Predisposing factors and prevention of Clostridium perfringens-associated enteritis

Integrated multi-omics reveals the Bacillus amyloliquefaciens BA40 against Clostridium perfringens infection in weaned piglets

INTRODUCTION

Clostridium perfringens (C. perfringens) can cause necrotic enteritis and higher mortality rates in piglets, by impairing the intestinal barrier function. Bacillus amyloliquefaciens 40 (BA40) has showed potential ability to reduce C. perfringens infections, but the mechanisms responsible for its effectiveness remain unclear.

OBJECTIVES

This study aims to evaluate the impact of BA40 on inflammation induced by C. perfringens and to explain the mechanisms underlying its therapeutic effects. We aim to show how BA40 can bolster piglet health by strengthening the intestinal barrier and regulating immune responses.

METHODS

We used piglets and cellular models, alongside microbiomics, metabolomic, and transcriptomic analyses, to investigate BA40's impact on C. perfringens-induced inflammation. A model of C. perfringens infection was constructed using piglets and cells to investigate the effect of BA40 on its phenotype. Microbiomics, metabolomics, and transcriptomics analyses were subsequently used to investigate the mechanisms of protection and immune response to BA40 on the intestinal barrier of piglets.

RESULTS

Our study revealed significant improvements in piglet health following BA40 administration. Notably, BA40 strengthened the intestinal mucosal barrier and mitigated the inflammatory response triggered by C. perfringens BA40 decreased harmful bacteria and increased beneficial bacteria. Metabolite profiles improved, showing a reduction in harmful substances. Transscriptomics analysis indicated BA40's role in TNF/NF-κB signaling pathway, hinting at its ability to regulate immune responses and reduce intestinal inflammation. Cellular assays further confirmed BA40's capacity to diminish inflammatory cytokine release and encourage the differentiation of anti-inflammatory macrophages.

CONCLUSION

Datasets from the present study demonstrate that BA40 modulates gut microbes and metabolites, inhibits inflammation-related signaling pathways, and maintains gut barrier function. Our findings not only deepen our understanding of the therapeutic capacity of BA40 but also provide a theoretical foundation for the development of probiotics and alternative therapies aimed at improving piglet gut health.

Application of antimicrobial peptides in the poultry industry

Poultry meat production and exportation contribute significantly to the global economy. However, various infections affect poultry production and consequently affect the economy. Nowadays, antibiotics are widely used in infection treatment and prevention. Antibiotic overuse is problematic because may cause antimicrobial resistance, which can be transferred to humans directly or indirectly, affecting public health. In addition, since antibiotics for animal growth stimulation are banned, it is important to search for new molecules to overcome these difficulties. As an alternative, antimicrobial peptides (AMPs) can show immunomodulatory, antimicrobial, and growth stimulation, which makes these molecules interesting as alternatives to antibiotic use. Studying AMPs can provide new ideas for treating the most important infections that affect poultry. Besides, this can assist in reducing the resistance problem. This review aims to examine recent studies about AMPs used against pathogens that can affect the poultry industry.

Antimicrobial peptides in livestock: a review with a one health approach

Antimicrobial peptides (AMPs), often referred to as nature's antibiotics, are ubiquitous in living organisms, spanning from bacteria to humans. Their potency, versatility, and unique mechanisms of action have garnered significant research attention. Unlike conventional antibiotics, peptides are biodegradable, adding to their appeal as potential candidates to address bacterial resistance in livestock farming-a challenge that has been under scrutiny for decades. This issue is complex and multifactorial, influenced by a variety of components. The World Health Organization (WHO) has proposed a comprehensive approach known as One Health, emphasizing the interconnectedness of human-animal-environment relationships in tackling such challenges. This review explores the application of AMPs in livestock farming and how they can mitigate the impact of this practice within the One Health framework.

Clostridium perfringens-Opportunistic Foodborne Pathogen, Its Diversity and Epidemiological Significance

The C. perfringens species is associated with various environments, such as soils, sewage, and food. However, it is also a component of the gastrointestinal (GI) microflora (i.e., microbiota) of sick and healthy humans and animals. C. perfringens is linked with different systemic and enteric diseases in livestock and humans, such as gas gangrene, food poisoning, non-foodborne diarrhoea, and enterocolitis. The strains of this opportunistic pathogen are known to secrete over 20 identified toxins that are considered its principal virulence factors. C. perfringens belongs to the anaerobic bacteria community but can also survive in the presence of oxygen. The short time between generations, the multi-production capability of toxins and heat-resistant spores, the location of many virulence genes on mobile genetic elements, and the inhabitance of this opportunistic pathogen in different ecological niches make C. perfringens a very important microorganism for public health protection. The epidemiological evidence for the association of these strains with C. perfringens-meditated food poisoning and some cases of non-foodborne diseases is very clear and well-documented. However, the genetic diversity and physiology of C. perfringens should still be studied in order to confirm the importance of suspected novel virulence traits. A very significant problem is the growing antibiotic resistance of C. perfringens strains. The aim of this review is to show the current basic information about the toxins, epidemiology, and genetic and molecular diversity of this opportunistic pathogen.

