Otis tarda dybowskii), Common Crane (Grus grus), and Common Coot (Fulica atra), in a homogeneous habitat during the wintering period. The results indicated that under the combined action of similar influencing factors, the gut microbiota of different host species did not undergo adaptive convergence, maintained relatively independent structures, and exhibited host-driven signals. In addition, we also detected various pathogenic genera that may cause outbreaks of periodic infections among sympatric migratory birds. We conclude that phylosymbiosis may occur between some wild birds and their gut microbiota. Usage of non-invasive methods to monitor the changes in the gut microbiota of wild bird fecal samples has important implications for the conservation of endangered species.

Lactiplantibacillus plantarum Postbiotics: Alternative of Antibiotic Growth Promoter to Ameliorate Gut Health in Broiler Chickens

The postbiotic produced from Lactiplantibacillus plantarum has been revealed as a potential alternative to antibiotic growth promoters (AGP). It helps to stimulate growth performance, improve nutrient digestibility, intestinal histomorphology, immune response, and improve meat quality in livestock. However, there is a paucity of information on the effects of L. plantarum postbiotic produced by formulated media on the gut health and immune response. Therefore, this study was conducted by using three strains of dietary L. plantarum postbiotics to determine the growth performance, intestinal histomorphology, intestinal mucin production, and immune status in broiler chickens. A 245 male Cobb 500-day-old birds were assigned randomly to five treatments, namely, NC: basal diet only (negative control), OTC: basal diet + 0.01% (w/w) oxytetracycline (positive control), RG11: basal diet + 0.1% (v/w) Postbiotic RG11, RI11: basal diet + 0.1% (v/w) Postbiotic RI11, and RS5: basal diet + 0.1% (v/w) Postbiotic RS5. The body weight and feed intake were taken weekly. The small intestine and its mucus, ceca digesta were collected on days 21 and 42. Fresh excreta for crude mucin production were collected 3 days before slaughter on day 42. From the findings, RS5 recorded a significant highest (p < 0.05) final body weight, body weight gain, and significant lowest (p < 0.05) feed conversion ratio. The concentrations of glutathione peroxidase, superoxide dismutase (SOD), acidic mucin, sulfated mucin, and intestinal trefoil factor were significantly higher (p < 0.05) in the birds fed with RI11 and RS5. Postbiotics RI11 and RS5 had up-regulated expression of intestinal Mucin 2, occludin, and secretory immunoglobulin A. The antibiotic-fed chickens also showed a reduced (p < 0.05) total bacteria and Bifidobacterium population but a significantly increased (p < 0.05) the population of Escherichia coli in the jejunum. In conclusion, the supplementation of L. plantarum postbiotic can be used to substitute AGP as it promoted growth performance, mucin production, ameliorated tight junction permeability, and immune status in broiler chickens due to improved gut health and beneficial bacteria colonization.

High resolution parallel sequencing reveals multi-strain Campylobacter in broiler chicken flocks testing ‘negative’ by conventional culture methods: implications for control of Campylobacter infection

Contaminated chicken meat is a major source of human Campylobacteriosis and rates of infection remain high, despite efforts to limit the colonisation of broiler (meat) chicken flocks on farms. Using conventional testing methods of culture or qPCR, Campylobacter is typically detected amongst broiler flocks from 3 wk of age, leading to the assumption that infection is introduced horizontally into chicken rearing houses at this time. In this study, we use parallel sequencing of a fragment of the Campylobacter outer membrane protein, encoded by the porA gene, to test for presence of Campylobacter DNA amongst fresh fecal samples collected from broiler flocks aged 23 to 28 d. Campylobacter DNA was detected in all of the 290 samples tested using the porA target, and in 48% of samples using 16S bacterial profiling, irrespective of whether or not Campylobacter could be detected using conventional qPCR thresholds. A single porAf2 variant was predominant among flocks that would be determined to be Campylobacter ‘positive’ by conventional means, but a diverse pattern was seen among flocks that were Campylobacter ‘negative’. The ability to routinely detect low levels of Campylobacter amongst broiler flocks at a much earlier age than would conventionally be identified requires a re-examination of how and when biosecurity measures are best applied for live birds. In addition, it may be useful to investigate why single Campylobacter variants proliferate in some broiler flocks and not others.

