The role of probiotics in the inhibition of Campylobacter jejuni colonization and virulence attenuation

Mechanistic concepts involved in biofilm associated processes of Campylobacter jejuni: persistence and inhibition in poultry environments

Campylobacter species, predominantly Campylobacter jejuni, remains a significant zoonotic pathogen worldwide, with the poultry sector being the primary vector for human transmission. In recent years. there has been a notable rise in the incidence of human campylobacteriosis, necessitating a deeper understanding of the pathogen's survival mechanisms and transmission dynamics. Biofilm presence significantly contributes to C. jejuni persistence in poultry and subsequent food product contamination, and this review describes the intricate processes involved in biofilm formation. The ability of Campylobacter to form biofilms on various surfaces, including stainless steel, plastic, and glass, is a critical survival strategy. Campylobacter biofilms, with their remarkable resilience, protect the pathogen from environmental stresses such as desiccation, pH extremes, biocides and sanitizing agents. This review explores the molecular and genetic mechanisms of C. jejuni biofilm formation, highlighting regulatory genes involved in motility, chemotaxis, and stress responses. Flagellar proteins, particularly flaA, flaB, flaG, and adhesins like cadF and flpA, are identified as the main molecular components in biofilm development. The role of mixed-species biofilms, where C. jejuni integrates into existing biofilms of other bacteria to enhance pathogen resilience, is also discussed. This review also considers alternative interventions to control C. jejuni in poultry production, in the context of increasing antibiotic resistance. It explores the effectiveness of prebiotics, probiotics, synbiotics, bacteriocins, bacteriophages, vaccines, and organic acids, with a focus on their mechanisms of action in reducing bacterial colonization and biofilm formation. Studies show that mixtures of organic acids and compounds like Carvacrol and Eugenol significantly downregulate genes linked with motility and adhesion, thereby disrupting biofilm integrity. It discusses the impact of environmental factors, such as temperature and oxygen levels on biofilm formation, providing insights into how industrial conditions can be manipulated to reduce contamination. This paper stresses the need for a multifaceted approach to control Campylobacter in poultry, integrating molecular and genetic insights with practical interventions. By advancing our understanding of biofilm dynamics and gene regulation, we aim to inform the development of more effective strategies to enhance food safety and protect public health.

Oral administration of Limosilactobacillus ingluviei C37 inhibits Campylobacter jejuni colonization in chicks

As the global population continues to grow, so too does the demand for poultry meat. However, the concurrent increase in the prevalence of drug-resistant bacteria has stimulated interest in the search for alternatives to antibiotics in poultry and livestock agriculture. One potential strategy is the use of probiotics. In this study, we showed that prophylactic oral administration of Limosilactobacillus ingluviei C37 (LIC37) reduced Campylobacter jejuni colonization of the cecum in cage-raised chicks, without causing significant changes in the overall diversity of gut bacteria. Further, the abundance of Blautia, another genus of probiotic bacteria, increased in the gastrointestinal tract following ingestion of LIC37 by chicks. These findings suggest that LIC37 could potentially be used as a novel probiotic agent against C. jejuni in livestock production.

Genomic tailoring of autogenous poultry vaccines to reduce Campylobacter from farm to fork

Campylobacter is a leading cause of food-borne gastroenteritis worldwide, linked to the consumption of contaminated poultry meat. Targeting this pathogen at source, vaccines for poultry can provide short-term caecal reductions in Campylobacter numbers in the chicken intestine. However, this approach is unlikely to reduce Campylobacter in the food chain or human incidence. This is likely as vaccines typically target only a subset of the high genomic strain diversity circulating among chicken flocks, and rapid evolution diminishes vaccine efficacy over time. To address this, we used a genomic approach to develop a whole-cell autogenous vaccine targeting isolates harbouring genes linked to survival outside of the host. We hyper-immunised a whole major UK breeder farm to passively target offspring colonisation using maternally-derived antibody. Monitoring progeny, broiler flocks revealed a near-complete shift in the post-vaccination Campylobacter population with an ~50% reduction in isolates harbouring extra-intestinal survival genes and a significant reduction of Campylobacter cells surviving on the surface of meat. Based on these findings, we developed a logistic regression model that predicted that vaccine efficacy could be extended to target 65% of a population of clinically relevant strains. Immuno-manipulation of poultry microbiomes towards less harmful commensal isolates by competitive exclusion, has major potential for reducing pathogens in the food production chain.

Survival Time of Campylobacter jejuni in Broiler Crops

Lactobacillus spp. inhibit the growth of Campylobacter spp. in vitro. However, in chicken crops, in which Lactobacillus spp. predominate, such inhibition of Campylobacter has not been confirmed. In our previous study, feeding paddy rice to broiler chicks increased the residence time of the food, which might enhance the bactericidal activity of the crop. Here, the bactericidal activity against the remaining Campylobacter spp. in broiler crops was evaluated. A suspension prepared by mixing Campylobacter jejuni and titanium dioxide (TiO2) was inoculated into the pharynx of 26-day-old broiler chicks fed a paddy rice-based diet. The crop contents were sampled at 20-min intervals. The TiO2 residual ratio in the crop gradually decreased with time after inoculation, with 57% of the inoculated TiO2 remaining in the crop 60 min after inoculation. The survival fraction of C. jejuni in the crops was 11% at 40 min, only 1% at 60 min, and was undetectable at 80 min. Most of the inoculated C. jejuni died in the crop before entering the next segment. These data indicated that bacterial death occurred between 30 min and 40 min after inoculation. The average survival time of C. jejuni in the crop was calculated to be 37.1 min. Thus, C. jejuni remaining in a chicken crop for more than 40 min died.