Phenotypical Identification and Toxinotyping of Clostridium perfringens Isolates from Healthy and Enteric Disease-Affected Chickens

Clostridium perfringens is a ubiquitous spore-forming anaerobic pathogen that is frequently associated with enteric disease in chickens. Moreover, enterotoxin-producing C. perfringens has high zoonotic potential as well as serious public health concerns due to the emanation of food-borne intoxication. The present study was designed to isolate, identify, and toxinotype C. perfringens from both healthy and cases of necrotic or ulcerative enteritis chickens. A total of 110 samples were collected from July 2019 to February 2021. Among the samples, 38 (34.5%, 95% CI: 26.39-43.83) were positive for C. perfringens and were obtained from broiler 21 (33.3%, 95% CI: 22.91-45.67), Sonali 9 (34.6%, 95% CI: 19.31-53.88), and layer 8 (38%, 95% CI: 20.68-59.20). C. perfringens was highly prevalent (35.7%, 95% CI: 25.48-47.44) in enteritis chickens compared with healthy ones. In multiplex PCR toxinotyping, 34 (89.4%) isolates were identified as C. perfringens type A by the presence of the alpha toxin gene (cpa). Moreover, in addition to the cpa gene, 3 (14.3%, 95% CI: 4.14-35.48) broiler and 1 (11.1%, 95% CI: 0.01-45.67) Sonali isolates harbored the enterotoxin gene (cpe) and were classified as type F. However, none of the isolates carried genes encoding beta (cpb), epsilon (etx), iota (iap), or beta-2 (cpb2) toxins. Multivariable logistic regression analysis identified the following variables such as; "previously used litter materials" (OR 21.77, 95% CI 2.22-212.66, p ≤ 0.008); intestinal lesions, "presence of ulceration" (OR 30.01, 95% CI 3.02-297.91, p ≤ 0.004); "ballooned with gas" (OR 24.74, 95% CI 4.34-140.86, p ≤ 0.001) and "use of probiotics" (OR 5.24, 95% CI 0.74-36.75, p ≤ 0.095) act as risk factors for C. perfringens colonization in chicken gut. This is the first study of molecular toxinotyping of C. perfringens from healthy and enteric-diseased chickens in Bangladesh, which might have a potential food-borne zoonotic impact on human health.

Intermediate role of gut microbiota in vitamin B nutrition and its influences on human health

Vitamin B consists of a group of water-soluble micronutrients that are mainly derived from the daily diet. They serve as cofactors, mediating multiple metabolic pathways in humans. As an integrated part of human health, gut microbiota could produce, consume, and even compete for vitamin B with the host. The interplay between gut microbiota and the host might be a crucial factor affecting the absorbing processes of vitamin B. On the other hand, vitamin B supplementation or deficiency might impact the growth of specific bacteria, resulting in changes in the composition and function of gut microbiota. Together, the interplay between vitamin B and gut microbiota might systemically contribute to human health. In this review, we summarized the interactions between vitamin B and gut microbiota and tried to reveal the underlying mechanism so that we can have a better understanding of its role in human health.

Clostridium perfringens associated with dairy farm systems show diverse genotypes

Clostridium perfringens is a bacterial species of importance to both public and animal health. Frequently found in food system environments, it presents a risk to food animal health such as dairy herds, and may cross contaminate associated ingredients or food products, with potential to cause sporadic and outbreaks of disease in human populations, including gastroenteric illness. In this study, we characterized C. perfringens isolated from bovine, caprine, and ovine dairy farm systems (n = 8, 11 and 4, respectively). Isolates were phenotypically screened for antimicrobial sensitivity profiling, and subjected to whole genome sequencing to elucidate related genetic markers, as well as examine virulence gene markers, mobile genetic elements, and other features. Both toxin type A and type D isolates were identified (78 % and 22 % of isolates, respectively), including 20 novel sequence types. Resistance to clindamycin was most prevalent among antibiotics screened (30 %), followed by erythromycin (13 %), then penicillin and tetracycline (4 %), although an additional 3 isolates were non-susceptible to tetracycline. Most isolates harboured plasmids, which mobilised virulence markers such as etx, cpb2, and resistance markers tetA(P), tetB(P), and erm(Q), on conjugative plasmids. The presence of type D isolates on caprine farms emphasizes the need for control efforts to prevent infection and potential enterotoxemia. Clostridium perfringens enterotoxin (cpe) was not identified, suggesting lower risk of gastrointestinal illness from contaminated foods, the presence of other virulence and antimicrobial resistance markers suggests farm hygiene remains an important consideration to help ensure food safety of associated dairy foods produced.

Influence of dietary lycopene on growth performance, antioxidant status, blood parameters and mortality in broiler chicken with cold-induced ascites

The aim of this study was to determine the effects of dietary lycopene supplementation on growth performance and antioxidant status of broiler chickens exposed to cold environment to induce ascites. Three hundred male chickens were exposed full-day to cold stress (CT, 10°C) starting from day 15 of age until the end of experiment at day 42, while a positive control group (NT, 100 birds) was kept under normal temperature (23-25°C). The CT groups (three treatments and five replicates of 20 birds) were as follows: negative control (basal diet, CT) and CT + 200 or 400 mg lycopene per kg diet from 15 to 42 d of age. Results showed that CT without lycopene supplementation caused a reduction of feed intake and weight gain and increased the feed conversion ratio. Supplementation of lycopene during CT restored the performance to levels of the positive control, lowered the index of right ventricles/total ventricles and ascites mortality. Birds reared under CT had lower serum activities of superoxide dismutase (SOD), glutathione peroxidase (GPx) and higher malondialdehyde (MDA) concentration than birds reared under the NT environment. With lycopene supplementation, serum MDA level significantly decreased and the activity of SOD and GPx increased. Blood concentration of haematocrit, haemoglobin and red blood cells were decreased by the highest lycopene supplementation to a level comparable to NT. Moreover, increasing dietary lycopene level suppressed serum concentrations of cholesterol and enhanced high-density lipoproteins levels in blood. In conclusion, lycopene supplementation alleviates adverse effects of cold stress on performance through modulating activity of antioxidant enzymes in broiler chickens.

