The significance ofcampylobacter jejuniinfection in poultry: A review

Yeast mannan rich fraction positively influences microbiome uniformity, productivity associated taxa, and lay performance

BACKGROUND

Alternatives to antibiotic as growth promoters in agriculture, such as supplemental prebiotics, are required to maintain healthy and high performing animals without directly contributing to antimicrobial resistance bioburden. While the gut microbiota of broiler hens has been well established and successfully correlated to performance, to our knowledge, a study has yet to be completed on the effect of prebiotic supplementation on correlating the mature laying hen productivity and microbiota. This study focused on establishing the impact of a yeast derived prebiotic, mannan rich fraction (MRF), on the cecal microbiota of late laying hens. This study benefitted from large sample sizes so intra- and intergroup variation effects could be statistically accounted for.

RESULTS

Taxonomic richness was significantly greater at all taxonomic ranks and taxonomic evenness was significantly lower for all taxonomic ranks in MRF-supplemented birds (P < 0.005). Use of principal coordinate analyses and principal component analyses found significant variation between treatment groups. When assessed for compositional uniformity (an indicator of flock health), microbiota in MRF-supplemented birds was more uniform than control birds at the species level. From a food safety and animal welfare perspective, Campylobacter jejuni was significantly lower in abundance in MRF-supplemented birds. In this study, species associated with high weight gain (an anticorrelator of performance in laying hens) were significantly lower in abundance in laying hens while health-correlated butyrate and propionate producing species were significantly greater in abundance in MRF-supplemented birds.

CONCLUSIONS

The use of prebiotics may be a key factor in controlling the microbiota balance limiting agri-food chain pathogen persistence and in promoting uniformity. In previous studies, increased α- and β-diversity indices were determinants of pathogen mitigation and performance. MRF-supplemented birds in this study established greater α- and β-diversity indices in post-peak laying hens, greater compositional uniformity across samples, a lower pathogenic bioburden and a greater abundance of correlators of performance.

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.

Persistence of Campylobacter spp. in Poultry Flocks after Disinfection, Virulence, and Antimicrobial Resistance Traits of Recovered Isolates

To investigate the persistence risk of Campylobacter spp. in poultry farms, and to study the virulence and antimicrobial resistance characteristics in the recovered strains, we collected 362 samples from breeding hen flocks, before and after disinfection. The virulence factors were investigated by targeting the genes; flaA, cadF, racR, virB11, pldA, dnaJ, cdtA, cdtB, cdtC, ciaB, wlaN, cgtB, and ceuE by PCR. Antimicrobial susceptibility was tested and genes encoding antibiotic resistance were investigated by PCR and MAMA-PCR. Among the analyzed samples, 167 (46.13%) were positive for Campylobacter. They were detected in 38.7% (38/98) and 3% (3/98) of environment samples before and after disinfection, respectively, and in 126 (75.9%) out of 166 feces samples. In total, 78 C. jejuni and 89 C. coli isolates were identified and further studied. All isolates were resistant to macrolids, tetracycline, quinolones, and chloramphenicol. However, lower rates were observed for beta-lactams [ampicillin (62.87%), amoxicillin-clavulanic acid (47.3%)] and gentamicin (0.6%). The tet(O) and the cmeB genes were detected in 90% of resistant isolates. The bla_OXA-61 gene and the specific mutations in the 23S rRNA were detected in 87% and 73.5% of isolates, respectively. The A2075G and the Thr-86-Ile mutations were detected in 85% and 73.5% of macrolide and quinolone-resistant isolates, respectively. All isolates carried the flaA, cadF, CiaB, cdtA, cdtB, and cdtC genes. The virB11, pldA, and racR genes were frequent in both C. jejuni (89%, 89%, and 90%, respectively) and C. coli (89%, 84%, and 90%). Our findings highlight the high occurrence of Campylobacter strains exhibiting antimicrobial resistance with potential virulence traits in the avian environment. Thus, the improvement of biosecurity measures in poultry farms is essential to control bacterial infection persistence and to prevent the spread of virulent and resistant strains.