Antimicrobial Drug Resistance in Poultry Production: Current Status and Innovative Strategies for Bacterial Control

The world population’s significant increase has promoted a higher consumption of poultry products, which must meet the specified demand while maintaining their quality and safety. It is well known that conventional antimicrobials (antibiotics) have been used in livestock production, including poultry, as a preventive measure against or for the treatment of infectious bacterial diseases. Unfortunately, the use and misuse of these compounds has led to the development and dissemination of antimicrobial drug resistance, which is currently a serious public health concern. Multidrug-resistant bacteria are on the rise, being responsible for serious infections in humans and animals; hence, the goal of this review is to discuss the consequences of antimicrobial drug resistance in poultry production, focusing on the current status of this agroeconomic sector. Novel bacterial control strategies under investigation for application in this industry are also described. These innovative approaches include antimicrobial peptides, bacteriophages, probiotics and nanoparticles. Challenges related to the application of these methods are also discussed.

Campylobacter jejuni: targeting host cells, adhesion, invasion, and survival

Campylobacter jejuni, causing strong enteritis, is an unusual bacterium with numerous peculiarities. Chemotactically controlled motility in viscous milieu allows targeted navigation to intestinal mucus and colonization. By phase variation, quorum sensing, extensive O-and N-glycosylation and use of the flagellum as type-3-secretion system C. jejuni adapts effectively to environmental conditions. C. jejuni utilizes proteases to open cell-cell junctions and subsequently transmigrates paracellularly. Fibronectin at the basolateral side of polarized epithelial cells serves as binding site for adhesins CadF and FlpA, leading to intracellular signaling, which again triggers membrane ruffling and reduced host cell migration by focal adhesion. Cell contacts of C. jejuni results in its secretion of invasion antigens, which induce membrane ruffling by paxillin-independent pathway. In addition to fibronectin-binding proteins, other adhesins with other target structures and lectins and their corresponding sugar structures are involved in host-pathogen interaction. Invasion into the intestinal epithelial cell depends on host cell structures. Fibronectin, clathrin, and dynein influence cytoskeletal restructuring, endocytosis, and vesicular transport, through different mechanisms. C. jejuni can persist over a 72-h period in the cell. Campylobacter-containing vacuoles, avoid fusion with lysosomes and enter the perinuclear space via dynein, inducing signaling pathways. Secretion of cytolethal distending toxin directs the cell into programmed cell death, including the pyroptotic release of proinflammatory substances from the destroyed cell compartments. The immune system reacts with an inflammatory cascade by participation of numerous immune cells. The development of autoantibodies, directed not only against lipooligosaccharides, but also against endogenous gangliosides, triggers autoimmune diseases. Lesions of the epithelium result in loss of electrolytes, water, and blood, leading to diarrhea, which flushes out mucus containing C. jejuni. Together with the response of the immune system, this limits infection time. Based on the structural interactions between host cell and bacterium, the numerous virulence mechanisms, signaling, and effects that characterize the infection process of C. jejuni, a wide variety of targets for attenuation of the pathogen can be characterized. The review summarizes strategies of C. jejuni for host-pathogen interaction and should stimulate innovative research towards improved definition of targets for future drug development. KEY POINTS: • Bacterial adhesion of Campylobacter to host cells and invasion into host cells are strictly coordinated processes, which can serve as targets to prevent infection. • Reaction and signalling of host cell depend on the cell type. • Campylobacter virulence factors can be used as targets for development of antivirulence drug compounds.

Campylobacter jejuni in Poultry: Pathogenesis and Control Strategies

C. jejuni is the leading cause of human foodborne illness associated with poultry, beef, and pork consumption. C. jejuni is highly prevalent in commercial poultry farms, where horizontal transmission from the environment is considered to be the primary source of C. jejuni. As an enteric pathogen, C. jejuni expresses virulence factors regulated by a two-component system that mediates C. jejuni's ability to survive in the host. C. jejuni survives and reproduces in the avian intestinal mucus. The avian intestinal mucus is highly sulfated and sialylated compared with the human mucus modulating C. jejuni pathogenicity into a near commensal bacteria in poultry. Birds are usually infected from two to four weeks of age and remain colonized until they reach market age. A small dose of C. jejuni (around 35 CFU/mL) is sufficient for successful bird colonization. In the U.S., where chickens are raised under antibiotic-free environments, additional strategies are required to reduce C. jejuni prevalence on broilers farms. Strict biosecurity measures can decrease C. jejuni prevalence by more than 50% in broilers at market age. Vaccination and probiotics, prebiotics, synbiotics, organic acids, bacteriophages, bacteriocins, and quorum sensing inhibitors supplementation can improve gut health and competitively exclude C. jejuni load in broilers. Most of the mentioned strategies showed promising results; however, they are not fully implemented in poultry production. Current knowledge on C. jejuni's morphology, source of transmission, pathogenesis in poultry, and available preharvest strategies to decrease C. jejuni colonization in broilers are addressed in this review.

Lactobacilli, a Weapon to Counteract Pathogens through the Inhibition of Their Virulence Factors

To date, several studies have reported an alarming increase in pathogen resistance to current antibiotic therapies and treatments. Therefore, the search for effective alternatives to counter their spread and the onset of infections is becoming increasingly important.