Severe gastroenteropathy associated with Clostridium perfringens isolation in starving juvenile sturgeons

In November 2020 a mortality episode (30%) in juvenile Siberian and Russian sturgeons (Acipenser baerii, Brandt, and A. gueldenstaedtii, Brandt & Ratzeburg) and GUBA hybrid sturgeons (A. gueldenstaedtii × A. baerii) occurred in a hatchery in Northern Italy, associated with severe coelomic distension and abnormal reverse surface swimming. The fish were reared in concrete tanks supplied by well water, fed at 0.4% of body weight (b.w.) per day. Thirty sturgeon specimens were collected for necropsy, histological, bacteriological and virological examination. Macroscopic findings included diffuse and severe bloating of gastrointestinal tracts due to foamy contents with thinning and stretching of the gastrointestinal walls. Histological analysis revealed variable degrees of sloughing and necrosis of the intestinal epithelium, and the presence of bacterial aggregates. Anaerobic Gram-positive bacteria were investigated, and Clostridium perfringens was isolated from the gut. Specific PCRs identified the toxinotype A and the β2 toxin gene. The daily feed administration was increased to 1.5% b.w. and after 5 days, the mortality ceased. A new animal cohort from the same groups was examined after 12 weeks, showing neither gut alterations nor isolation of C. perfringens. The imbalance of intestinal microbiota, presumably caused by underfeeding, favoured C. perfringens overgrowth and severe gas formation. The diet increase possibly restored the normal microbiota.

Influence of Feeding Compound Feed Rich in Fibre during Parturition and Lactation on Health and Performance of Sows

Simple Summary

Although it is known that restriction of feed negatively influences the behaviour and welfare of sows, it is widely adopted during the gestation period to counteract nutrient oversupply. Nonetheless, a healthy gut needs its fuel and is a prerequisite for preventing birth-associated health disorders. Including high amounts of fibre in diets around parturition could be the solution for behavioural disorders and health problems in sows and therefore in piglets as well. The purpose of this study was to investigate the influence of ad libitum access to compound feeds rich in fibre (ante partum and peri partum) and a lactation diet (post partum) on the performance and health of sows. This study indicated that a higher feed intake of a fibre-rich diet ante partum did not interfere with any birth-associated disorders. In addition, ad libitum-fed sows showed higher dry matter (DM) intake throughout lactation, which led to beneficial effects on the body condition scores of sows. Due to the high fibre intake, the excretion of C. perfringens via sows’ faeces could be significantly reduced, which could be a helpful tool in reducing the risk of neonatal diarrhoea caused by C. perfringens.

Abstract

The aim of this study was to investigate the influence of ad libitum access to compound feeds rich in fibre (ante partum (a.p.) and peri partum) on the DM intake, body mass development and performance of sows as well as excretion of Clostridium (C.) perfringens via sows’ faeces. From day 109 (d-7) of gestation, 25 of 48 sows (23 considered as control) received access to one of two different high-fibre pellets from d-7 until the second day post partum (p.p.) (d2) (fibre groups (FG) 1 and 2) in additional to a lactation diet. The additional DM intake of the high-fibre pellets a.p. was 2.13 ± 1.15 kg in FG 1 and 3.14 ± 0.68 kg in FG 2. This led to higher DM intake in the first lactation week and significantly lower losses of weight and back fat thickness during lactation. The bacterial counts of C. perfringens in sows’ faeces directly p.p. were 10 times lower in FG 1 and 100 times lower in FG 2 compared to the controls. High amounts of fibre led to higher DM intake throughout lactation, which had beneficial effects on sows’ body conditions. It seems that high fibre intake influenced the excretion of C. perfringens at parturition, which could improve the health of newborns.

Dietary supplementation of essential oils and lysozyme reduces mortality and improves intestinal integrity of broiler chickens with necrotic enteritis

The objective of this study was to investigate the individual and combined effects of essential oils (EO; comprised of thymol and carvacrol) and lysozyme on experimental NE in broiler chickens. A total of 320 1-day-old chicks were randomly assigned to five treatment groups: no-challenge control (NC), NC + C. perfringens challenge (CC), CC + 120 mg/kg of EO, CC + 100 mg/kg of lysozyme, and CC + 120 mg/kg of EO + 100 mg/kg of lysozyme. The results showed that EO or lysozyme decreased the mortality, alleviated the gut lesions, inhibited the liver Enterobacteriaceae carriage, and increased the villus height of the ileum compared with CC (p < .05), although the proliferation of C. perfringens in the ileum was not inhibited (p > .05). Moreover, EO or lysozyme was found to decrease the ileal concentration of sialic acid and the Mucin2 mRNA expression (p < .05). However, the blend of EO and lysozyme did not display significant effect on the NE-associated mortality or gut damage in contrast with CC (p > .05). In conclusion, these findings suggest the similar protective effects of EO and lysozyme in NE-associated mortality and intestinal impairment, but their blend did not exhibit ameliorative effect.

Mandated restrictions on the use of medically important antibiotics in broiler chicken production in Canada: implications, emerging challenges, and opportunities for bolstering gastrointestinal function and health– A review

Chicken Farmers of Canada has been progressively phasing out prophylactic use of antibiotics in broiler chicken production. Consequently, hatcheries, veterinarians, and nutritionists have been mandated to contend with less reliance on use of preventive antibiotics. A topical concern is the increased risk of proliferation of enteric pathogens leading to poor performance, increased mortality and compromised welfare. Moreover, the gut harbors several taxa such as Campylobacter and Salmonella capable of causing significant illnesses in humans via contaminated poultry products. This has created opportunity for research and development of dietary strategies designed to modulate gastrointestinal environment for enhanced performance and food safety. Albeit with inconsistent responses, literature data suggests that dietary strategies such as feed enzymes, probiotics/prebiotics and phytogenic feed additives can bolster gut health and function in broiler chickens. However, much of the efficacy data was generated at controlled research settings that vary significantly with the complex commercial broiler production operations due to variation in dietary, health and environmental conditions. This review will summarize implications of mandated restrictions on the preventative use of antibiotics and emerging Canadian broiler production programs to meet processor specifications. Challenges and opportunities for integrating alternative dietary strategies in commercial broiler production settings will be highlighted.