Prevalence, drug resistance spectrum and virulence gene analysis of Campylobacter jejuni in broiler farms in central Shanxi, China

This study collected 324 chicken cloacal swabs from 6 broiler farms in 4 different areas in Shanxi Province, China (i.e., Lvliang, Taiyuan, Jinzhong, and Yangquan), and analyzed the antimicrobial resistance and virulence-associated genes of the isolates to investigate the prevalence, drug resistance, and virulence gene data of Campylobacter jejuni in broilers. The population structure of C. jejuni and genetic evolutionary relationships among isolates from broiler farms in different regions were studied by using multilocus sequence typing. A total of 35 C. jejuni isolates with an infection rate of 10.8% (35/324) were obtained. The isolates were most resistant to ampicillin (85.7%) and were most sensitive to erythromycin (14.3%). Isolates with multidrug resistance accounted for 88.6% of the total isolates. In this experiment, 15 distinct sequence types were identified and included 9 new unique sequence types. cadF was present in all isolates, and ciaB had the lowest prevalence (51.4%). C. jejuni collected from broiler farms in central Shanxi had varied infection rates, and their overall positive rate was lower than of C. jejuni collected from other regions of the country. The isolates had high resistance to quinolones and β-lactams, and multidrug resistance was prevalent. The isolates were genotypically diverse and carried 5 virulence-associated genes at high rates. Therefore, the importance of source contamination control in broiler farms is emphasized and may have considerable effects on human and animal health.

Roles of Aerotolerance, Biofilm Formation, and Viable but Non-Culturable State in the Survival of Campylobacter jejuni in Poultry Processing Environments

Campylobacter jejuni is one of the most common causes of foodborne human gastroenteritis in the developed world. This bacterium colonizes in the ceca of chickens, spreads throughout the poultry production chain, and contaminates poultry products. Despite numerous on farm intervention strategies and developments in post-harvest antimicrobial treatments, C. jejuni is frequently detected on broiler meat products. This indicates that C. jejuni is evolving over time to overcome the stresses/interventions that are present throughout poultry production and processing. The development of aerotolerance has been reported to be a major survival strategy used by C. jejuni in high oxygen environments. Recent studies have indicated that C. jejuni can enter a viable but non-culturable (VBNC) state or develop biofilm in response to environmental stressors such as refrigeration and freezing stress and aerobic stress. This review provides an overview of different stressors that C. jejuni are exposed to throughout the poultry production chain and the genotypic and phenotypic survival mechanisms, with special attention to aerotolerance, biofilm formation, and development of the VBNC state.

Gut microbiota and age shape susceptibility to clostridial enteritis in lorikeets under human care

Background

Enteritis is a common cause of morbidity and mortality in lorikeets that can be challenging to diagnose and treat. In this study, we examine gut microbiota in two lorikeet flocks with enteritis (Columbus Zoo and Aquarium—CZA; Denver Zoo—DZ). Since 2012, the CZA flock has experienced repeated outbreaks of enteritis despite extensive diet, husbandry, and clinical modifications. In 2018, both CZA and DZ observed a spike in enteritis. Recent research has revealed that the gut microbiota can influence susceptibility to enteropathogens. We hypothesized that a dysbiosis, or alteration in the gut microbial community, was making some lorikeets more susceptible to enteritis, and our goal was to characterize this dysbiosis and determine the features that predicted susceptibility.

Results

We employed 16S rRNA sequencing to characterize the cloacal microbiota in lorikeets (CZA n = 67, DZ n = 24) over time. We compared the microbiota of healthy lorikeets, to lorikeets with enteritis, and lorikeets susceptible to enteritis, with “susceptible” being defined as healthy birds that subsequently developed enteritis. Based on sequencing data, culture, and toxin gene detection in intestinal contents, we identified Clostridium perfringens type A (CZA and DZ) and C. colinum (CZA only) at increased relative abundances in birds with enteritis. Histopathology and immunohistochemistry further identified the presence of gram-positive bacilli and C. perfringens, respectively, in the necrotizing intestinal lesions. Finally, using Random Forests and LASSO models, we identified several features (young age and the presence of Rhodococcus fascians and Pseudomonas umsongensis) associated with susceptibility to clostridial enteritis.

Conclusions

We identified C. perfringens type A and C. colinum associated with lorikeet necrohemorrhagic enteritis at CZA and DZ. Susceptibility testing of isolates lead to an updated clinical treatment plan which ultimately resolved the outbreaks at both institutions. This work provides a foundation for understanding gut microbiota features that are permissive to clostridial colonization and host factors (e.g. age, prior infection) that shape responses to infection.

Supplementary Information

The online version contains supplementary material available at 10.1186/s42523-021-00148-7.

