Contamination Sources and Transmission Routes for Campylobacter on (Mixed) Broiler Farms in Belgium, and Comparison of the Gut Microbiota of Flocks Colonized and Uncolonized with Campylobacter

Role of Maternal Antibodies in the Protection of Broiler Chicks against Campylobacter Colonization in the First Weeks of Life

Thermophilic Campylobacter species are the most common cause of bacterium-mediated diarrheal disease in humans globally. Poultry is considered the most important reservoir of human campylobacteriosis, but so far, no effective countermeasures are in place to prevent the bacterium from colonizing broiler flocks. This study investigated maternal antibodies' potential to offer protection against Campylobacter in broiler chicks via a field trial and an immunization trial. In the field trial, breeder flocks with high and low anti-Campylobacter antibody levels in the yolk were selected based on serological screening. Offspring were subsequently monitored for maternal antibodies and Campylobacter prevalence during early life. Although maternal antibodies declined rapidly in the serum of broilers, offspring from flocks with lower anti-Campylobacter antibody levels seemed to be more susceptible to colonization. In the immunization trial, breeders from a seropositive breeder flock were vaccinated with an experimental bacterin or subunit vaccine. Immunization increased antibody levels in the yolk and consequently in the offspring. Elevated maternal antibody levels were significantly associated with reduced Campylobacter susceptibility in broilers at 2 weeks old but not at 1 and 3 weeks old. Overall, the protective effect of maternal immunity should be cautiously considered in the context of Campylobacter control in broilers. Immunization of breeders may enhance resistance but is not a comprehensive solution.

Stakeholders' Perceptions of Biosecurity Implementation in Italian Poultry Farms

The level of implementation of biosecurity measures (BMs), the reasons for not implementing BMs and the effectiveness of BMs were assessed according to the perceptions of stakeholders (i.e., farmers and advisors) in Italian poultry farms. For this purpose, data were collected using a questionnaire administered to advisors (n = 37) and farmers (n = 30) of conventional broiler (n = 13) and layer (n = 13), free-range broiler (n = 8) and layer (n = 10), turkey (n = 13), duck (n = 3) and breeder (n = 7) farms between April and September 2021. The frequency of the implementation of BMs was 66.97% and 81.14% according to the answers provided by the advisors and farmers, respectively, with the breeder sector showing the highest level of implementation (85.71%). "Not knowing advantages" (21.49% for advisors) and "other/specific reasons" (21.49% for advisors and 38.32% for farmers) were the most common answers regarding the lack of implementation of BMs for all poultry sectors. Only 31.09% of farmers acknowledged the effectiveness of not-implemented BMs in contrast to 61.02% of advisors, with the layers' stakeholders being the most aware. The findings of this study may be useful for identifying failures in biosecurity and failures to develop intervention strategies to fulfil the biosecurity gaps still present in Italian poultry farms.

Detection of Viable but Non-Culturable (VBNC)-Campylobacter in the Environment of Broiler Farms: Innovative Insights Delivered by Propidium Monoazide (PMA)-v-qPCR Analysis

Campylobacteriosis cases in humans are of global concern, with high prevalence rates in the poultry reservoir considered the most important source of infection. Research findings show Campylobacters' ability to enter a viable but non-culturable (VBNC) state, remaining "viable" but unable to grow on culture media. We explored the persistence of VBNC states in specific environments, particularly at broiler farms, as this state may lead to an underestimation of the present Campylobacter prevalence. For VBNC detection, a propidium monoazide PMA-dye viability qPCR (v-qPCR) was used in combination with cultivation methods. We examined samples collected from broiler farm barns and their surroundings, as well as chicken manure from experimental pens. In addition, the tenacity of culturable and VBNC-Campylobacter was studied in vitro in soil and water. In a total of three visits, Campylobacter was not detected either culturally or by v-qPCR (no Campylobacter DNA) in the environment of the broiler farms. In four visits, however, VBNC-Campylobacter were detected both inside and outside the barns. The overall prevalence in environmental samples was 15.9% for VBNC-Campylobacter, 62.2% for Campylobacter DNA, and 1.2% for culturable C. jejuni. In the experimental pens, no cultivable C. jejuni was detected in chicken manure after 24 h. Strikingly, "VBNC-Campylobacter" persisted even after 72 h. "VBNC-Campylobacter" were confirmed in barn surroundings and naturally contaminated chicken manure. Laboratory studies revealed that VBNC-Campylobacter can remain intact in soil for up to 28 days and in water for at least 63 days, depending on environmental conditions.