Paracellular intestinal permeability of chickens induced by DON and/or C. jejuni is associated with alterations in tight junction mRNA expression

Toxins, antigens, and harmful pathogens continuously challenge the intestinal mucosa. Therefore, regulation of the intestinal barrier is crucial for the maintenance of mucosal homeostasis and gut health. Intercellular complexes, namely, tight junctions (TJs), regulate paracellular permeability. TJs are mainly composed of claudins (CLDN), occludin (OCLN), tight junction associated MARVEL-domain proteins (TAMPS), the scaffolding zonula occludens (ZO) proteins and junction-adhesion molecules (JAMs). Different studies have shown that a Campylobacter infection can lead to a phenomenon so-called "leaky gut", including the translocation of luminal bacteria to the underlying tissue and internal organs. Based on the effects of C. jejuni on the chicken gut, we hypothesize that impacts on TJ proteins play a crucial role in the destructive effects of the intestinal barrier. Likewise, the mycotoxin deoxynivalenol (DON) can also alter gut permeability in chickens. Albeit DON and C. jejuni are widely distributed, no data are available on their effect on the tight junctions' barrier in the broiler intestine and consequences for permeability. Therefore, the aim of this study was to analyze the interaction between DON and C. jejuni on the gut barrier by linking permeability with gene expression of TJ proteins and to determine the relationships between the measurements. Following oral infection of birds with C. jejuni NCTC 12744 at 14 days of age, we demonstrate that the co-exposure with DON has considerable consequences on gut permeability as well as on gut TJ mRNA expression. Co-exposure of DON and C. jejuni enhanced the negative effect on paracellular permeability of the intestine, which was also noticed for the bacteria or the mycotoxin alone by the Ussing chamber technique at certain time points in both jejunum and caecum. Furthermore, the increased paracellular permeability was associated with significant changes in TJ mRNA expression in the small and large intestine. The actual study demonstrates that co-exposure of broiler chickens to DON and C. jejuni resulted in a decreased barrier function via up-regulation of pore-forming tight junctions (CLDN7 and CLDN10), as well as the cytosolic TJ protein occludin (OCLN) that can shift to various paracellular locations and are therefore able to alter the epithelial permeability. These findings indicate that the co-exposure of broiler chickens to DON and C. jejuni affects the paracellular permeability of the gut by altering the tight junction proteins. Furthermore, analysing of correlations between TJs revealed that the mRNA expression levels of most tight junctions were correlated with each other in both jejunum and caecum. Finally, the findings indicate that the molecular composition of tight junctions can be used as a marker for gut health and integrity.

Case of necrotic enteritis associated with campylobacteriosis and coccidiosis in an adult Indian peacock (Pavo cristatus)

Background

To date, Campylobacter jejuni has not been found to be pathogenic to peafowl. The available publications show that out of a total of 44 samples tested from peafowl, this bacterium was isolated only in two cases. Eimeria pavonina infestations in the peafowl have been described, but no fatal cases have been reported yet.

Case presentation

The four-year-old peacock was presented with chronic diarrhea, emaciation and weakness. Post mortem examination revealed enlarged and pale kidneys, small intestinal mucosal necrosis and thickening of intestinal wall, and pericardial effusion. The histopathological examination revealed necrotic enteritis with marked mononuclear cells infiltration associated with the presence of coccidia, additionally there was histological evidence of septicemia in liver and kidneys. Bacteria identification was based on light microscopy of the small intestine sample, culture, and biochemical tests. Further identification was based on PCR. Antimicrobial susceptibility profile was created by determination of minimal inhibitory concentration (MIC) values for 6 antimicrobial agents from 5 different classes. PCR assays were performed to detect virulence factors genes responsible for motility, cytolethal distending toxin production, adhesion and internalization. Bacteriology of the small intestine sample showed abundant growth almost exclusively of Campylobacter jejuni, resistant to ciprofloxacin, gentamycin and ampicillin. Bacteria was sensitive to Amoxicillin + clavulanic acid, tetracycline, and erythromycin. All tested virulence factors genes have been detected. The parasitological examination was performed by microscopic examination of fresh faeces and intestinal content, and revealed the moderate number of Eimeria pavonina, Histomonas meleagridis, single Capillaria spp. eggs as well Heterakis spp. like parasites.

Conclusion

The above case shows that a virulent isolate of Campylobacter jejuni in combination with a parasitic invasion may cause chronic enteritis in peafowl, which most likely led to extreme exhaustion of the host organism and death.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03260-1.

The Role of Nutraceuticals and Phytonutrients in Chickens’ Gastrointestinal Diseases

Simple Summary

The use of nutraceuticals and phytonutrients in poultry nutrition has been extensively explored over the past decade. The interest in these substances is linked to the search for natural compounds that can be effectively used to prevent and treat some of the main diseases of the chicken. The serious problem of antibiotic resistance and the consequent legislative constraints on their use required the search for alternatives. The purpose of this review is to describe the current status of the effects of some substances, such as probiotics and prebiotics, organic acids, vitamins and phytogenic feed additives, focusing specifically on studies concerning the prevention and treatment of four main gastrointestinal diseases in chicken: salmonellosis, necrotic enteritis (caused by Clostridium perfringens), campylobacteriosis, and coccidiosis. A brief description of these diseases and the effects of the main bioactive principles of the nutraceutical or phytonutrient groups will be provided. Although there are conflicting results, some works show very promising effects, with a reduction in the bacterial or protozoan load following treatment. Further studies are needed to verify the real effectiveness of these compounds and make them applicable in the field.