Microbiota from Specific Pathogen-Free Mice Reduces Campylobacter jejuni Chicken Colonization

Campylobacter jejuni, a prevalent foodborne bacterial pathogen, is mainly transmitted from poultry with few effective prevention approaches. In this study, we aimed to investigate the role of microbiota on C. jejuni chicken colonization. Microbiota from specific pathogen-free (SPF) mouse stools were collected as SPF-Aerobe and SPF-Anaerobe. Birds were colonized with SPF-Aerobe or SPF-Anaerobe at day 0 and infected with C. jejuni AR101 at day 12. Notably, C. jejuni AR101 colonized at 5.3 and 5.6 log₁₀ C. jejuni CFU/g chicken cecal digesta at days 21 and 28, respectively, while both SPF-Aerobe and SPF-Anaerobe microbiota reduced pathogen colonization. Notably, SPF-Aerobe and SPF-Anaerobe increased cecal phylum Bacteroidetes and reduced phylum Firmicutes compared to those in the nontransplanted birds. Interestingly, microbiota from noninfected chickens, SPF-Aerobe, or SPF-Anaerobe inhibited AR101 in vitro growth, whereas microbiota from infected birds alone failed to reduce pathogen growth. The bacterium Enterobacter102 isolated from infected birds transplanted with SPF-Aerobe inhibited AR101 in vitro growth and reduced pathogen gut colonization in chickens. Together, SPF mouse microbiota was able to colonize chicken gut and reduce C. jejuni chicken colonization. The findings may help the development of effective strategies to reduce C. jejuni chicken contamination and campylobacteriosis.

A probiotic and mixed-enzymes combination reduces the inflammatory response, faecal shedding and systemic spread of Campylobacter jejuni in broilers

Recent research has questioned the notion that Campylobacter jejuni is a harmless resident of the avian gastrointestinal tract (GIT). The following trial examined the effect of dietary supplementation with a mixture of enzymes and Bacillus-based probiotics on growth performance, C. jejuni colonisation, GIT immune responses, faecal shedding and extra-intestinal spread in broilers. Fifty-eight, Ross 308 d-old broilers were randomly assigned to one of four treatments, giving 14 or 15 birds/pen. Birds were given nutritionally complete, complex, phased diets unsupplemented (two treatments) or supplemented (two treatments) with a multi-enzyme containing 2,000 U/kg xylanase, 200 U/kg amylase and 4,000 U/kg protease, and 75,000 cfu/g of a combination of three strains of Bacillus amyloliquefaciens. One control and one supplemented diet group contained birds orally challenged with 105 cfu C. jejuni strain M1 on d 21 of age. Among challenged birds, the mixed-enzymes and probiotic combination numerically reduced faecal C. jejuni shedding (-98% vs challenged control) three days-post-infection (d.p.i.), and at 7 d.p.i. numerically reduced C. jejuni colonisation of the ileal mucosa (-1000-fold vs control) and totally inhibited systemic spread of C. jejuni to the liver, compared to the control (P<0.05). It suppressed early pro-inflammatory chemokine response seen in the ileum, caecum and caecal tonsil tissues (at 3 d.p.i.) in challenged control birds (-18 to -46-fold; P<0.05) and altered expression of pro-inflammatory (IL-1β, IL-6, IL-17A and IL-17F) and regulatory (IL-10 and TGF-β) cytokines. The data demonstrated inhibition of a sustained pro-inflammatory response to C. jejuni infection and improved intestinal barrier integrity in supplemented birds. This highlighted the importance of looking beyond simple measurements of feed conversion and body weight gain when seeking to understand the effects and mode of action of poultry dietary interventions. Achieving a favourable balance between the gut, immune function, microbiome and nutrition should be the goal for achieving good gastrointestinal health and optimal performance.

Differential Progression of Lymphoma in Two Captive Steller's Eiders (Polysticta stelleri)

This report details 2 different presentations of lymphoma in captive Steller's eiders (Polysticta stelleri). A female Steller's eider, at least 10 years old, developed lameness and lethargy. A complete blood cell count (CBC) revealed a severely elevated total white blood cell (WBC) count with a lymphocytosis. A subsequent liver biopsy confirmed a diagnosis of lymphoma and lymphocytic leukemia. The female Steller's eider was euthanatized 11 days after presentation. On necropsy, neoplastic lymphoid infiltrates were present in multiple tissues, primarily in the skin and subcutis. The results of a CBC from an apparently healthy male Steller's eider, at least 14 years old, also indicated this bird had an increased WBC count with a lymphocytosis. Serum submitted for protein electrophoresis indicated that this bird had a monoclonal gammopathy. Lymphocytes isolated from the male Steller's eider had low levels of proliferation in response to mitogens. The bird survived nearly 2 years without treatment, and the WBC count continued to increase during this time. The male Steller's eider maintained good body condition and exhibited normal behavior throughout the course of the disease until a sudden decline just prior to death. Lymphoma was diagnosed based on histopathology results. Infiltrates of atypical lymphocytes were observed in the bone marrow, proventriculus, ventriculus, heart, and eyes.