Bacillus subtilis PS-216 Spores Supplemented in Broiler Chicken Drinking Water Reduce Campylobacter jejuni Colonization and Increases Weight Gain

Campylobacter jejuni is the leading cause of bacterial gastroenteritis, or campylobacteriosis, in humans worldwide, and poultry serves as a major source of infection. To reduce the risk associated with C. jejuni transmission via poultry meat, effective interventions during poultry production are needed, and the use of probiotics is a promising approach. In this study, 15 Bacillus subtilis strains were initially screened for their anti-Campylobacter activities. B. subtilis PS-216 strain demonstrated the best anti-Campylobacter activity against 15 C. jejuni isolates when examined using in vitro co-cultures. To evaluate the suitability of B. subtilis PS-216 for probiotic use, its susceptibility to eight clinically important antimicrobials and simulated gastric conditions was investigated. B. subtilis PS-216 was sensitive to all of the tested antibiotics. Although vegetative cells were sensitive to gastric conditions, B. subtilis PS-216 spores were highly resistant. We further evaluated the use of a B. subtilis PS-216 spore preparation (2.5 × 106 CFU/mL water) to prevent and/or reduce C. jejuni colonization in broiler chickens in vivo. Compared to the untreated group, significantly lower Campylobacter counts were detected in caeca of broilers continuously treated with B. subtilis PS-216 spores in their drinking water. Furthermore, broilers continuously treated with B. subtilis PS-216 spores showed improved weight gain, compared to the control group. Together, these results demonstrate the potential of B. subtilis PS-216 for use in poultry to reduce C. jejuni colonization and improve weight gain.

Lactiplantibacillus plantarum 1201 Inhibits Intestinal Infection of Salmonella enterica subsp. enterica Serovar Typhimurium Strain ATCC 13311 in Mice with High-Fat Diet

Salmonella Typhimurium is widely distributed in food. It can colonise the gastrointestinal tract after ingestion, causing lamina propria edema, inflammatory cell infiltration, and mucosal epithelial decomposition. A high-fat diet (HFD) can induce an inflammatory response, but whether HFD can increase the infection level of S. Typhimurium is unknown. We established a model of Salmonella enterica subsp. enterica serovar Typhimurium strain ATCC 13311 ATCC 13311 infection in healthy adult mice with a maintenance diet (MD) or HFD to explore the effect of Lactiplantibacillus plantarum 1201 intervention on S. Typhimurium ATCC 13311 colonization and its protective effects on mice. HFD exacerbated the infection of S. Typhimurium ATCC 13311, while the intervention of L. plantarum 1201 effectively mitigated this process. L. plantarum 1201 can reduce the colonies of S. ATCC 13311 in the intestines and tissues; and reduce intestinal inflammation by down-regulating the level of TLR4/NF-κB pathway related proteins in serum and the expression of related inflammatory factors in the colon and jejunum. Since L. plantarum 1201 can inhibit the colonization of S. Typhimurium ATCC 13311 and relieve inflammation in HFD, current research may support the use of L. plantarum 1201 to prevent S. Typhimurium infection.

A Review of the Effects and Production of Spore-Forming Probiotics for Poultry

Simple Summary

Spore-forming probiotics are widely used in the poultry industry for their beneficial impact on host health. The main feature that separates spore-forming probiotics from the more common lactic acid probiotics is their high resistance to external and internal factors, resulting in higher viability in the host and correspondingly, greater efficiency. Their most important effect is the ability to confront pathogens, which makes them a perfect substitute for antibiotics. In this review, we cover and discuss the interactions of spore-forming probiotic bacteria with poultry as the host, their health promotion effects and mechanisms of action, impact on poultry productivity parameters, and ways to manufacture the probiotic formulation. The key focus of this review is the lack of reproducibility in poultry research studies on the evaluation of probiotics’ effects, which should be solved by developing and publishing a set of standard protocols in the professional community for conducting probiotic trials in poultry.

Abstract

One of the main problems in the poultry industry is the search for a viable replacement for antibiotic growth promoters. This issue requires a “one health” approach because the uncontrolled use of antibiotics in poultry can lead to the development of antimicrobial resistance, which is a concern not only in animals, but for humans as well. One of the promising ways to overcome this challenge is found in probiotics due to their wide range of features and mechanisms of action for health promotion. Moreover, spore-forming probiotics are suitable for use in the poultry industry because of their unique ability, encapsulation, granting them protection from the harshest conditions and resulting in improved availability for hosts’ organisms. This review summarizes the information on gastrointestinal tract microbiota of poultry and their interaction with commensal and probiotic spore-forming bacteria. One of the most important topics of this review is the absence of uniformity in spore-forming probiotic trials in poultry. In our opinion, this problem can be solved by the creation of standards and checklists for these kinds of trials such as those used for pre-clinical and clinical trials in human medicine. Last but not least, this review covers problems and challenges related to spore-forming probiotic manufacturing.

Bacillaene Mediates the Inhibitory Effect of Bacillus subtilis on Campylobacter jejuni Biofilms