Abstract

In poultry, severe gastrointestinal diseases are caused by bacteria and coccidia, with important economic losses in the poultry industry and requirement of treatments which, for years, were based on the use of antibiotics and chemotherapies. Furthermore, Salmonella spp., Clostridium perfringens, and Campylobacter jejuni can cause serious foodborne diseases in people, resulting from consumption of poultry meat, eggs, and derived products. With the spread of antibiotic resistance, which affects both animals and humans, the restriction of antibiotic use in livestock production and the identification of a list of “critically important antimicrobials” became necessary. For this reason, researchers focused on natural compounds and effective alternatives to prevent gastrointestinal disease in poultry. This review summarizes the results of several studies published in the last decade, describing the use of different nutraceutical or phytonutrients in poultry industry. The results of the use of these products are not always encouraging. While some of the alternatives have proven to be very promising, further studies will be needed to verify the efficacy and practical applicability of other compounds.

The cost of bacterial predation via type VI secretion system leads to predator extinction under environmental stress

As a common gut pathogen, Campylobacter jejuni (C. jejuni) harbors the Type VI Secretion System (T6SS) that injects toxic effectors into neighboring cells, modulating microbial competitions in the harsh gut environment. Using bile salt as a natural stressor and T6SS-positive C. jejuni as a predator, we show that T6SS activity could entail a cost during bacterial predation under environmental stress. Our data suggest bile salt influx and subsequent DNA damage due to the prey-driven activation of the T6SS. We further combined experiments and mathematical modeling to explore how the stress-induced “predation cost” determines ecological outcomes. Consistent with a population-dynamics model, we found predator extinction above a critical bile salt concentration and prey-predator coexistence below this level. Moreover, we utilized the predation cost as an effective strategy facilitating host defense against C. jejuni infection. Together, we elucidate how predator dominance versus extinction emerges from the interplay between environmental stress and the T6SS machinery.

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Campylobacter jejuni uses Type VI secretion system (T6SS) to kill prey bacteria

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Under bile salt stress, activated T6SS may promote bile salt uptake and DNA damage

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T6SS-dependent predation by C. jejuni thus entails a “predation cost” under stress

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The predation cost leads to predator extinction and host defense against C. jejuni

Lactic Acid Bacteria - A Promising Tool for Controlling Chicken Campylobacter Infection

Since 2005, campylobacteriosis has been the most common zoonotic disease in Europe. The main reservoir of pathogenic Campylobacter strains is broilers, which makes raw and undercooked poultry meat two major sources of disease. Infection in chicken flocks is most often asymptomatic, despite a high level of colonization reaching 106-109cfu/g in animal ceca. It is widely believed that controlling the level of colonization of the birds' digestive tract by pathogenic strains is a good way to increase food safety. Many treatments have been proposed to combat or at least reduce the level of colonization in animals reservoirs: probiotics, bacteriophages, vaccines, and anti-Campylobacter bacteriocins. This review focuses on the effects of Campylobacter infection on the chicken microbiome and colonization control strategies using probiotics (mostly lactic acid bacteria, LAB), which are live microorganisms included in the diet of animals as feed additives or supplements. Probiotics are not only an alternative to antibiotics, which were used for years as animal growth promoters, but they also constitute an effective protective barrier against excessive colonization of the digestive system by pathogenic bacteria, including Campylobacter. Moreover, one of the many beneficial functions of probiotics is the ability to manipulate the host's microbiota. Recently, there have also been some promising attempts to use lactic acid bacteria as a delivery system of oral vaccine against Campylobacter. Recombinant LAB strains induce primarily a mucosal immune response against foreign antigens, accompanied by at most a low-level immune response against carrier strains. Since the main barrier against the invasion of pathogens in the gastrointestinal tract is the intestinal mucosal membrane, the development of effective oral vaccines to protect animals against enteric infection is very reasonable.

Folic Acid Absorption Characteristics and Effect on Cecal Microbiota of Laying Hens