Resveratrol Prevents Campylobacter jejuni-Induced Leaky gut by Restoring Occludin and Claudin-5 in the Paracellular Leak Pathway

Campylobacter jejuni is a bacterial human pathogen causing gastroenteritis and sequelae like irritable bowel syndrome. Epidemiologists count the human campylobacteriosis by C. jejuni as the most common foodborne zoonosis and bacterial diarrheal disease worldwide. Based on bioinformatics predictions for potential protective compounds in campylobacteriosis, the question was raised whether the plant-based polyphenol resveratrol is sufficient to attenuate intestinal epithelial damage induced by C. jejuni. We investigated this by performing experimental infection studies in an epithelial cell culture and the secondary abiotic IL-10-/- mouse model. In C. jejuni-infected human colonic HT-29/B6 cell monolayers, transepithelial electrical resistance (TER) was decreased and the paracellular marker flux of fluorescein (332 Da) increased. Concomitantly, the tight junction (TJ) proteins occludin and claudin-5 were re-distributed off the tight junction domain. This was accompanied by an increased induction of epithelial apoptosis, both changes contributing to compromised barrier function and the opening of the leak pathway induced by C. jejuni. In parallel, the recovery experiments with the application of resveratrol revealed a functional improvement of the disturbed epithelial barrier in both models in vitro and in vivo. During treatment with resveratrol, TJ localization of occludin and claudin-5 was fully restored in the paracellular domain of HT-29/B6 cells. Moreover, resveratrol decreased the rate of epithelial apoptosis. These resveratrol-induced molecular and cellular effects would therefore be expected to improve epithelial barrier function, thereby minimizing the so-called leaky gut phenomenon. In conclusion, the induction of the leak pathway by C. jejuni and the restoration of barrier function by resveratrol demonstrates its effectiveness as a potential preventive or therapeutic method of mitigating the leaky gut associated with campylobacteriosis.

Microbiota attenuates chicken transmission-exacerbated campylobacteriosis in Il10-/- mice

Campylobacter jejuni is a prevalent foodborne pathogen mainly transmitting through poultry. It remains unknown how chicken-transmitted C. jejuni and microbiota impact on human campylobacteriosis. Campylobacter jejuni AR101 (Cj-P0) was introduced to chickens and isolated as passage 1 (Cj-P1). Campylobacter jejuni Cj-P1-DCA-Anaero was isolated from Cj-P0-infected birds transplanted with DCA-modulated anaerobic microbiota. Specific pathogen free Il10-/- mice were gavaged with antibiotic clindamycin and then infected with Cj-P0, Cj-P1, or Cj-P1-DCA-Anaero, respectively. After 8 days post infection, Il10-/- mice infected with Cj-P1 demonstrated severe morbidity and bloody diarrhea and the experiment had to be terminated. Cj-P1 induced more severe histopathology compared to Cj-P0, suggesting that chicken transmission increased C. jejuni virulence. Importantly, mice infected with Cj-P1-DCA-Anaero showed attenuation of intestinal inflammation compared to Cj-P1. At the cellular level, Cj-P1 induced more C. jejuni invasion and neutrophil infiltration into the Il10-/- mouse colon tissue compared to Cj-P0, which was attenuated with Cj-P1-DCA-Anaero. At the molecular level, Cj-P1 induced elevated inflammatory mediator mRNA accumulation of Il17a, Il1β, and Cxcl1 in the colon compared to Cj-P0, while Cj-P1-DCA-Anaero showed reduction of the inflammatory gene expression. In conclusion, our data suggest that DCA-modulated anaerobes attenuate chicken-transmitted campylobacteriosis in mice and it is important to control the elevation of C. jejuni virulence during chicken transmission process.