Biofilms are the predominant bacterial lifestyle and can protect microorganisms from environmental stresses. Multispecies biofilms can affect the survival of enteric pathogens that contaminate food products, and thus, investigating the underlying mechanisms of multispecies biofilms is essential for food safety and human health. In this study, we investigated the ability of the natural isolate Bacillus subtilis PS-216 to restrain Campylobacter jejuni biofilm formation and adhesion to abiotic surfaces as well as to disrupt preestablished C. jejuni biofilms. Using confocal laser scanning microscopy and colony counts, we demonstrate that the presence of B. subtilis PS-216 prevents C. jejuni biofilm formation, decreases growth of the pathogen by 4.2 log₁₀, and disperses 26-h-old preestablished C. jejuni biofilms. Furthermore, the coinoculation of B. subtilis and C. jejuni interferes with the adhesion of C. jejuni to abiotic surfaces, reducing it by 2.4 log₁₀. We also show that contact-independent mechanisms contribute to the inhibitory effect of B. subtilis PS-216 on C. jejuni biofilm. Using B. subtilis mutants in genes coding for nonribosomal peptides and polyketides revealed that bacillaene significantly contributes to the inhibitory effect of B. subtilis PS-216. In summary, we show a strong potential for the use of B. subtilis PS-216 against C. jejuni biofilm formation and adhesion to abiotic surfaces. Our research could bring forward novel applications of B. subtilis in animal production and thus contribute to food safety. IMPORTANCE Campylobacter jejuni is an intestinal commensal in animals (including broiler chickens) but also the most frequent cause of bacterial foodborne infection in humans. This pathogen forms biofilms which enhance survival of C. jejuni in food processing and thus threaten human health. Probiotic bacteria represent a potential alternative in the prevention and control of foodborne infections. The beneficial bacterium Bacillus subtilis has an excellent probiotic potential to reduce C. jejuni in the animal gastrointestinal tract. However, data on the effect of B. subtilis on C. jejuni biofilms are scarce. Our study shows that the B. subtilis natural isolate PS-216 prevents adhesion to the abiotic surfaces and the development of submerged C. jejuni biofilm during coculture and destroys the preestablished C. jejuni biofilm. These insights are important for development of novel applications of B. subtilis that will reduce the use of antibiotics in human and animal health and increase productivity in animal breeding.

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 Bacillus cereus Food Infection as Multifactorial Process

The ubiquitous soil bacterium Bacillus cereus presents major challenges to food safety. It is responsible for two types of food poisoning, the emetic form due to food intoxication and the diarrheal form emerging from food infections with enteropathogenic strains, also known as toxico-infections, which are the subject of this review. The diarrheal type of food poisoning emerges after production of enterotoxins by viable bacteria in the human intestine. Basically, the manifestation of the disease is, however, the result of a multifactorial process, including B. cereus prevalence and survival in different foods, survival of the stomach passage, spore germination, motility, adhesion, and finally enterotoxin production in the intestine. Moreover, all of these processes are influenced by the consumed foodstuffs as well as the intestinal microbiota which have, therefore, to be considered for a reliable prediction of the hazardous potential of contaminated foods. Current knowledge regarding these single aspects is summarized in this review aiming for risk-oriented diagnostics for enteropathogenic B. cereus.

Strategies and novel technologies to control Campylobacter in the poultry chain: A review

Campylobacteriosis is one of the most common bacterial infections worldwide causing economic costs. The high prevalence of Campylobacter spp. in poultry meat is a result of several contamination and cross-contamination sources through the production chain. Moreover, survival mechanisms, such as biofilm formation, viable but nonculturable state, and antimicrobial resistance, enable its persistence during food processing. Therefore, mitigation strategies are necessary in order to avoid and/or inactivate Campylobacter at farm, abattoir, industry, and retail level. In this review, a number of potential strategies and novel technologies that could reduce the prevalence of Campylobacter in poultry meat have been identified and evaluated to provide a useful overview. At farm level for instance, biosecurity, bacteriocins, probiotics, feed and water additives, bacteriophages, and vaccination could potentially reduce colonization in chicken flocks. However, current technologies used in the chicken slaughter and processing industry may be less effective against this foodborne pathogen. Novel technologies and strategies such as cold plasma, ultraviolet light, high-intensity light pulses, pulsed electric fields, antimicrobials, and modified atmosphere packaging are discussed in this review for reducing Campylobacter contamination. Although these measures have achieved promising results, most have not been integrated within processing operations due to a lack of knowledge or an unwillingness to implement these into existing processing systems. Furthermore, a combination of existing and novel strategies might be required to decrease the prevalence of this pathogen in poultry meat and enhance food safety. Therefore, further research will be essential to assess the effectiveness of all these strategies.

Effect of Lactobacillus spp. on adhesion, invasion, and translocation of Campylobacter jejuni in chicken and pig small-intestinal epithelial cell lines

BACKGROUND

Campylobacter spp. are a major cause of bacterial food-borne diarrhoeal disease. This mainly arises through contamination of meat products during processing. For infection, Campylobacter spp. must adhere to epithelial cells of the mucus layer, survive conditions of the gastrointestinal tract, and colonise the intestine of the host. Addition of probiotic bacteria might promote competitive adhesion to epithelial cells, consequently reducing Campylobacter jejuni colonisation. Effect of Lactobacillus spp. (PCS20, PCS22, PCS25, LGG, PCK9) on C. jejuni adhesion, invasion and translocation in pig (PSI cl.1) and chicken (B1OXI) small-intestine cell lines, as well as pig enterocytes (CLAB) was investigated.

RESULTS

Overall, in competitive adhesion assays with PSI cl.1 and CLAB cell monolayers, the addition of Lactobacillus spp. reduced C. jejuni adherence to the cell surface, and negatively affected the C. jejuni invasion. Interestingly, Lactobacillus spp. significantly impaired C. jejuni adhesion in three-dimensional functional PSI cl.1 and B1OXI cell models. Also, C. jejuni did not translocate across PSI cl.1 and B1OXI cell monolayers when co-incubated with probiotics. Among selected probiotics, Lactobacillus rhamnosus LGG was the strain that reduced adhesion efficacy of C. jejuni most significantly under co-culture conditions.

CONCLUSION

The addition of Lactobacillus spp. to feed additives in livestock nutrition might be an effective novel strategy that targets Campylobacter adhesion to epithelial cells, and thus prevents colonisation, reduces the transmission, and finally lowers the incidence of human campylobacteriosis.