Fecal Microbiota Transplantation Reduces Campylobacter jejuni Colonization in Young Broiler Chickens Challenged by Oral Gavage but Not by Seeder Birds

Campylobacter spp., particularly C. jejuni and C. coli, are major food safety concerns, transmitted to humans mainly via contaminated poultry meat. In a previous study, we found that some commercial broiler farms consistently produced Campylobacter-free flocks while others consistently reared Campylobacter-colonized flocks, and significant differences in the gut microbiota compositions between the two types of farm categories were revealed. Therefore, we hypothesized that gut microbiota influences Campylobacter colonization in poultry and that the microbiota from Campylobacter-free flocks may confer colonization resistance to Campylobacter in the chicken intestine. In this study, two fecal microbiota transplantation (FMT) trials were performed to test the hypothesis. Newly hatched chicks were given FMT via oral gavage of the cecal content of Campylobacter-free adult chickens (treatment groups) or PBS (control groups) before the feed consumption. Approximately two weeks after the FMT, the birds were challenged with C. jejuni either by oral gavage (trial 1) or by co-mingling with Campylobacter-colonized seeder birds (trial 2) to evaluate the potential protective effect of the FMT. Cecal contents were collected (3 times, 5 days apart) to determine the Campylobacter colonization levels via culture and microbiota compositions via 16S rRNA gene sequencing. FMT reduced cecal Campylobacter colonization significantly (log10 1.2-2.54 CFU/g) in trial 1 but not in trial 2, although FMT significantly impacted the diversity and compositions of the gut microbiota in both trials. Several genera, such as Butyricimonas, Parabacteroides, Parasutterella, Bilophila, Fournierella, Phascolarctobacterium, and Helicobacter, had increased abundance in the FMT-treated groups in both trials. Furthermore, Campylobacter abundance was found to be negatively correlated with the Escherichia and Ruminococcus_torques_group genera. These findings indicate that even though FMT with adult cecal microbiota can positively affect the subsequent development of the gut microbiota in young broilers, its inhibitory effect on Campylobacter colonization varies and appears to be influenced by the challenge models.

Deciphering the Association between Campylobacter Colonization and Microbiota Composition in the Intestine of Commercial Broilers

Campylobacter is a major food safety concern and is transmitted mainly via poultry meat. We previously found that some commercial broiler farms consistently produced Campylobacter-negative flocks while others were consistently Campylobacter-positive for consecutive production cycles although the farms operated under similar management practices. We hypothesized that this difference in Campylobacter colonization might be associated with the gut microbiota composition. To address this, six commercial broiler farms were selected based on their Campylobacter status (three negative and three positive) to evaluate the microbiota differences between each farm category. For each farm on each production cycle (2-3 cycles), 40 ceca collected from five-week-old broilers were processed for microbiota analysis via 16S rRNA gene sequencing. Cecal microbiota species richness, phylogenetic diversity, community structure, and composition of Campylobacter-positive farms were noticeably different from those of Campylobacter-negative farms. Rikenella, Methanocorpusculum, Barnesiella, Parasutterella, and Helicobacter were significantly more abundant among Campylobacter-positive farms. In contrast, Ruminococcaceae, Streptococcus, Escherichia, Eggerthellaceae, Lactobacillus, Monoglobus, and Blausia were more abundant in Campylobacter-negative farms. Eggerthellaceae, Clostridia, Lachnospiraceae, Lactobacillus, Monoglobus, and Parabacteroides were significantly negatively correlated with Campylobacter abundance. These findings suggest that specific members of cecal microbiota may influence Campylobacter colonization in commercial broilers and may be further explored to control Campylobacter in poultry.

Plasmid DNA Prime/Protein Boost Vaccination against Campylobacter jejuni in Broilers: Impact of Vaccine Candidates on Immune Responses and Gut Microbiota

Campylobacter infections, traced to poultry products, are major bacterial foodborne zoonoses, and vaccination is a potential solution to reduce these infections. In a previous experimental trial using a plasmid DNA prime/recombinant protein boost vaccine regimen, two vaccine candidates (YP437 and YP9817) induced a partially protective immune response against Campylobacter in broilers, and an impact of the protein batch on vaccine efficacy was suspected. This new study was designed to evaluate different batches of the previously studied recombinant proteins (called YP437A, YP437P and YP9817P) and to enhance the immune responses and gut microbiota studies after a C. jejuni challenge. Throughout the 42-day trial in broilers, caecal Campylobacter load, specific antibodies in serum and bile, the relative expression of cytokines and β-defensins, and caecal microbiota were assessed. Despite there being no significant reduction in Campylobacter in the caecum of vaccinated groups, specific antibodies were detected in serum and bile, particularly for YP437A and YP9817P, whereas the production of cytokines and β-defensins was not significant. The immune responses differed according to the batch. A slight change in microbiota was demonstrated in response to vaccination against Campylobacter. The vaccine composition and/or regimen must be further optimised.