A Review of Salmonella and Campylobacter in Broiler Meat: Emerging Challenges and Food Safety Measures

Poultry is one of the largest sources of animal-based protein in the United States. Poultry processing has grown from a small local network of plants to nearly 500 plants nationwide. Two of the most persistent bacteria in poultry processing are Salmonella and Campylobacter. It was not until the introduction of Hazard Analysis and Critical Control Point systems in 1996 that major efforts to reduce bacterial contamination were developed. Traditionally, chlorine has been the industry standard for decontaminating chicken meat. However, antimicrobials such as peracetic acid, cetylpyridinium chloride, and acidified sodium chlorite have replaced chlorine as primary antimicrobials. Despite current interventions, the emergence of stress-tolerant and biofilm-forming Salmonella and Campylobacter is of primary concern. In an effort to offset growing tolerance from microbes, novel techniques such as cold plasma treatment, electrostatic spraying, and bacteriophage-based applications have been investigated as alternatives to conventional treatments, while new chemical antimicrobials such as Amplon and sodium ferrate are investigated as well. This review provides an overview of poultry processing in the United States, major microbes in poultry processing, current interventions, emerging issues, and emerging technologies in antimicrobial treatments.

An easy-to-perform, culture-free Campylobacter point-of-management assay for processing plant applications

Aims

Current culture‐based methods for detection and determination of Campylobacter levels on processed chickens takes at least 2 days. Here we sought to develop a new complete, low‐cost and rapid (approximately 2·5 h) detection system requiring minimal operator input.

Methods and Results

We observed a strong correlation between culture‐based cell counts and our ability to detect either Campylobacter jejuni or Campylobacter coli by loop‐mediated isothermal amplification from the same samples. This knowledge was used to develop a rapid and simple five‐step assay to quantify Campylobacter, which was subsequently assessed for its specificity, reproducibility and accuracy in quantifying Campylobacter levels from processed chickens. The assay was found to be highly specific for C. jejuni and C. coli and was capable of distinguishing between samples that are either within or exceeding the industry set target of 6000 Campylobacter colony forming units (CFU) per carcass (equivalent to 12 CFU per ml of chicken rinse) with >90% accuracy relative to culture‐based methods.

Conclusions

Our method can reliably quantify Campylobacter counts of processed chickens with an accuracy comparable to culture‐based assays but provides results within hours as opposed to days.

Significance and Impact of the Study

The research presented here will help improve food safety by providing fast Campylobacter detection that will enable the implementation of real‐time risk management strategies in poultry processing plants to rapidly test processed chickens and identify effective intervention strategies. This technology is a powerful tool that can be easily adapted for other organisms and thus could be highly beneficial for a broad range of industries.

A Review of the Effect of Management Practices on Campylobacter Prevalence in Poultry Farms

Poultry is frequently associated with campylobacteriosis in humans, with Campylobacter jejuni being the most usual Campylobacter associated with disease in humans. Far-reaching research on Campylobacter was undertaken over the past two decades. This has resulted in interventions being put in place on farms and in processing plants. Despite these interventions, coupled with increased media coverage to educate the consumer on Campylobacter prevalence and campylobacteriosis, human health incidents are still high. Recent research is now shifting toward further understanding of the microorganisms to challenge interventions in place and to look at further and more relevant interventions for the reduction in human incidents. Farm practices play a key role in the control of colonization within poultry houses and among flocks. Prevalence at the farm level can be up to 100% and time of colonization may vary widely between flocks. Considerable research has been performed to understand how farm management and animal health practices can affect colonization on farms. This review will focus on farm practices to date as a baseline for future interventions as the microorganism becomes better understood. Further research is required to understand the chicken microbiome and factors influencing vertical transmission. The persistence of Campylobacter in animal and environmental reservoirs within and around farms requires further investigation to tailor farm practices toward preventing such reservoirs. IMPLICATIONS  This review gives an overview of farm practices and their effect on Campylobacter prevalence in poultry. Various elements of farm practices have been captured in this review.

Sources of contamination, prevalence, and antimicrobial resistance of thermophilic Campylobacter isolated from turkeys

AIM

Sources of contamination, prevalence, and antimicrobial susceptibility of thermophilic Campylobacter isolated from turkey samples were determined.

MATERIALS AND METHODS

A total of 300 samples were collected from 3 farms (fecal droppings) and 4 poultry slaughterhouses (neck skins and ceca) located in the middle area of Algeria (Algiers, Boumerdès, and Bouira). After detection, an antibiogram was realized only for slaughterhouses samples.