A Sarcina bacterium linked to lethal disease in sanctuary chimpanzees in Sierra Leone

Human and animal infections with bacteria of the genus Sarcina (family Clostridiaceae) are associated with gastric dilation and emphysematous gastritis. However, the potential roles of sarcinae as commensals or pathogens remain unclear. Here, we investigate a lethal disease of unknown etiology that affects sanctuary chimpanzees (Pan troglodytes verus) in Sierra Leone. The disease, which we have named "epizootic neurologic and gastroenteric syndrome" (ENGS), is characterized by neurologic and gastrointestinal signs and results in death of the animals, even after medical treatment. Using a case-control study design, we show that ENGS is strongly associated with Sarcina infection. The microorganism is distinct from Sarcina ventriculi and other known members of its genus, based on bacterial morphology and growth characteristics. Whole-genome sequencing confirms this distinction and reveals the presence of genetic features that may account for the unusual virulence of the bacterium. Therefore, we propose that this organism be considered the representative of a new species, named "Candidatus Sarcina troglodytae". Our results suggest that a heretofore unrecognized complex of related sarcinae likely exists, some of which may be highly virulent. However, the potential role of "Ca. S. troglodytae" in the etiology of ENGS, alone or in combination with other factors, remains a topic for future research.

Avian Pathogenic Escherichia coli and Clostridium perfringens: Challenges in No Antibiotics Ever Broiler Production and Potential Solutions

United States is the largest producer and the second largest exporter of broiler meat in the world. In the US, broiler production is largely converting to antibiotic-free programs which has caused an increase in morbidity and mortality within broiler farms. Escherichia coli and Clostridium perfringens are two important pathogenic bacteria readily found in the broiler environment and result in annual billion-dollar losses from colibacillosis, gangrenous dermatitis, and necrotic enteritis. The broiler industry is in search of non-antibiotic alternatives including novel vaccines, prebiotics, probiotics, and housing management strategies to mitigate production losses due to these diseases. This review provides an overview of the broiler industry and antibiotic free production, current challenges, and emerging research on antibiotic alternatives to reduce pathogenic microbial presence and improve bird health.

Refined functional carbohydrates reduce adhesion of Salmonella and Campylobacter to poultry epithelial cells in vitro

The development of interventions to reduce human foodborne pathogens in the gastrointestinal (GI) tract of chickens will be important for improving the microbial food safety of poultry. Saccharomyces-derived prebiotic refined functional carbohydrates (RFC), composed primarily of β-glucans, mannanoligosaccharides (MOS), and D-mannose have been demonstrated to reduce GI colonization of Salmonella and Campylobacter when administered to poultry. Although they are presumed to inhibit adhesion of pathogens to the GI epithelium, this functionality of RFC has not been well characterized. In this study, we investigated the effects of RFC and other prebiotics on the adhesion of Salmonella Typhimurium and Campylobacter jejuni to the LMH chicken epithelial cell line in vitro. The reduction of adherent pathogens was observed to be dose-dependent with C. jejuni being more sensitive than Salmonella to inhibition by RFC. Comparison of the primary constituent carbohydrates of RFC found D-mannose to inhibit both pathogens less effectively than β-glucan and MOS, suggesting that it contributes less to inhibition of pathogen adhesion than the other carbohydrates. Finally, the reduction of adherent pathogens by RFC was compared with that of fructooligosaccharides (FOS), galactooligosaccharides (GOS), and raffinose. All 4 prebiotics inhibited adhesion of both pathogens to chicken epithelial cells. Reduction of adherent Salmonella was greatest with FOS and lowest with GOS, whereas reduction of adherent C. jejuni was greater with RFC and raffinose than with FOS and GOS. These results will inform future research elucidating mechanisms important to adhesion inhibition of pathogens by RFC and other prebiotics.

Administration of dietary prebiotics improves growth performance and reduces pathogen colonization in broiler chickens

Dietary prebiotics are thought to be potentially important alternatives to antibiotic growth promoters in poultry production because of their beneficial performance and health effects. The administration of dietary prebiotics has been demonstrated to improve animal health, growth performance, and microbial food safety in poultry production. In this study, we evaluated the effects of Saccharomyces- derived prebiotic refined functional carbohydrates (RFC) with yeast culture on growth performance and gastrointestinal and environmental microbiota when administered in-feed and through drinking water to broiler chickens. Broilers were administered 2 doses of prebiotic in-feed through 42 d of production and prebiotic-treated water in the final 72 h. Administration of prebiotic RFC improved ADG and decreased cecal Campylobacter counts, while the high dose also increased final BW. Additionally, significant main effects of prebiotic RFC dose were observed with the high dose improving ADG and ADFI over the finisher phase and final BW. Although the effects were not significant, the prevalence of Campylobacter in the cecum after feed withdrawal was 17% lower when broilers were administered the high prebiotic dose, and recovery of Campylobacter from litter was up to 50% lower when broilers were administered prebiotic RFC. Our results suggest that co-administration of RFC with yeast culture as a prebiotic can be used to improve growth performance and reduce human foodborne pathogens in poultry.