This experiment was conducted to investigate the characteristics of folic acid (FA) absorption in laying hens and the effect of FA supplementation on cecal microbiota. A total of 432 healthy hens (30-week-old) were randomly assigned to four diets supplemented with FA: 0, 1, 6, and 24 mg/kg of feed for 8 w. Blood, duodenum, jejunum, ileum, cecum, and cecal chyme samples (six samples per treatment) were collected from the hens at the end of the feeding trial. Expression profiles of folate transport and transformation genes in intestine and cecal microbiota were detected. Results showed that serum folate level significantly increased (P < 0.01) with an increase in dietary FA supplementation, reaching a plateau at 6 mg/kg FA supplementation. The expression of FA transport and transformation genes was not affected in the cecum (P > 0.05) by dietary FA supplementation; however, it was affected in the duodenum, jejunum, and ileum and mostly showed a downward trend in treatment groups (P < 0.05). The genes affected include duodenal folate receptor (Folr) and dihydrofolate reductase (Dhfr), jejunal proton-coupled folate transporter (Pcft) and reduced folate carrier (Rfc), and ileal ATP binding cassette subfamily C member (Abcc2), Abcc3, Rfc, Folr, and Dhfr. Furthermore, according to the operational taxonomic unit classification and taxonomic position identification, the cecal microbiota population of the hens was not affected by dietary FA supplementation at the phylum, class, order, family, genus, and species levels (P > 0.05). However, the relative abundance of some microbiota was affected by dietary FA supplementation (P < 0.05). In conclusion, FA transport from the intestinal lumen into enterocytes, and then into the bloodstream, is strictly regulated, which may be associated with the regulation of the expression profiles of genes involved in FA absorption. Pathogenic bacteria decreased in the cecum, especially at 24 mg/kg supplementation, but the beneficial bacteria (Bifidobacteriaceae) decreased at this level, too. Overall, FA supplementation at 6 mg/kg, which was selected for folate-enriched egg production, did not affect the health and metabolism of laying hens negatively.

Deepoxy-deoxynivalenol (DOM-1), a derivate of deoxynivalenol (DON), exhibits less toxicity on intestinal barrier function, Campylobacter jejuni colonization and translocation in broiler chickens

Background

Intestinal epithelial cells are challenged by mycotoxins and many bacterial pathogens. It was previously shown that the mycotoxin deoxynivalenol (DON) as well as Campylobacter (C.) jejuni have a negative impact on gut integrity. Recently, it was demonstrated that DON increased the load of C. jejuni in the gut and inner organs. Based on this finding, it was hypothesized the DON metabolite (deepoxy-deoxynivalenol, DOM-1) should be able to reduce the negative effects of DON on colonization and translocation of C. jejuni in broilers, since it lacks the epoxide ring, which is responsible for the toxicity of DON.

Methods

A total of 180 broiler chickens were housed in floor pens on wood shavings with feed and water provided ad libitum. Birds were divided into six groups (n = 30 with 5 replicates/group): 1. Control, 2. DOM-1, 3. DON, 4. DOM-1 + C. jejuni, 5. DON + C. jejuni, 6. C. jejuni. At day 14, birds of groups 4, 5 and 6 were orally inoculated via feeding tube (gavage) with 1-ml of a PBS suspension containing 1 × 10⁸ CFU of C. jejuni NCTC 12744. The performance parameters: body weight (BW), body weight gain (BWG), and feed intake of the birds were determined. At 7, 14, and 21 days post infection, samples from liver, spleen, duodenum, jejunum and cecum were aseptically collected and processed for bacteriological investigations. Finally, at each killing time point, segments of duodenum, jejunum and cecum were harvested and prepared for Ussing chamber studies to measure the paracellular mannitol fluxes.

Results

A significant decrease in body weight was observed for chickens receiving the DON diet with or without C. jejuni compared to the other groups. Furthermore, it was found that the co-exposure of birds to DON and C. jejuni resulted in a higher C. jejuni load not only in the gut but also in liver and spleen due to increased paracellular permeability of the duodenum, jejunum and cecum. On the contrary, DOM-1 supplementation in the feed improved the birds’ performance and led to a better feed conversion ratio throughout the trial. Furthermore, DOM-1 did not negatively affect gut permeability and decreased the C. jejuni counts in the intestine and internal organs.

Conclusion

Altogether, the presence of DOM-1 in the feed as a result of the enzymatic biotransformation of DON leads to a lower C. jejuni count in the intestine and better feed conversion ratio. Moreover, this study demonstrates that the detoxification product of DON, DOM-1, does not have negative effects on the gastrointestinal tract and reduces the Campylobacter burden in chickens and also the risk for human infection.

Passive Immunization of Chickens with Anti-Enterobactin Egg Yolk Powder for Campylobacter Control