Campylobacter Abundance in Breastfed Infants and Identification of a New Species in the Global Enterics Multicenter Study

Campylobacter jejuni is a leading cause of bacterial diarrhea worldwide and is associated with high rates of mortality and growth stunting in children inhabiting low- to middle-resource countries. To better understand the impact of breastfeeding on Campylobacter infection in infants in sub-Saharan Africa and South Asia, we examined fecal microbial compositions, bacterial isolates, and their carbohydrate metabolic pathways in Campylobacter-positive infants <1 year of age from the Global Enterics Multicenter Study. Exclusively breastfed infants with diarrhea exhibited high Campylobacter abundances, and this negatively correlated with bacterial carbohydrate metabolism. Although C. jejuni and Campylobacter coli are prevalent among these infants, the second most abundant Campylobacter species was a new species, which we named "Candidatus Campylobacter infans." Asymptomatic Campylobacter carriers also possess significantly different proportions of specific gut microbes compared to diarrheal cases. These findings provide insight into Campylobacter infections in infants in sub-Saharan Africa and South Asia and help inform strategies aimed at eliminating campylobacteriosis in these areas.IMPORTANCECampylobacter is the primary cause of bacterial diarrhea in the United States and can lead to the development of the postinfectious autoimmune neuropathy known as Guillain-Barré syndrome. Also, drug-resistant campylobacters are becoming a serious concern both locally and abroad. In low- and middle-income countries (LMICs), infection with Campylobacter is linked to high rates of morbidity, growth stunting, and mortality in children, and breastfeeding is important for infant nutrition, development, and protection against infectious diseases. In this study, we examined the relationship between breastfeeding and Campylobacter infection and demonstrate the increased selection for C. jejuni and C. coli strains unable to metabolize fucose. We also identify a new Campylobacter species coinfecting these infants with a high prevalence in five of the seven countries in sub-Saharan Africa and South Asia examined. These findings indicate that more detailed studies are needed in LMICs to understand the Campylobacter infection process in order to devise a strategy for eliminating this pathogenic microbe.

In vitro assessment of immunomodulatory and anti-Campylobacter activities of probiotic lactobacilli

The present study was undertaken to assess the antimicrobial activity of Lactobacillus spp. (L. salivarius, L. johnsonii, L. reuteri, L. crispatus, and L. gasseri) against Campylobacter jejuni as well as their immunomodulatory capabilities. The results demonstrated that lactobacilli exhibit differential antagonistic effects against C. jejuni and vary in their ability to elicit innate responses in chicken macrophages. All lactobacilli exerted inhibitory effects on C. jejuni growth, abrogated the production of the quorum sensing molecule autoinducer-2 (AI-2) by C. jejuni and inhibited the invasion of C. jejuni in human intestinal epithelial cells. Additionally, all lactobacilli, except L. reuteri, significantly reduced the expression of virulence-related genes in C. jejuni, including genes responsible for motility (flaA, flaB, and flhA), invasion (ciaB), and AI-2 production (luxS). All lactobacilli enhanced C. jejuni phagocytosis by macrophages and increased the expression of interferon (IFN)-γ, interleukin (IL)-1β, IL-12p40, IL-10, and chemokine (CXCLi2) in macrophages. Furthermore, L. salivarius, L. reuteri, L. crispatus, and a mixture of all lactobacilli significantly increased expression of the co-stimulatory molecules CD40, CD80, and CD86 in macrophages. In conclusion, these findings demonstrate that lactobacilli possess anti-Campylobacter and immunomodulatory activities. Further studies are needed to assess their protective efficacy against intestinal colonization by C. jejuni in broiler chickens.

SCFAs-Induced GLP-1 Secretion Links the Regulation of Gut Microbiome on Hepatic Lipogenesis in Chickens

The impact of gut microbiota and its metabolites on fat metabolism have been widely reported in human and animals. However, the critical mediators and the signal transductions are not well demonstrated. As ovipara, chicken represents a specific case in lipid metabolism that liver is the main site of lipid synthesis. The aim of this study is to elucidate the linkage of gut microbiota and fat synthesis in broiler chickens. The broilers were subjected to dietary treatments of combined probiotics (Animal bifidobacterium: 4 × 10⁸ cfu/kg; Lactobacillus plantarum: 2 × 10⁸ cfu/kg; Enterococcus faecalis: 2 × 10⁸ cfu/kg; Clostridium butyrate: 2 × 10⁸ cfu/kg, PB) and guar gum (1 g/kg, GG), respectively. Results showed that dietary supplementation of PB and GG changed the cecal microbiota diversity, altered short chain fatty acids (SCFAs) contents, and suppressed lipogenesis. In intestinal epithelial cells (IECs), SCFAs (acetate, propionate, and butyrate) up-regulated the expression of glucagon-like peptide-1 (GLP-1) via mitogen-activated protein kinase (MAPK) pathways, mainly via the phospho - extracellular regulated protein kinase (ERK) and phospho-p38 mitogen activated protein kinase (p38 MAPK) pathways. GLP-1 suppressed lipid accumulation in primary hepatocytes with the involvement of (AMP)-activated protein kinase/Acetyl CoA carboxylase (AMPK/ACC) signaling. In conclusion, the result suggests that SCFAs-induced GLP-1 secretion via MAPK pathway, which links the regulation of gut microbiota on hepatic lipogenesis in chickens.