RESULTS

Samples from cecum (90.0%, 90/100; 95% confidence interval (CI)=84.1-95.9%), fecal dropping (68.0%, 68/100; 95% CI=58.9-77.1%), and neck skin (55.0%, 55/100; 95% CI=45.2-64.8%) were positive for thermophilic Campylobacter (p<0.05). Contamination rate of turkey carcasses was higher in modern slaughterhouse (96.7%) than in traditional slaughterhouses (37.1%) (p<0.05). Isolated strains were resistant to nalidixic acid (NA) (87.5%), tetracycline (TE) (81.3%), ciprofloxacin (CIP) (75.0%), ampicillin (AM) (65.6%), and erythromycin (25.0%) (p<0.05). 96.9% (124/128) of the isolates were multiresistant and 18 drug resistance patterns were registered. The predominant one (43.0%) was AM, NA, CIP, and TE.

CONCLUSIONS

Potential sources of contamination of this fastidious bacterium were noticed in farms and slaughterhouses. Modern slaughterhouse allowed contamination of turkey carcasses more than a traditional slaughterhouse. However, the scalding step could not represent a source of contamination. The most tested strains exhibited resistance to erythromycin and/or CIP. It is worrisome because these molecules are considered as first-choice antibiotics for human campylobacteriosis.

Improvement of Karmali Agar by Supplementation with Tazobactam for Detecting Campylobacter in Raw Poultry

In this study, Karmali agar was modified by adding tazobactam (T-Karmali agar) to suppress the growth of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli , which frequently contaminates raw poultry meat. By inoculating 30 Campylobacter spp. strains and 25 ESBL-producing E. coli strains onto Karmali agar and T-Karmali agar containing various concentrations of the antibacterial agent, we determined the optimum concentration of tazobactam to be 4 mg/liter. The Campylobacter spp. isolation rate on T-Karmali agar (13.3%) was higher than that on Karmali agar (8.3%), although the difference was not significant (P > 0.05). However, T-Karmali agar showed a significantly greater selectivity than Karmali agar, as evaluated by comparing the numbers of contaminated agar plates (20.8 versus 82.5%; P < 0.05) and the growth indexes (1.36 versus 2.83) of competing flora. The predominant competing flora on Karmali and T-Karmali agar were identified as ESBL-producing E. coli . Thus, T-Karmali agar might be effective for determining the real prevalence of Campylobacter in raw poultry and, especially, contamination with ESBL-producing E. coli .

Effect of Feed Form and Whole Grain Feeding on Gastrointestinal Weight and the Prevalence of Campylobacter jejuni in Broilers Orally Infected

Two independent trials were carried out to evaluate the effect of feed form, whole wheat (WW) and oat hulls (OH) addition on gastrointestinal (GIT) weight and Campylobacter jejuni colonization in orally infected birds. In Trial 1, there were six treatments factorially arranged with two feed forms (mash vs pellets), and three levels of WW from 1-21/22-42d: 0/0, 7.5/15%, 15/30%. Broilers were allocated in cages (3 birds/cage, 12 cages/treatment). In Trial 2, there were three treatments: a mash diet, a mash diet including WW (7.5% from 1-21 and 15% from 22-42d), and a third treatment including also 5%OH. Broilers were allocated in floor pens (1 pen with 30 birds/treatment). At 14d, all broilers in Trial 1 or 3 broilers/pen in Trial 2 were orally challenged with 1.5 x 105 cfu of C. jejuni ST-45 /. In Trial 1, birds fed pelleted diets consumed 13.5% more feed, gained 31% more weight, and presented 12.9% better feed conversion for the whole trial (P<0.05). Pelleting decreased the relative weight of GIT and gizzard and increased the relative weight of proventriculus (P<0.05). Mash diets decreased pH in the gizzard (P<0.05). Inclusion of WW decreased the relative weight of proventriculus, increased gizzard weight, and reduced pH in the gizzard (P<0.05). At 21d of age, mash tended to reduce C. jejuni compared to pellets (7.85 vs 8.27 log10cfu/g; P = 0.091) and WW inclusion at 7.5/15% reduced C. jejuni colonization when compared to lower and higher inclusion (P<0.05). In Trial 2, birds fed T3 (WW+OH) showed 1.38 log10cfu/g less than birds fed Control diet (P<0.05). In conclusion, despite of the clear morphological changes in the GIT derived of FF and WW inclusion, no clear reductions in C. jejuni populations in the ceca were observed. However, WW and OH inclusion to mash diets significantly reduced cecal C. jejuni colonization at 42 days.