Enterobactin (Ent) is a highly conserved and important siderophore for the growth of many Gram-negative bacterial pathogens. Therefore, targeting Ent for developing innovative intervention strategies has attracted substantial research interest in recent years. Recently, we developed a novel Ent conjugate vaccine that has been demonstrated to be effective for controlling Gram-negative pathogens using both in vitro and in vivosystems. In particular, active immunization of chickens with the Ent conjugate vaccine elicited strong immune responses and significantly reduced intestinal colonization of Campylobacter jejuni, the leading foodborne bacterial pathogen. Given that hyperimmune egg yolk immunoglobulin Y (IgY) has been increasingly recognized as a promising and practical non-antibiotic approach for passive immune protection against pathogens in livestock, in this study, we assessed the efficacy of oral administration of broiler chickens with the anti-Ent hyperimmune egg yolk powder to control C. jejuni colonization in the intestine. However, supplementation of feed with 2% (w/w) of anti-Ent egg yolk powder failed to reduce C. jejuni colonization when compared to the control group. Consistent with this finding, the ELISA titers of the specific IgY in cecum, ileum, duodenum, gizzard, and serum contents were similar between the two groups throughout the trial. Chicken intestinal microbiota also did not change in response to the egg yolk powder treatment. Subsequently, to examine ex vivo stability of the egg yolk IgY, the chicken gizzard and duodenum contents from two independent sources were spiked with the egg yolk antibodies, incubated at 42 °C for different lengths of time, and subjected to ELISA analysis. The specific IgY titers were dramatically decreased in gizzard contents (up to 2048-fold) but were not changed in duodenum contents. Collectively, oral administration of broiler chickens with the anti-Ent egg yolk powder failed to confer protection against intestinal colonization of C. jejuni, which was due to instability of the IgY in gizzard contents as demonstrated by both in vivo and ex vivo evidence.

Identifying the targets and functions of N-linked protein glycosylation in Campylobacter jejuni

Campylobacter jejuni is a major cause of bacterial gastroenteritis in humans that is primarily associated with the consumption of inadequately prepared poultry products, since the organism is generally thought to be asymptomatic in avian species. Unlike many other microorganisms, C. jejuni is capable of performing extensive post-translational modification (PTM) of proteins by N- and O-linked glycosylation, both of which are required for optimal chicken colonization and human virulence. The biosynthesis and attachment of N-glycans to C. jejuni proteins is encoded by the pgl (protein glycosylation) locus, with the PglB oligosaccharyltransferase (OST) enabling en bloc transfer of a heptasaccharide N-glycan from a lipid carrier in the inner membrane to proteins exposed within the periplasm. Seventy-eight C. jejuni glycoproteins (represented by 134 sites of experimentally verified N-glycosylation) have now been identified, and include inner and outer membrane proteins, periplasmic proteins and lipoproteins, which are generally of poorly defined or unknown function. Despite our extensive knowledge of the targets of this apparently widespread process, we still do not fully understand the role N-glycosylation plays biologically, although several phenotypes, including wild-type stress resistance, biofilm formation, motility and chemotaxis have been related to a functional pgl system. Recent work has described enzymatic processes (nitrate reductase NapAB) and antibiotic efflux (CmeABC) as major targets requiring N-glycan attachment for optimal function, and experimental evidence also points to roles in cell binding via glycan-glycan interactions, protein complex formation and protein stability by conferring protection against host and bacterial proteolytic activity. Here we examine the biochemistry of the N-linked glycosylation system, define its currently known protein targets and discuss evidence for the structural and functional roles of this PTM in individual proteins and globally in C. jejuni pathogenesis.

Association of Broiler Litter Microbiome Composition and Campylobacter Isolation

Infection with Campylobacter species is one of the leading causes of bacterial diarrhea in humans in the US. Chickens, which become colonized on the farm, are important reservoirs of this bacterium. Campylobacter can establish itself in the broiler house via a variety of sources, can survive in the litter of the house, and possibly persist over successive flock cycles. However, the role of the broiler litter microbiome on Campylobacter persistence is not clear. A matched case-control study was conducted to determine whether the broiler litter microbiome composition was associated with Campylobacter isolation within the broiler house. Flocks were classified as cases when either Campylobacter jejuni or Campylobacter coli was isolated in boot sock samples, or as controls otherwise. Case and control flocks were matched at the broiler house level. Composite broiler litter samples were collected and used for DNA extraction and 16S rRNA gene V4 region sequencing. Reads were processed using the DADA2 pipeline to obtain a table of amplicon sequence variants. Alpha diversity and differential bacterial relative abundance were used as predictors of Campylobacter isolation status in conditional logistic regression models adjusting for flock age and sampling season. Beta diversity distances were used as regressors in stratified PERMANOVA with Campylobacter isolation status as predictor, and broiler house as stratum. When Campylobacter was isolated in boot socks, broiler litter microbiome richness and evenness were lower and higher, respectively, without reaching statistical significance. Campylobacter isolation status significantly explained a small proportion of the beta diversity (genus-level Aitchison dissimilarity distance). Clostridium and Anaerostipes were positively associated with Campylobacter isolation status, whereas Bifidobacterium, Anaerosporobacter, and Stenotrophomonas were negatively associated. Our results suggest the presence of bacterial interactions between Campylobacter and the broiler litter microbiome. The negative association of Campylobacter with Bifidobacterium, Anaerosporobacter, and Stenotrophomonas in litter could be potentially exploited as a pre-harvest control strategy.