The Effect of Clostridium butyricum on Gut Microbiota, Immune Response and Intestinal Barrier Function During the Development of Necrotic Enteritis in Chickens

Necrotic enteritis (NE) causes huge economic losses to the poultry industry. Probiotics are used as potential alternatives to antibiotics to prevent NE. It is known that Clostridium butyricum can act as a probiotic that can prevent infection. However, whether or not it exerts a beneficial effect on NE in chickens remains elusive. Therefore, we investigated the impact of C. butyricum on immune response and intestinal microbiota during the development of NE in chickens, including experimental stages with basal diets, high-fishmeal-supplementation diets, and Clostridium perfringens challenge. Chickens were divided into two groups from day 1 to day 20: one group had its diet supplemented with C. butyricum supplementation and one did not. At day 20, the chickens were divided into four groups: C. perfringens challenged and unchallenged chickens with and without C. butyricum supplementation. All groups were fed a basal diet for 13 days and thereafter a basal diet with 50% fishmeal from day 14 to 24. Chickens were infected with C. perfringens from day 21 to 23. At days 13, 20 and 24, samples were collected for analysis of the relative expression of immune response and intestinal mucosa barrier-related genes and intestinal microbes. The results show that C. butyricum can inhibit the increase in IL-17A gene expression and the reduction in Claudin-1 gene induced-expression caused by C. perfringens challenge. Moreover, C. butyricum was found to increase the expression of anti-inflammatory IL-10 in infected chickens. Although C. butyricum was found to have a significant beneficial effect on the structure of intestinal bacteria in the basal diet groups and decrease the abundance of C. perfringens in the gut, it did not significantly affect the occurrence of intestinal lesions and did not significantly correct the shift in gut bacterial composition post C. perfringens infection. In conclusion, although C. butyricum promotes the expression of anti-inflammatory and tight junction protein genes and inhibits pro-inflammatory genes in C. perfringens-challenged chickens, it is not adequate to improve the structure of intestinal microbiota in NE chickens. Therefore, more effective schemes of C. butyricum supplementation to prevent and treat NE in chickens need to be identified.

Profiling of Egg Layer Flocks Affected with Focal Duodenal Necrosis Based on a Questionnaire Survey

Focal duodenal necrosis (FDN) is an intestinal disease of egg-laying chickens, characterized by multifocal mucosal erosions in the duodenal loop and proximal jejunum. It is currently considered by the Association of Veterinarians in Egg Production and the United States Animal Health Association as one of the top five disease concerns of the table egg industry in the United States. Previous studies have associated this condition with Clostridium species. The purpose of this study was to investigate the epidemiologic characteristics of table egg layer flocks affected with FDN. An online questionnaire was distributed to commercial layer operations in different states in the United States. Layer farms that had diagnosed FDN within the past 12 mo were surveyed. The questionnaire had 45 questions about management, nutrition, housing, and methods for disease prevention and control. Thirty-seven surveys were sent and 21 were completed, which represents a response rate of 56.7%. The survey results showed the presence of FDN in five egg-layer genetic lines or breed crosses of different ages, with most cases reported between 30-39 wk of age. The pullets were cage-reared in all affected flocks and the majority of flocks in production were housed in traditional cages. Most of the FDN-affected flocks received more than 12 different feed formulations from pre-lay to 60 wk of age. Distiller's dried grain with solubles was a common ingredient added to the feed in the majority of affected flocks, and all flocks were provided with limestone as a calcium source for egg production. Most surveys reported that coccidiosis and roundworm parasitism were not problems in affected flocks in production; however, pests such as flies and rodents were reported as problems in most affected flocks. Additionally, most affected farms never washed feeders, cages, and houses before disinfection, which may not be sufficient to prevent the persistency and transmission of the causative agent of FDN. In conclusion, several management practices that have been associated with enteric disease, including clostridial-associated enteritis, were described by the majority of FDN-affected flocks. Additional studies are needed to determine if management and health practices identified in this survey represent risk factors for FDN.

An optimist's view on limiting necrotic enteritis and maintaining broiler gut health and performance in today's marketing, food safety, and regulatory climate

The future poultry nutritionist, veterinarian, and husbandryman will have many new regulatory requirements and consumer preferences to navigate in addition to their normal responsibility of raising birds in a cost-efficient and wholesome manner. New challenges include changes to antibiotic use, increased food safety regulations, and more concern over how birds are raised and how to dispose of poultry house waste. All of these new programs and new regulations will alter how we have been raising birds for the last 60 years since the inception of the integrated poultry industry. The most significant change may be the voluntary or regulatory withdrawal of the use of antibiotics in poultry production. In North America, this withdrawal of antibiotic use includes removal of in-ovo antibiotics, performance-improving antibiotics or antibiotic growth promotors (AGP), and the polyether ionophore antibiotics (ionophore anticoccidials).The removal of antibiotics in poultry production may result in welfare concerns due to elevated mortality and less efficient feed conversion, resulting in greater environmental impacts from increased manure production and more use of grain per unit of meat produced. There also may be concerns with greater intestinal disease in the birds resulting in increased numbers of foodborne illness-causing bacteria such as Salmonella sp. or Campylobacter sp. on the carcass. A major impact will be the disease necrotic enteritis (NE). This review will focus on the pathophysiology of NE, the management of the disease, and the additional effects on growth rate, feed efficiency, and body weight that may be associated with NE.

Dietary soy, meat, and fish proteins modulate the effects of prebiotic raffinose on composition and fermentation of gut microbiota in rats

Soy, meat (mixture of pork and beef), and fish proteins were fed to rats with and without prebiotic raffinose (RAF), and the composition and fermentation of gut microbiota were examined. Bifidobacterium spp. populations were higher, and propionic acid concentration was lower in soy protein-fed than meat protein-fed rats. Likewise, Enterobacteriaceae populations were higher in fish protein-fed rats than other rats. RAF feeding increased Bifidobacterium spp. and decreased Faecalibacterium prausnitzii populations regardless of the dietary protein source. Interactions between dietary proteins and RAF were shown for Lactobacillus spp. and Clostridium perfringens group; the increase of Lactobacillus spp. populations by RAF was seen only for soy protein-fed rats, whereas the reduction of C. perfringens group by RAF was evident in fish and meat protein-fed rats. It is concluded that dietary proteins may differentially modulate the effects of prebiotic oligosaccharides on gut fermentation and microbiota, with differences observed between plant and animal proteins.