Transmission pathways of campylobacter spp. at broiler farms and their environment in Brandenburg, Germany

Broiler meat is widely known as an important source of foodborne Campylobacter jejuni and Campylobacter coli infections in humans. In this study, we thoroughly investigated transmission pathways that may contribute to possible Campylobacter contamination inside and outside broiler houses. For this purpose we carried out a comprehensive longitudinal sampling approach, using a semi-quantitative cultivation method to identify and quantify transmissions and reservoirs of Campylobacter spp.. Three german broiler farms in Brandenburg and their surrounding areas were intensively sampled, from April 2018 until September 2020. Consecutive fattening cycles and intervening downtimes after cleaning and disinfection were systematically sampled in summer and winter. To display the potential phylogeny of barn and environmental isolates, whole genome sequencing (WGS) and bioinformatic analyses were performed. Results obtained in this study showed very high Campylobacter prevalence in 51/76 pooled feces (67.1%) and 49/76 boot swabs (64.5%). Average counts between 6.4 to 8.36 log10MPN/g were detected in pooled feces. In addition, levels of 4.7 and 4.1 log10MPN/g were detected in boot swabs and litter, respectively. Samples from the barn interior showed mean Campyloacter values in swabs from drinkers 2.6 log10MPN/g, walls 2.0 log10MPN/g, troughs 1.7 log10MPN/g, boards 1.6 log10MPN/g, ventilations 0.9 log10MPN/g and 0.7 log10MPN/g for air samples. However, Campylobacter was detected only in 7/456 (1.5%) of the environmental samples (water bodies, puddles or water-filled wheel tracks; average of 0.6 log10MPN/g). Furthermore, WGS showed recurring Campylobacter genotypes over several consecutive fattening periods, indicating that Campylobacter genotypes persist in the environment during downtime periods. However, after cleaning and disinfection of the barns, we were unable to identify potential sources in the broiler houses. Interestingly, alternating Campylobacter genotypes were observed after each fattening period, also indicating sources of contamination from the wider environment outside the farm. Therefore, the results of this study suggest that a potential risk of Campylobacter transmission may originate from present environmental sources (litter and water reservoirs). However, the sources of Campylobacter transmission may vary depending on the operation and farm environmental conditions.

Socializing Models During Lactation Alter Colonic Mucosal Gene Expression and Fecal Microbiota of Growing Piglets

The enrichment of the social environment during lactation alleviates the stress of weaned piglets. It is significant to understand how the enriched social environment improves the weaning stress of piglets. RNA sequencing (RNA-seq) of colonic mucosa, 16S rRNA sequencing of feces, and short-chain fatty acids (SCFAs) of colonic content were used to determine the effects of social contact during lactation. In this study, thirty litter lactating piglets were divided into intermittent social contact (ISC) group that contacted with neighbors intermittently, continuous social contact (CSC) group that contacted with neighbors starting at day (D) 14 after birth, and control (CON) group in which piglets were kept in their original litter. The piglets were weaned at D35 and regrouped at D36. The colonic mucosal RNA-seq, fecal microbes, and SCFAs of colonic contents of 63-day-old piglets were analyzed. The results of RNA-seq showed that compared with the CON group, the pathways of digestion and absorption of minerals, protein, and vitamins of piglets were changed in the ISC group, whereas the pathways of retinol metabolism and nitrogen metabolism in the colonic mucosal were affected and stimulated the immune response in the CSC group. Compared with the CON group, the abundances of pernicious microorganisms (Desulfovibrio, Pseudomonas, Brevundimonas, etc.) in the CSC group and pernicious microorganisms (Desulfovibrio, Neisseria, Sutterella, etc.) and beneficial bacteria (Bifidobacterium, Megamonas, and Prevotella_9) in the ISC group were significantly higher (p < 0.05). The abundances of proinflammatory bacteria (Coriobacteriaceae_unclassified, Coprococcus_3, and Ruminococcus_2) in the CSC group were significantly increased (p < 0.05), but the abundances of SCFAs producing bacteria (Lachnospiraceae_UCG-010, Parabacteroides, Anaerotruncus, etc.) and those of anti-inflammatory bacteria (Eubacterium, Parabacteroides, Ruminiclostridium_9, and Alloprevotella) were significantly reduced (p < 0.05) in the CSC group. Compared with the CON group, the concentrations of microbial metabolites, acetate, and propionate in the colonic contents were reduced (p < 0.05) in the ISC group, whereas the concentration of acetate was reduced (p < 0.05) in the CSC group. Therefore, both ISC and CSC during lactation affected the composition of fecal microbes and changed the expression of intestinal mucosal genes related to nutrient metabolism and absorption of piglets.