In vitro efficacy of potentiated egg yolk powder against Campylobacter jejuni does not correlate with in vitro efficacy

Campylobacter jejuni is a zoonotic agent responsible for the foodborne gastroenteritis campylobacteriosis. Control of C. jejuni load in the poultry primary production is recognized as an avenue to reduce human exposure to the pathogen. As for now, no commercially applicable control methods exist at the farm. Several studies tested egg yolk powders, potentiated or not against C. jejuni, as feed additives for chicken and suggested that the quantity and quality of the antibodies presence in the yolk are determinant factors for the full success of this approach. Unfortunately, data from these studies inconsistently showed a reduction of cecal C. jejuni carriage. Our first goal wwas to characterize (quantification by ELISA, agglutination test, bacterial antigen recognition profiles by Western blot, bactericidal effect by serum killing assays and C. jejuni mobility by soft agar migation) the antibodies extracted from egg yolk powders originating from different egg production protocols. Secondly, these powders were microencapsulated and recharacterized. Finally the protected powders were tested as a feed additive to destabilize C. jejuni colonization in an in vivo assay. Despite the in vitro results indicating the ability of the egg yolk powders to recognize Campylobacter and potentially alter its colonization of the chicken caecum, these results were not confirmed in the in vivo trial despite that specific caecal IgY directed toward Campylobacter were detected in the groups receiving the protected powders. More research is needed on Campylobacter in order to effectively control this pathogen at the farm.

Probiotics interaction with foodborne pathogens: a potential alternative to antibiotics and future challenges

Antibiotics are a key tool used nowadays in health care industry to fight against bacterial infections; however, repeated antibiotic use or misuses, have led to bacterial resistance, causing significant threats for many people with common bacterial infections. The use of probiotics to enhance gastrointestinal health has been proposed for many years. In recent years, there has been an increasing interest in the use of probiotic bacteria as alternatives for antibiotics for preventing or treating various intestinal infections. Several important underlying mechanisms responsible for the antagonistic effects of probiotics on different microorganisms include: (1) competitive exclusion for adhesion sites and nutritional sources; (2) secretion of antimicrobial substances; (3) enhancement of intestinal barrier function; and (4) immunomodulation. However, their mode of action is not very well understood and therefore a clearer understanding of these mechanisms is necessitated. This will enable appropriate probiotic strains to be selected for particular applications and may reveal new probiotic functions. The goal of this review was to highlight some studies from literature describing the probiotic interaction with several major foodborne pathogens, as well as explore the mechanisms for such probiotic-pathogen interaction. The review will conclude by presenting future perspective and challenges of probiotic application in food products.

At-hatch administration of probiotic to chickens can introduce beneficial changes in gut microbiota

Recent advances in culture-free microbiological techniques bring new understanding of the role of intestinal microbiota in heath and performance. Intestinal microbial communities in chickens assume a near-stable state within the week which leaves a very small window for permanent microbiota remodelling. It is the first colonisers that determine the fate of microbial community in humans and birds alike, and after the microbiota has matured there are very small odds for permanent modification as stable community resists change. In this study we inoculated broiler chicks immediately post hatch, with 3 species of Lactobacillus, identified by sequencing of 16S rRNA and pheS genes as L. ingluviei, L. agilis and L. reuteri. The strains were isolated from the gut of healthy chickens as reproducibly persistent Lactobacillus strains among multiple flocks. Birds inoculated with the probiotic mix reached significantly higher weight by 28 days of age. Although each strain was able to colonise when administered alone, administering the probiotic mix at-hatch resulted in colonisation by only L. ingluviei. High initial abundance of L. ingluviei was slowly reducing, however, the effects of at-hatch administration of the Lactobacillus mix on modifying microbiota development and structure remained persistent. There was a tendency of promotion of beneficial and reduction in pathogenic taxa in the probiotic administered group.

The influence of probiotic supplementation in broiler chickens on population and carcass contamination with Campylobacter spp. - Field study

Campylobacter spp. is a food-borne pathogen occurring all over the world. According to European Food Safety Authority, in Europe, in 2015 the number of recorded and confirmed cases of Campylobacter spp. infections in humans has reached approximately 230,000. Poultry and poultry meat are considered to be the main sources of human infection, which triggers the discussion about the possibility of imposing obligatory control of Campylobacter spp. population at the level of primary poultry production. Recently, the use of probiotics in poultry is considered as a very promising alternative that could reduce infection rate in broiler chickens with Campylobacter spp. Although, there were some approaches made in vivo, up to date, there were no studies that would evaluate those issues under field conditions. A study was carried out in order to determine the feasibility of reducing infection rate in broiler chickens with Campylobacter spp. raised at a commercial farm, by the addition of multispecies probiotic (Lavipan, JHJ, Poland) that composed of Lactococcus lactis, Carnobacterium divergens, Lactobacillus casei, Lactobacillus plantarum and Saccharomyces cerevisae to the feed. Results of our study indicate that probiotic (Lavipan) added to a feed for broiler chickens was capable to reduce the extent of Campylobacter spp. invasion in the gastrointestinal tract of birds and, resultantly, to diminish contamination level in bird environment, which eventually contributed to the improved hygienic parameters of analyzed poultry carcasses. Additionally, this probiotic displayed promising immunomodulatory properties that may improve the effectiveness of the specific prophylaxis program applied in a flock of broiler chickens.

In Vitro Evaluation of the Impact of the Probiotic E. coli Nissle 1917 on Campylobacter jejuni's Invasion and Intracellular Survival in Human Colonic Cells

Campylobacter jejuni is a leading cause of bacterial food poisoning in humans. Due to the rise in antibiotic-resistant Campylobacter, there exists a need to develop antibiotic-independent interventions to control infections in humans. Here, we evaluated the impact of Escherichia coli Nissle 1917 (EcN), a probiotic strain, on C. jejuni’s invasion and intracellular survival in polarized human colonic cells (HT-29). To further understand how EcN mediates its impact, the expression of 84 genes associated with tight junctions and cell adhesion was profiled in HT-29 cells after treatment with EcN and challenge with C. jejuni. The pre-treatment of polarized HT-29 cells with EcN for 4 h showed a significant effect on C. jejuni’s invasion (∼2 log reduction) of the colonic cells. Furthermore, no intracellular C. jejuni were recovered from EcN pre-treated HT-29 cells at 24 h post-infection. Other probiotic strains tested had no significant impact on C. jejuni invasion and intracellular survival. C. jejuni decreased the expression of genes associated with epithelial cells permeability and barrier function in untreated HT-29 cells. However, EcN positively affected the expression of genes that are involved in enhanced intestinal barrier function, decreased cell permeability, and increased tight junction integrity. The results suggest that EcN impedes C. jejuni invasion and subsequent intracellular survival by affecting HT-29 cells barrier function and tight junction integrity. We conclude that EcN might be a viable alternative for controlling C. jejuni infections.