Prevalence and Distribution of Campylobacter jejuni in Small-Scale Broiler Operations

Campylobacter jejuni has been recognized as one of the most prevalent causes of foodborne bacterial illnesses in humans. Previous studies have focused on the transmission routes of C. jejuni from commercial flock farms to the final retail product. The objective of this study was to determine the prevalence of C. jejuni and Campylobacter spp. in eggshells, live birds, feed, drinking water, and the rearing environment in a small-scale broiler operation. Broilers were raised under two different production systems: (i) environmentally controlled housing and (ii) open-air housing with two replications. Each week, samples were collected from eggshells, bird feces, feed, drinking water, enclosures (vertical walls of bird housing), and feed troughs for enumeration and isolation testing. All samples were plated on modified charcoal-cefoperazone-deoxycholate agar to determine the log CFU per gram and percent prevalence of Campylobacter spp. Isolation of C. jejuni was verified with latex agglutination and hippurate hydrolysis tests. The results from this study suggest that vertical transmission of these bacteria from egg surfaces to newly hatched chicks is not a significant risk factor. The results also suggest that the prevalence of C. jejuni at time of harvest (week 6) was significantly higher (P < 0.05) in the open-air housing broilers than in those in the environmentally controlled housing. Elevated levels of cross-contaminants, especially water and feed, may have played a role in this outcome.

Campylobacter in Poultry: Ecology and Potential Interventions

Avian hosts constitute a natural reservoir for thermophilic Campylobacter species, primarily Campylobacter jejuni and Campylobacter coli, and poultry flocks are frequently colonized in the intestinal tract with high numbers of the organisms. Prevalence rates in poultry, especially in slaughter-age broiler flocks, could reach as high as 100% on some farms. Despite the extensive colonization, Campylobacter is essentially a commensal in birds, although limited evidence has implicated the organism as a poultry pathogen. Although Campylobacter is insignificant for poultry health, it is a leading cause of food-borne gastroenteritis in humans worldwide, and contaminated poultry meat is recognized as the main source for human exposure. Therefore, considerable research efforts have been devoted to the development of interventions to diminish Campylobacter contamination in poultry, with the intention to reduce the burden of food-borne illnesses. During the past decade, significant advance has been made in understanding Campylobacter in poultry. This review summarizes the current knowledge with an emphasis on ecology, antibiotic resistance, and potential pre- and postharvest interventions.

Passive immunization with hyperimmune egg-yolk IgY as prophylaxis and therapy for poultry diseases – A review

Passive immunization with pathogen-specific egg yolk antibodies (IgY) is emerging as a potential alternative to antibiotics for the treatment and prevention of various human and animal diseases. Laying hens are an excellent source of high-quality polyclonal antibodies, which can be collected noninvasively from egg yolks. The use of IgY offers several advantages in that it is environmentally friendly, nontoxic, and reduces the numbers of animals required for antibody production. This paper reviews the use of IgY antibodies in the treatment and prevention of enteric pathogen infections in poultry. Brief descriptions of the production, structure, and properties of IgY are also presented. Some limitations of the technology and future perspectives are discussed.

Virulence characterization of Campylobacter jejuni isolated from resident wild birds in Tokachi area, Japan

The prevalence of Campylobacter jejuni in wild birds is a potential hazard for human and animal health. The aim of this study was to establish the prevalence of C. jejuni in wild birds in Tokachi area, Hokkaido, Japan and investigate their virulence in vitro. In total, 173 cloacal swabs from individual wild birds were collected for the detection of Campylobacter spp. Thirty four samples (19.7%) were positive for Campylobacter of which 94.1% (32/34 samples) were C. jejuni. Additionally, one C. coli and one C. fetus were isolated. Seven C. jejuni isolates (one from crows and the other from pigeons) had important virulence genes including all three CDT genes (cdtA, cdtB and cdtC) and flaA, flaB, ciaB and cadF, and the other isolates were lacking cdtA gene. Further studies on in vitro virulence-associated phenotypes, such as motility assay on soft agar and invasion assay in Caco-2 cells, were performed. The wild bird C. jejuni isolates adhered and invaded human cells. Although the numbers of viable intracellular bacteria of wild bird isolates were lower than a type strain NCTC11168, they persisted at 48-hr and underwent replication in host cells.