Impact of Controlling Bacteria in Feed on Broiler Performance During a Clostridial Challenge

Three studies were conducted using Clostridium perfringens as an intestinal challenge to produce necrotic enteritis (NE). The studies consisted of two battery screening studies and one production study in floor pens. The purpose of the trials was to determine if reducing the level of microorganisms in feed consumed by broilers reduced the impact of a nonfeed-based Clostridial challenge. In all studies, C. perfringens challenged broilers consuming feed containing lower levels of microorganisms compared to control feed exhibited significantly ( P < 0.05) better feed conversion (feed conversion was improved by 14% in battery trials and by 4.2% in the pen trial) than did C. perfringens-challenged broilers consuming control feed. In battery trials, body weight gain and NE-associated mortality were also significantly improved in C. perfringens-challenged broilers consuming feed containing lower levels of microorganisms (16.5% improvement in body weight gain and 72.5% reduction in NE-associated mortality). In the pen trial, body weight gain and NE-associated mortality appeared unaffected by feed microbial quality. No effect was observed on lesion scores. The present data indicate that reducing the level of microorganisms in feed can ameliorate some of the performance losses associated with a Clostridia challenge.

Microbial shifts associated with necrotic enteritis

An outbreak of necrotic enteritis (NE) is a complex process requiring one or a number of predisposing factors rather than just the presence of pathogenic Clostridium perfringens. Examples are dietary influences, such as high levels of non-starch polysaccharides and fishmeal, and factors that evoke epithelial cell damage, such as Fusarium mycotoxins in feed and Eimeria infections. Recent studies have shown that different predisposing factors induce similar shifts in the intestinal microbiota composition. Butyrate-producing-strains of the Ruminococcaceae family are decreased in abundance by both fishmeal and Eimeria. Similarly, a decreased abundance of butyrate-producing-strains belonging to the Lachnospiraceae family has been induced by fishmeal. Also shifts are observed in the lactic acid-producing bacteria, such as decreased abundance of Lactobacillus johnsonii or Weissella confusa, when broilers were fed a fishmeal-based diet or a Fusarium mycotoxin contaminated diet. Finally, the abundance of Candidatus Savagella was decreased in broilers following Eimeria challenge or feeding a fumonisins contaminated diet. The nature of the microbiota shifts indicate that immune modulatory actions of the intestinal microbiota may play a critical role in the effect on the necrosis inducing activity of C. perfringens. Indeed, colonization with butyrate-producing bacteria plays a key role in counteracting inflammation in the gut and preserving intestinal integrity, while Candidatus Savagella is involved in stimulating Th17 and immunoglobulin A responses. Lactic acid bacteria stimulate colonization of lactate-utilizing and butyrate-producing Lachnospiraceae. Future research needs to clarify the role of the microbiota changes in the pathogenesis of NE.

Necrotic enteritis predisposing factors in broiler chickens

Necrotic enteritis in chickens develops as a result of infection with pathogenic strains of Clostridium perfringens and the presence of predisposing factors. Predisposing factors include elements that directly change the physical properties of the gut, either damaging the epithelial surface, inducing mucus production, or changing gut transit times; factors that disrupt the gut microbiota; and factors that alter the immune status of birds. In the past research into necrotic enteritis predisposing factors was directed by the simple hypothesis that low-level colonization of C. perfringens commonly occurred within the gut of healthy chickens and the predisposing factors lead to a proliferation of those bacteria to produce disease. More recently, with an increasing understanding of the major virulence factors of C. perfringens and the application of molecular techniques to define different clades of C. perfringens strains, it has become clear that the C. perfringens isolates commonly found in healthy chickens are generally not strains that have the potential to cause disease. Therefore, we need to re-evaluate hypotheses regarding the development of disease, the origin of disease causing isolates of C. perfringens, and the importance of interactions with other C. perfringens strains and with predisposing factors. Many predisposing factors that affect the physical and immunological characteristics of the gastrointestinal tract may also change the resident microbiota. Research directed towards defining the relative importance of each of these different actions of predisposing factors will improve the understanding of disease pathogenesis and may allow refinement of experiment disease models.

Review of transmission routes of 24 infectious diseases preventable by biosecurity measures and comparison of the implementation of these measures in pig herds in six European countries

This study aimed to review the transmission routes of important infectious pig diseases and to translate these into biosecurity measures preventing or reducing the transmission between and within pig herds. Furthermore, it aimed to identify the level of implementation of these measures in different European countries and discuss the observed variations to identify potentials for improvement. First, a literature review was performed to show which direct and indirect transmission routes of 24 infectious pig diseases can be prevented through different biosecurity measures. Second, a quantitative analysis was performed using the Biocheck.UGent™, a risk-based scoring system to evaluate biosecurity in pig herds, to obtain an insight into the implementation of these biosecurity measures. The database contained farm-specific biosecurity data from 574 pig farms in Belgium, Denmark, France, Germany, the Netherlands and Sweden, entered between January 2014 and January 2016. Third, a qualitative analysis based on a review of literature and other relevant information resources was performed for every subcategory of internal and external biosecurity in the Biocheck.UGent™ questionnaire. The quantitative analysis indicated that at the level of internal, external and overall biosecurity, Denmark had a significantly distinct profile with higher external biosecurity scores and less variation than the rest of the countries. This is likely due to a widely used specific pathogen-free (SPF) system with extensive focus on biosecurity since 1971 in Denmark. However, the observed pattern may also be attributed to differences in data collection methods. The qualitative analysis identified differences in applied policies, legislation, disease status, pig farm density, farming culture and habits between countries that can be used for shaping country-specific biosecurity advice to attain improved prevention and control of important pig diseases in European pig farms.