Transplanted human fecal microbiota enhanced Guillain Barré syndrome autoantibody responses after Campylobacter jejuni infection in C57BL/6 mice

BACKGROUND

Campylobacter jejuni is the leading antecedent infection to the autoimmune neuropathy Guillain-Barré syndrome (GBS), which is accompanied by an autoimmune anti-ganglioside antibody attack on peripheral nerves. Previously, we showed that contrasting immune responses mediate C. jejuni induced colitis and autoimmunity in interleukin-10 (IL-10)-deficient mice, dependent upon the infecting strain. Strains from colitis patients elicited T helper 1 (T_H1)-dependent inflammatory responses while strains from GBS patients elicited T_H2-dependent autoantibody production. Both syndromes were exacerbated by antibiotic depletion of the microbiota, but other factors controlling susceptibility to GBS are unknown.

METHODS

Using 16S rRNA gene high-throughput sequencing, we examined whether structure of the gut microbial community alters host (1) gastrointestinal inflammation or (2) anti-ganglioside antibody responses after infection with C. jejuni strains from colitis or GBS patients. We compared these responses in C57BL/6 mice with either (1) stable human gut microbiota (^Humicrobiota) transplants or (2) conventional mouse microbiota (^Convmicrobiota).

RESULTS

Inoculating germ-free C57BL/6 wild-type (WT) mice with a mixed human fecal slurry provided a murine model that stably passed its microbiota over >20 generations. Mice were housed in specific pathogen-free (SPF) facilities, while extra precautions of having caretakers wear sterile garb along with limited access ensured that no mouse pathogens were acquired. ^Humicrobiota conferred many changes upon the WT model in contrast to previous results, which showed only colonization with no disease after C. jejuni challenge. When compared to ^Convmicrobiota mice for susceptibility to C. jejuni enteric or GBS patient strains, infected ^Humicrobiota mice had (1) 10-100 fold increases in C. jejuni colonization of both strains, (2) pathologic change in draining lymph nodes but only mild changes in colon or cecal lamina propria, (3) significantly lower Th1/Th17-dependent anti-C. jejuni responses, (4) significantly higher IL-4 responses at 5 but not 7 weeks post infection (PI), (5) significantly higher Th2-dependent anti-C. jejuni responses, and (6) significantly elevated anti-ganglioside autoantibodies after C. jejuni infection. These responses in ^Humicrobiota mice were correlated with a dominant Bacteroidetes and Firmicutes microbiota.

CONCLUSIONS

These data demonstrate that ^Humicrobiota altered host-pathogen interactions in infected mice, increasing colonization and Th-2 and autoimmune responses in a C. jejuni strain-dependent manner. Thus, microbiota composition is another factor controlling susceptibility to GBS.

Administration of Lactobacillus johnsonii FI9785 to chickens affects colonisation by Campylobacter jejuni and the intestinal microbiota

1. Campylobacter jejuni is the most common bacterial cause of human food-borne gastroenteritis in the world. A major source of human infection is the consumption of contaminated meat, particularly poultry. New control measures to reduce or eliminate this pathogen from the animal gastrointestinal tract are urgently required, and the use of probiotics as competitive exclusion agents is a promising biocontrol measure to reduce C. jejuni in the food chain. 2. In this study, we assessed the potential of Lactobacillus johnsonii FI9785, which has shown efficacy against Clostridium perfringens, to combat C. jejuni. The effect of prophylactic administration of L. johnsonii on the ability of C. jejuni to colonise chickens was determined. 3. Two doses of L. johnsonii given a week apart led to a reduction in C. jejuni colonisation in the caecal contents, but this biocontrol seemed reliant upon a high level of initial colonisation by the probiotic. 4. The microbial composition in the chicken gut was significantly altered by the probiotic treatment, as shown by denaturing gradient gel electrophoresis of 16S rRNA gene amplicons. 5. Together these results demonstrate the potential of this probiotic strain to be tested further as a competitive exclusion agent in poultry against C. jejuni.

Current and Potential Treatments for Reducing Campylobacter Colonization in Animal Hosts and Disease in Humans

Campylobacter jejuni is the leading cause of bacteria-derived gastroenteritis worldwide. In the developed world, Campylobacter is usually acquired by consuming under-cooked poultry, while in the developing world it is often obtained through drinking contaminated water. Once consumed, the bacteria adhere to the intestinal epithelium or mucus layer, causing toxin-mediated inhibition of fluid reabsorption from the intestine and invasion-induced inflammation and diarrhea. Traditionally, severe or prolonged cases of campylobacteriosis have been treated with antibiotics; however, overuse of these antibiotics has led to the emergence of antibiotic-resistant strains. As the incidence of antibiotic resistance, emergence of post-infectious diseases, and economic burden associated with Campylobacter increases, it is becoming urgent that novel treatments are developed to reduce Campylobacter numbers in commercial poultry and campylobacteriosis in humans. The purpose of this review is to provide the current status of present and proposed treatments to combat Campylobacter infection in humans and colonization in animal reservoirs. These treatments include anti-Campylobacter compounds, probiotics, bacteriophage, vaccines, and anti-Campylobacter bacteriocins, all of which may be successful at reducing the incidence of campylobacteriosis in humans and/or colonization loads in poultry. In addition to reviewing treatments, we will also address several proposed targets that may be used in future development of novel anti-Campylobacter treatments.