The Use of Probiotics in the Reduction of Campylobacter spp. Prevalence in Poultry

Campylobacter spp. are widely distributed microorganisms, many of which are commensals of gastrointestinal tract in multiple animal species, including poultry. Most commonly detected are C. jejuni and C. coli. Although infections are usually asymptomatic in poultry, poultry meat and products represent main sources of infection with these bacteria to humans. According to recent EFSA report, campylobacteriosis is the most commonly reported zoonotic disease. In 2018, EFSA Panel on Biological Hazards indicated that use of feed and water additives is the second most likely strategy that can be successful in minimizing Campylobacter spp. colonization rate in broiler chickens. One of those feed and water additives are probiotics. From numerous research papers it can be concluded that probiotics exhibit plenty of mechanisms of anti-Campylobacter activity, which were evaluated under in vitro conditions. These results, to some extent, can explain the efficacy of probiotics in in vivo studies, although different outcome can be observed under these two laboratory conditions. Probiotics are capable of reducing Campylobacter spp. population count in poultry gastrointestinal tract and they can reduce carcass contamination. Potential modes of anti-Campylobacter activity of probiotics, results of in vivo studies and studies performed at a farm level are widely discussed in the paper.

The Acute Host-Response of Turkeys Colonized With Campylobacter coli

Consumption of contaminated poultry products is one of the main sources of human campylobacteriosis, of which Campylobacter jejuni subsp. jejuni (C. jejuni) and C. coli are responsible for ~98% of the cases. In turkeys, the ceca are an important anatomical site where Campylobacter asymptomatically colonizes. We previously demonstrated that commercial turkey poults colonized by C. jejuni showed acute changes in cytokine gene expression profiles, and histological intestinal lesions at 2 days post-inoculation (dpi). Cecal tonsils (CT) are an important part of the gastrointestinal-associated lymphoid tissue that surveil material passing in and out of the ceca, and generate immune responses against intestinal pathogens. The CT immune response toward Campylobacter remains unknown. In this study, we generated a kanamycin-resistant C. coli construct (CcK) to facilitate its enumeration from cecal contents after experimental challenge. In vitro analysis of CcK demonstrated no changes in motility when compared to the parent isolate. Poults were inoculated by oral gavage with CcK (5 × 107 colony forming units) or sterile-media (mock-colonized), and euthanized at 1 and 3 dpi. At both time points, CcK was recovered from cecal contents, but not from the mock-colonized group. As a marker of acute inflammation, serum alpha-1 acid glycoprotein was significantly elevated at 3 dpi in CcK inoculated poults compared to mock-infected samples. Significant histological lesions were detected in cecal and CT tissues of CcK colonized poults at 1 and 3 dpi, respectively. RNAseq analysis identified 250 differentially expressed genes (DEG) in CT from CcK colonized poults at 3 dpi, of which 194 were upregulated and 56 were downregulated. From the DEG, 9 significantly enriched biological pathways were identified, including platelet aggregation, response to oxidative stress and negative regulation of oxidative stress-induced intrinsic apoptotic signaling pathway. These data suggest that C. coli induced an acute inflammatory response in the intestinal tract of poults, and that platelet aggregation and oxidative stress in the CT may affect the turkey's ability to resist Campylobacter colonization. These findings will help to develop and test Campylobacter mitigation strategies to promote food safety in commercial turkeys.

The Interplay between Campylobacter and the Caecal Microbial Community of Commercial Broiler Chickens over Time

Campylobacter is the most frequent foodborne zoonotic bacteria worldwide, with chicken meat being overwhelmingly the most important reservoir for human infections. Control measures implemented at the farm level (i.e., biosecurity or vaccination), which have been successfully applied to limit other pathogens, such as Salmonella, have not been effective in reducing Campylobacter occurrence. Thus, new approaches are needed to fully understand the ecological interactions of Campylobacter with host animals to effectively comprehend its epidemiology. The objective of this study was to analyse longitudinally the gut microbiota composition of Campylobacter-infected and non-infected farms to identify any difference that could potentially be indicative of gut colonization by Campylobacter spp. Differences in the colonization rate and timing were observed at the farms that became positive for Campylobacter jejuni over the investigated time points, even though in positive tests, the occurrence of Campylobacter jejuni gut colonization was not observed before the second week of the life of the birds. Significant differences were observed in the abundances of specific bacterial taxa between the microbiota of individuals belonging to farms that became Campylobacter positive during the study and those who remained negative with particular reference to Bacteroidales and Clostridiales, respectively. Moreover, Campylobacter colonization dramatically influenced the microbiota richness, although to a different extent depending on the infection timing. Finally, a key role of Faecalibacterium and Lactobacillus genera on the Campylobacter microbial network was observed. Understanding the ecology of the Campylobacter interaction with host microbiota during infection could support novel approaches for broiler microbial barrier restoration. Therefore, evidence obtained through this study can be used to identify options to reduce the incidence of infection at a primary production level based on the targeted influence of the intestinal microbiota, thus helping develop new control strategies in order to mitigate the risk of human exposure to Campylobacter by chicken meat consumption.