Disruption in the cecal microbiota of chickens challenged with Clostridium perfringens and other factors was alleviated by Bacillus licheniformis supplementation

Clostridium perfringens can induce necrotic enteritis of chickens, which causes large economic losses every year. Bacillus licheniformis, a probiotic, can inhibit the growth of pathogenic bacteria such as Clostridium perfringens, thereby improving the health status of chickens. However, from a microbial ecology perspective, the mechanisms by which alterations to the gut microbiota improve health remain unknown. In this study, we used Illumina MiSeq sequencing to investigate the cecal microbiota of a negative control group (NC), a C. perfringens and Eimeria challenge group with fishmeal supplementation (PC), a group supplemented with fishmeal and infected with coccidia (FC), and group PC with B. licheniformis supplementation (BL). We found that the health status of C. perfringens-challenged chickens was compromised, and that B. licheniformis improved the growth of the chickens challenged with pathogens. Microbial diversity analysis and taxonomic profiling of groups NC, PC, and FC revealed a disturbed cecal microflora of the birds with C. perfringens. We also characterized the microbiota of the chickens in the BL group using several methods. Principal coordinate analysis demonstrated that, compared with group PC, the bacterial community structure of group BL was more similar to that of group NC. Linear discriminant analysis with effect size revealed less differentially represented bacterial taxa between groups BL and NC than between groups PC and NC. In addition, groups BL and NC appeared to have similar overrepresented microbial taxa (such as Bacteroides, Helicobacter, Megamonas, and Akkermansia) compared with group PC. Finally, a phylogenetic investigation of communities by reconstruction of unobserved states analysis indicated that large differences existed between group PC and groups NC and BL. In conclusion, pre-treatment with B. licheniformis reduced the disturbance of the cecal microbiome induced by challenge with C. perfringens and other factors in broiler chickens.

Rethinking the role of alpha toxin in Clostridium perfringens-associated enteric diseases: a review on bovine necro-haemorrhagic enteritis

Bovine necro-haemorrhagic enteritis is an economically important disease caused by Clostridium perfringens type A strains. The disease mainly affects calves under intensive rearing conditions and is characterized by sudden death associated with small intestinal haemorrhage, necrosis and mucosal neutrophil infiltration. The common assumption that, when causing intestinal disease, C. perfringens relies upon specific, plasmid-encoded toxins, was recently challenged by the finding that alpha toxin, which is produced by all C. perfringens strains, is essential for necro-haemorrhagic enteritis. In addition to alpha toxin, other C. perfringens toxins and/or enzymes might contribute to the pathogenesis of necro-haemorrhagic enteritis. These additional virulence factors might contribute to breakdown of the protective mucus layer during initial stage of pathogenesis, after which alpha toxin, either or not in synergy with other toxins such as perfringolysin O, can act on the mucosal tissue. Furthermore, alpha toxin alone does not cause intestinal necrosis, indicating that other virulence factors might be needed to cause the extensive tissue necrosis observed in necro-haemorrhagic enteritis. This review summarizes recent research that has increased our understanding of the pathogenesis of bovine necro-haemorrhagic enteritis and provides information that is indispensable for the development of novel control strategies, including vaccines.

Prevalence and factors associated with the occurrence of bacterial enteropathogens in suckling piglets in farrow-to-finish herds

The aim of the study was to determine both environmental and infectious factors, influencing occurrence of bacterial enteropathogens in suckling piglets. For this purpose, a cross-sectional study in 70 Polish farrow-to-finish pig herds was performed. In each herd, presence of selected intestinal pathogens (Escherichia coli, Clostridium perfringens and Salmonella species) in faeces of suckling piglets were determined using bacteriological and PCR methods. Using logistic regression models, risk factors for enterotoxigenic E coli with fimbriae F4 (ETEC-F4) and C perfringens type A were established. Prevalence of bacterial enteropathogens in investigated herds was as follows (on herd and sample level): ETEC-F4 30.0 per cent and 9.3 per cent, respectively, C perfringens type A 91.4 per cent and 58.3 per cent, C perfringens type C 1.4 per cent and 0.3 per cent, Salmonella species 2.9 per cent and 0.5 per cent. The occurrence of ETEC-F4 was associated with presence of diarrhoea in piglets and vulval discharge in sows. Vulval discharge in sows, not slatted floor in farrowing pen and lack of coccidiosis prevention were determined as risk factors for C perfringens type A. The results obtained in the study revealed the high prevalence of enteropathogenic bacteria in pig herds and indicate management and organisation of production as factors having the greatest impact on the incidence of bacterial enteropathogens in piglets before weaning.

Dietary Casein and Soy Protein Isolate Modulate the Effects of Raffinose and Fructooligosaccharides on the Composition and Fermentation of Gut Microbiota in Rats

Although diet has an important influence on the composition of gut microbiota, the impact of dietary protein sources has only been studied to a minor extent. In this study, we examined the influence of different dietary protein sources regarding the effects of prebiotic oligosaccharides on the composition and metabolic activity of gut microbiota. Thirty female rats were fed casein and soy protein isolate with cellulose, raffinose (RAF), and fructooligosaccharides (FOS). Microbiota composition was examined by real-time qPCR and denaturing gradient gel electrophoresis. Dietary protein source affected cecum microbiota; acetic acid concentration and Lactobacillus spp. populations were greater with soy protein than with casein. Prebiotic oligosaccharides had distinctive effects on gut microbiota; RAF increased the acetic acid concentration and Bifidobacterium spp. populations, and FOS increased the butyric acid concentration regardless of the dietary protein. Likewise, Bifidobacterium sp., Collinsella sp., and Lactobacillus sp. were detected in microbiota of the rats fed RAF, and Bacteroides sp., Roseburia sp., and Blautia sp. were seen in microbiota of the rats fed FOS. Interactions between dietary proteins and prebiotic oligosaccharides were observed with Clostridium perfringens group populations and cecum IgA concentration. RAF and FOS decreased C. perfringens group populations in casein-fed rats, and the combination of soy protein and RAF substantially increased cecum IgA concentration. These results indicate that dietary proteins can differentially modulate the effects of prebiotic oligosaccharides on gut fermentation and microbiota, depending on the type of carbohydrate polymers involved.