Potential of Zimbabwean commercial probiotic products and strains of Lactobacillus plantarum as prophylaxis and therapy against diarrhoea caused by Escherichia coli in children

OBJECTIVE

To evaluate the potential of commercial fermented products sold in the country, and strains of Lactobacillus plantarum (L. plantarum) as prophylaxis and therapy against diarrhoea in children.

METHODS

The antimicrobial potential of cultures of lactobacilli enriched from 4 Zimbabwean commercial food/beverage products: Dairibord Lacto sour milk (DLSM), Probrand sour milk (PSM), Kefalos Vuka cheese (KVC) and Chibuku opaque beer (COB); and four strains of L. plantarum obtained from Balkan traditional cheeses against clinical strains of Escherichia coli (E. coli) was assayed using the well diffusion method. Three commercial paediatric antidiarrhoeal drug products: Biogaia (BG), Prolife (PL) and Probio Junior (PJ) and a mutant strain of E. coli [strain 11105 (ATCC) - a vitamin B-12 auxotroph and penicillin G acylase-producing strain] were used as controls. An agar diffusion assay and a competitive exclusion assay were carried out on Mueller Hinton agar.

RESULTS

Crude cultures of putative lactobacillus strains obtained from Zimbabwean dairy products (Probrand sour milk, Kefalos Vuka vuka cheese and Chibuku opaque beer) had significantly higher antimicrobial activities against clinical strains of E. coli than strains of L. plantarum isolated from Balkan cheeses (CLP1, CLP2 or CLP3) and crude microbial cultures from commercial paediatric probiotic products (BG, PJ and PL) of a culture of Lactobacillus rhamnosus LGG (P < 0.05).

CONCLUSIONS

The putative Lactobacilli from four commercial Zimbabwean dairy products (Probrand sour milk, Kefalos Vuka vuka cheese and Chibuku opaque beer), and three strains of L. plantarum from Balkan cheeses (CLP1, CLP2 or CLP3) exhibited high antibacterial activities that can be harnessed to control paediatric diarrhoea that is caused by pathogenic strains of E. coli. Studies to characterise the probiotic potential of the live cultures in the products and the new strains of L. plantarum are underway.

Recent Advances in Screening of Anti-Campylobacter Activity in Probiotics for Use in Poultry

Campylobacteriosis is the most common cause of bacterial gastroenteritis worldwide. Campylobacter species involved in this infection usually include the thermotolerant species Campylobacter jejuni. The major reservoir for C. jejuni leading to human infections is commercial broiler chickens. Poultry flocks are frequently colonized by C. jejuni without any apparent symptoms. Risk assessment analyses have identified the handling and consumption of poultry meat as one of the most important sources of human campylobacteriosis, so elimination of Campylobacter in the poultry reservoir is a crucial step in the control of this foodborne infection. To date, the use of probiotics has demonstrated promising results to reduce Campylobacter colonization. This review provides recent insights into methods used for probiotic screening to reduce the prevalence and colonization of Campylobacter at the farm level. Different eukaryotic epithelial cell lines are employed to screen probiotics with an anti-Campylobacter activity and yield useful information about the inhibition mechanism involved. These in vitro virulence models involve only human intestinal or cervical cell lines whereas the use of avian cell lines could be a preliminary step to investigate mechanisms of C. jejuni colonization in poultry in the presence of probiotics. In addition, in vivo trials to evaluate the effect of probiotics on Campylobacter colonization are conducted, taking into account the complexity introduced by the host, the feed, and the microbiota. However, the heterogeneity of the protocols used and the short time duration of the experiments lead to results that are difficult to compare and draw conclusions at the slaughter-age of broilers. Nevertheless, the combined approach using complementary in vitro and in vivo tools (cell cultures and animal experiments) leads to a better characterization of probiotic strains and could be employed to assess reduced Campylobacter spp. colonization in chickens if some parameters are optimized.

PCR-RFLP Provides Discrimination for Total flaA Sequence Analysis in Clinical Campylobacter jejuni Isolates

The aims of this study were to determine the genetic relatedness among 20 clinical Campylobacter jejuni samples isolated from children with diarrhea in Iran and to introduce the best method of discrimination based on flagellin gene (flaA) sequence divergence. A total of 400 stool specimens were obtained from children under 5 years of age from July 2012 to June 2013. Primers were designed based on conserved sequences flanking the flaA gene that encompassed and amplified the entire flaA gene and followed by sequencing and data analysis with MEGA version 6.0.6 software. Ninety amino acids and 560 nucleotide polymorphic sequences were detected within 1,681 bp of the flaA sequence of which 43 (2.5%) and 12 (0.7%) were singletons, respectively. New repeat boxes within the flaA sequences were found in this study. Unweighted Pair Group Method with Arithmetic Mean dendrogram based on nucleotides of the full length flaA gene, the flaA short variable region gene and the in silico flaA phylogenic tree of DdeI restriction fragment length polymorphism (RFLP) profiles produced very similar clustering with a diversity index of 0.86 for each of the 3 methods. We conclude that flaA typing based on DdeI RFLP of the PCR products is a cheap, rapid, and reliable method for the epidemiological study of C. jejuni isolates of clinical origin in resource-limited regions or in large-scale population surveillance.