Current Perspectives and Potential of Probiotics to Limit Foodborne Campylobacter in Poultry

Poultry has been one of the major contributors of Campylobacter related human foodborne illness. Numerous interventions have been applied to limit Campylobacter colonization in poultry at the farm level, but other strategies are under investigation to achieve more efficient control. Probiotics are viable microbial cultures that can establish in the gastrointestinal tract (GIT) of the host animal and elicit health and nutrition benefits. In addition, the early establishment of probiotics in the GIT can serve as a barrier to foodborne pathogen colonization. Thus, probiotics are a potential feed additive for reducing and eliminating the colonization of Campylobacter in the GIT of poultry. Screening probiotic candidates is laborious and time-consuming, requiring several tests and validations both in vitro and in vivo. The selected probiotic candidate should possess the desired physiological characteristics and anti-Campylobacter effects. Probiotics that limit Campylobacter colonization in the GIT rely on different mechanistic strategies such as competitive exclusion, antagonism, and immunomodulation. Although numerous research efforts have been made, the application of Campylobacter limiting probiotics used in poultry remains somewhat elusive. This review summarizes current research progress on identifying and developing probiotics against Campylobacter and presenting possible directions for future research efforts.

The Mycotoxin Deoxynivalenol (DON) Promotes Campylobacter jejuni Multiplication in the Intestine of Broiler Chickens With Consequences on Bacterial Translocation and Gut Integrity

Deoxynivalenol (DON) is one of the major health concern in poultry production as it targets epithelial cells of the gastrointestinal tract and contributes to the loss of the epithelial barrier function. It is well-documented that DON severely compromises various important intestinal functions in coincidence with aggravated clinical symptoms in livestock. In addition, a prolonged persistence of intestinal pathogens (e.g., Salmonella, Clostridium) in the gut has also been reported in pigs and chickens, respectively. Similar to DON, recent studies demonstrated that an experimental Campylobacter infection has severe consequences on gut health. Through experimental infection, it was found that Campylobacter (C.) jejuni negatively affects the integrity of the intestine and promotes the translocation of bacteria from the gut to inner organs. So far, no data are available investigating the simultaneous exposure of DON and C. jejuni in broilers albeit both are widely distributed. Thus, the aim of the present study was to explore the interaction between DON and C. jejuni which is of a significant public and animal health concern as it may affect the prevalence and the ability to control this pathogen. Following oral infection of birds at 14 days of age with C. jejuni NCTC 12744, we show that the co-exposure to DON and C. jejuni has a considerable consequence on C. jejuni loads in chicken gut as well as on gut permeability of the birds. A reduced growth performance was found for DON and/or C. jejuni exposed birds. Furthermore, it was found that the co-exposure of DON and C. jejuni aggravated the negative effect on paracellular permeability of the intestine already noticed for the bacteria or the mycotoxin alone by the Ussing chamber technique at certain times or intestinal segments. Furthermore, the increased paracellular permeability promotes the translocation of C. jejuni and E. coli to inner organs, namely liver and spleen. Interestingly, C. jejuni loads in the intestine were higher in DON-fed groups indicating a supportive growth effect of the mycotoxin. The actual study demonstrates that co-exposure of broiler chickens to DON and C. jejuni has not only considerable consequences on gut integrity but also on bacterial balance. These findings indicate that the co-exposure of broiler chickens to DON and C. jejuni could have a significant impact on gut health and bacteria translocation leading to an increased risk for public health.

Campylobacter sp.: Pathogenicity factors and prevention methods-new molecular targets for innovative antivirulence drugs?

Infections caused by bacterial species from the genus Campylobacter are one of the four main causes of strong diarrheal enteritis worldwide. Campylobacteriosis, a typical food-borne disease, can range from mild symptoms to fatal illness. About 550 million people worldwide suffer from campylobacteriosis and lethality is about 33 million p.a. This review summarizes the state of the current knowledge on Campylobacter with focus on its specific virulence factors. Using this knowledge, multifactorial prevention strategies can be implemented to reduce the prevalence of Campylobacter in the food chain. In particular, antiadhesive strategies with specific adhesion inhibitors seem to be a promising concept for reducing Campylobacter bacterial load in poultry production. Antivirulence compounds against bacterial adhesion to and/or invasion into the host cells can open new fields for innovative antibacterial agents. Influencing chemotaxis, biofilm formation, quorum sensing, secretion systems, or toxins by specific inhibitors can help to reduce virulence of the bacterium. In addition, the unusual glycosylation of the bacterium, being a prerequisite for effective phase variation and adaption to different hosts, is yet an unexplored target for combating Campylobacter sp. Plant extracts are widely used remedies in developing countries to combat infections with Campylobacter. Therefore, the present review summarizes the use of natural products against the bacterium in an attempt to stimulate innovative research concepts on the manifold still open questions behind Campylobacter towards improved treatment and sanitation of animal vectors, treatment of infected patients, and new strategies for prevention. KEY POINTS: • Campylobacter sp. is a main cause of strong enteritis worldwide. • Main virulence factors: cytolethal distending toxin, adhesion proteins, invasion machinery. • Strong need for development of antivirulence compounds.