Lactic acid bacteria as protective cultures in fermented pork meat to prevent Clostridium spp. growth

In meat fermented foods, Clostridium spp. growth is kept under control by the addition of nitrite. The growing request of consumers for safer products has led to consider alternative bio-based approaches, the use of protective cultures being one of them. This work is aimed at checking the possibility of using two Lactobacillus spp. strains as protective cultures against Clostridium spp. in pork ground meat for fermented salami preparation. Both Lactobacillus strains displayed anti-clostridia activity in vitro using the spot agar test and after co-culturing them in liquid medium with each Clostridium strain. Only one of them, however, namely L. plantarum PCS20, was capable of effectively surviving in ground meat and of performing anti-microbial activity in carnis in a challenge test where meat was inoculated with the Clostridium strain. Therefore, this work pointed out that protective cultures can be a feasible approach for nitrite reduction in fermented meat products.

The Exosporium Layer of Bacterial Spores: a Connection to the Environment and the Infected Host

Much of what we know regarding bacterial spore structure and function has been learned from studies of the genetically well-characterized bacterium Bacillus subtilis. Molecular aspects of spore structure, assembly, and function are well defined. However, certain bacteria produce spores with an outer spore layer, the exosporium, which is not present on B. subtilis spores. Our understanding of the composition and biological functions of the exosporium layer is much more limited than that of other aspects of the spore. Because the bacterial spore surface is important for the spore's interactions with the environment, as well as being the site of interaction of the spore with the host's innate immune system in the case of spore-forming bacterial pathogens, the exosporium is worthy of continued investigation. Recent exosporium studies have focused largely on members of the Bacillus cereus family, principally Bacillus anthracis and Bacillus cereus. Our understanding of the composition of the exosporium, the pathway of its assembly, and its role in spore biology is now coming into sharper focus. This review expands on a 2007 review of spore surface layers which provided an excellent conceptual framework of exosporium structure and function (A. O. Henriques and C. P. Moran, Jr., Annu Rev Microbiol 61:555-588, 2007, http://dx.doi.org/10.1146/annurev.micro.61.080706.093224). That review began a process of considering outer spore layers as an integrated, multilayered structure rather than simply regarding the outer spore components as independent parts.

Effects of thymol and carvacrol supplementation on intestinal integrity and immune responses of broiler chickens challenged with Clostridium perfringens

BACKGROUND

Necrotic enteritis caused by Clostridium perfringens infection leads to serious economic losses in the global poultry production. In the present study, we investigated the protective effects of essential oils (EO, which contained 25 % thymol and 25 % carvacrol as active components) supplementation on growth performance, gut lesions, intestinal morphology, and immune responses of the broiler chickens infected with C. perfringens. A total of 448 1-day-old male broiler chicks were allocated into eight treatment groups following a 4 × 2 factorial arrangement with four dietary EO dosages (0, 60, 120, or 240 mg/kg) and two infection status (with or without C. perfringens challenge from d 14 to 20).

RESULTS

The challenge did not impair the growth performance of birds, but induced gut lesions and increased crypt depth in the ileum (P ≤ 0.05). It also down-regulated the claudin-1 and occludin mRNA expression (P ≤ 0.05), up-regulated the mRNA expression of interleukin-1β (P ≤ 0.05), tended to increase the toll-like receptor (TLR) 2 mRNA expression (P < 0.10) in the ileum, and enhanced the mucosal secretory IgA production (P ≤ 0.05). In the challenged birds, dietary EO supplementation linearly alleviated the gut lesions and improved the ratio of villus height to crypt depth (P ≤ 0.05), and the supplementation of 120 and 240 mg/kg EO increased the serum antibody titers against Newcastle disease virus (P ≤ 0.05). Regardless of challenge, the EO supplementation showed a tendency to linearly elevate the feed conversion efficiency between 14 and 28 d of age as well as the occludin mRNA expression (P < 0.10), and linearly inhibited the mRNA expression of TLR2 and tumor necrotic factor-α in the ileum (P ≤ 0.05).

CONCLUSIONS

The dietary supplementation of EO could alleviate the intestinal injury by improving intestinal integrity and modulating immune responses in the C. perfringens-challenged broiler chickens.

Impact of a drug-free program on broiler chicken growth performances, gut health, Clostridium perfringens and Campylobacter jejuni occurrences at the farm level

The use of antimicrobial agents as feed additives in poultry production is a public health concern due to the overall increase in antimicrobial resistance. Although some alternative products are commercially available, little is known on their potential impact on flock health and productivity. A prospective study involving 1.55 million birds was conducted on eight commercial broiler farms in Québec, Canada, to evaluate the impact of replacing antibiotic growth promoters and anticoccidial drugs by a drug-free program including improved brooding conditions, anticoccidial vaccination, essential oil-based feed additives, and water acidification. Various productivity and health parameters were compared between barns allocated to the conventional and the drug-free program. Zootechnical performances were monitored as productivity criteria. Clinical necrotic enteritis and subclinical enteritis occurrences, litter and fecal moistures content were measured, and microscopic gut health was evaluated. Clostridium perfringens and Campylobacter spp. strains were recovered from fecal samples collected during farm visits. Clostridium perfringens counts were used as poultry health indicators and Campylobacter prevalence was noted as well. The drug-free program was associated with a significant increase in feed conversion ratio and a decrease in mean live weight at slaughter and in daily weight gain. An increased incidence of necrotic enteritis outbreaks and subclinical enteritis cases, as well as an increase in litter moisture content at the end of the rearing period were also observed for this program. Mean microscopic intestinal lesion scores and prevalence of Campylobacter colonization were not statistically different between the two groups but the drug-free program was associated with higher Clostridium perfringens isolation rates. According to the current study design, the results suggest that substitution of antibiotic growth promoters and anticoccidial drugs by a drug-free program impacts various broiler chicken production parameters and Clostridium perfringens carriage levels.