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.

Campylobacter jejuni increases the paracellular permeability of broiler chickens in a dose-dependent manner

In recent years, several studies emphasize the deleterious effects of Campylobacter jejuni on the chicken intestine. In this context, it was shown that C. jejuni, contrary to the general belief, has a negative influence on the gut barrier in chickens. More precisely, we demonstrated that C. jejuni affects gut physiology characterized by changes in ion transport and transepithelial ion conductance, but the underlying mechanism is yet to be investigated. In the actual study, to determine epithelial paracellular permeability, the mucosal to serosal flux of 14C-mannitol in the small and large intestine was measured applying Ussing chamber. A total of seventy-five 1-day-old Ross 308 broiler chickens were housed in floor pens on wood shavings with feed and water provided ad libitum. Birds were randomly allocated to 3 different groups (n = 25 with 5 replicates/group) and infected at 14 d of age with a high (108 colony forming units [CFU]) or a low (104 CFU) dose of C. jejuni and a third group kept as noninfected control. Infection with the low dose of C. jejuni resulted in delayed cecal colonization but equalized at 21 d postinfection, independent of the dose. Invasion of liver and spleen with C. jejuni was only noticed in birds infected with 108 (CFU). Body weight (BW) and body weight gain of all birds infected with C. jejuni were lower than in the control group and varied with the dose of infection, confirming a negative correlation between the infection dose and birds BW. Mannitol flux in jejunum and cecum was significantly (P < 0.05) higher in all C. jejuni infected birds compared with control birds. Likewise, significant differences in mannitol flux of both jejunum and cecum were detected depending on the infection dose of C. jejuni. The correlation analyses revealed a positive relationship between Campylobacter dose and mannitol flux of both jejunum and cecum. Altogether, the actual results emphasize that the adverse effect of C. jejuni on gut permeability arises in a dose-dependent manner.

An in vitro investigation of the survival and/or growth of Campylobacter jejuni in broiler digestate from different feed types

Campylobacter spp. is the leading cause of bacterial gastroenteritis worldwide and poultry are the primary reservoir. The aim of this study was to investigate the survival and/or growth of Campylobacter jejuni NCTC 11168 in broiler digestate prepared from commercial starter, grower and finisher feed formulations. Bolton broth and digestates were prepared, inoculated with C. jejuni NCTC 11168 (approximately 3 log₁₀ CFU per ml) and incubated under microaerobic conditions at 42°C for 24 h. Samples were taken at t = 0 (immediately after inoculation) and every 3 h thereafter, serially diluted and plated onto mCCDA. Campylobacter jejuni grew as expected in Bolton broth (control) reaching the early stationary phase after approximately 15 h. In contrast, although bacterial concentrations were maintained for at least 9 h, none of the feed digestates supported the growth of C. jejuni, which were not detected after 15 h. It is suggested that the nutrients available in the feed digestates are not enough to support C. jejuni growth and that additional factors may be at play in the avian gastrointestinal tract.

Effects of Lactobacillus Fermentum Supplementation on Body Weight and Pro-Inflammatory Cytokine Expression in Campylobacter Jejuni-Challenged Chickens

Due to the interest in using probiotic bacteria in poultry production, this research was focused on evaluating the effects of Lactobacillus fermentum Biocenol CCM 7514 administration on body weight gain and cytokine gene expression in chickens challenged with Campylobacter jejuni. One-hundred and eight 1-day old COBB 500 broiler chickens were equally assigned to four experimental groups at random. In the control group (C) chicks were left untreated, whereas in groups LB and LBCj a suspension of L. fermentum was administered. A suspension of C. jejuni was subsequently applied to groups Cj and LBCj. Body weight was registered, and the individuals were later slaughtered; cecum samples were collected at 12, 36 and 48 h post-infection (hpi). The entire experiment lasted seven days. Reverse transcription quantitative PCR (RT-qPCR) was used to determine expression levels of IL-1β, IL-15, IL-17, and IL-18 at each time point. Pathogen-infected individuals were observed to weigh significantly less than those fed with the probiotic. Significant differences were also found in transcript abundance; expression of IL-15 was downregulated by the probiotic and upregulated by C. jejuni. The effects of bacterial treatments were time-dependent, as the expression profiles differed at later stages. The present outcomes demonstrate that L. fermentum both reduces the impact of C. jejuni infection on chicken body weight and regulates positively pro-inflammatory cytokine expression, which ultimately increase bird well-being and improves production.