Molecular epidemiology and characterization of Campylobacter spp. isolated from wild bird populations in northern England

Campylobacter infections have been reported at prevalences ranging from 2 to 50% in a range of wild bird species, although there have been few studies that have investigated the molecular epidemiology of Campylobacter spp. Consequently, whether wild birds are a source of infection in humans or domestic livestock or are mainly recipients of domestic animal strains and whether separate cycles of infection occur remain unknown. To address these questions, serial cross-sectional surveys of wild bird populations in northern England were carried out over a 2-year period. Fecal samples were collected from 2,084 wild bird individuals and screened for the presence of Campylobacter spp. A total of 56 isolates were recovered from 29 birds sampled at 15 of 167 diverse locales. Campylobacter jejuni, Campylobacter lari, and Campylobacter coli were detected by PCR, and the prevalences of different Campylobacter spp. in different avian families ranged from 0% to 33%. Characterization of 36 C. jejuni isolates by multilocus sequence typing revealed that wild birds carry both livestock-associated and unique strains of C. jejuni. However, the apparent absence of unique wild bird strains of C. jejuni in livestock suggests that the direction of infection is predominantly from livestock to wild birds. C. lari was detected mainly in wild birds sampled in an estuarine or coastal habitat. Fifteen C. lari isolates were analyzed by macrorestriction pulsed-field gel electrophoresis, which revealed genetically diverse populations of C. lari in Eurasian oystercatchers (Haematopus ostralegus) and clonal populations in magpies (Pica pica).

Co-infection dynamics of a major food-borne zoonotic pathogen in chicken

A major bottleneck in understanding zoonotic pathogens has been the analysis of pathogen co-infection dynamics. We have addressed this challenge using a novel direct sequencing approach for pathogen quantification in mixed infections. The major zoonotic food-borne pathogen Campylobacter jejuni, with an important reservoir in the gastrointestinal (GI) tract of chickens, was used as a model. We investigated the co-colonisation dynamics of seven C. jejuni strains in a chicken GI infection trial. The seven strains were isolated from an epidemiological study showing multiple strain infections at the farm level. We analysed time-series data, following the Campylobacter colonisation, as well as the dominant background flora of chickens. Data were collected from the infection at day 16 until the last sampling point at day 36. Chickens with two different background floras were studied, mature (treated with Broilact, which is a product consisting of bacteria from the intestinal flora of healthy hens) and spontaneous. The two treatments resulted in completely different background floras, yet similar Campylobacter colonisation patterns were detected in both groups. This suggests that it is the chicken host and not the background flora that is important in determining the Campylobacter colonisation pattern. Our results showed that mainly two of the seven C. jejuni strains dominated the Campylobacter flora in the chickens, with a shift of the dominating strain during the infection period. We propose a model in which multiple C. jejuni strains can colonise a single host, with the dominant strains being replaced as a consequence of strain-specific immune responses. This model represents a new understanding of C. jejuni epidemiology, with future implications for the development of novel intervention strategies.

Pathogenic bacteria that can be transferred from animals to humans represent a highly potent human health hazard. Understanding the ecology of these pathogens in the animal host is of fundamental importance. A major analytical challenge, however, is the fact that individual animal hosts can be colonised by multiple strains of a given pathogen. We have addressed this challenge by developing a novel high-throughput approach for analyses of mixed strain infections. We chose Campylobacter jejuni colonisation of the chicken gastrointestinal (GI) tract as a model. C. jejuni is a major cause of food-borne disease in humans, and chickens are considered a main reservoir from which this bacterium may enter the food chain. We analysed the co-colonisation of seven C. jejuni strains in two groups of chickens with very different background GI microfloras. We found that mainly two of the C. jejuni strains colonised the chickens, with a shift in the dominant coloniser during the infection period. The C. jejuni colonisation pattern, however, was little affected by the dominating GI microflora. We propose a model where the chicken immune response is the important determinant for C. jejuni colonisation, and suggest that multiple strain colonisation could be a way of maintaining stable infections in the animal host. This new knowledge is very important for future development of novel intervention strategies to prevent C. jejuni from entering the human food chain.

Prevalence and risk factors for Salmonella spp. and Campylobacter spp. caecal colonization in broiler chicken and turkey flocks slaughtered in Quebec, Canada

We conducted an observational study to estimate prevalence and risk factors for Salmonella spp. and Campylobacter spp. caecal colonization in poultry. Eighty-one broiler chicken and 59 turkey flocks selected among flocks slaughtered in the province of Quebec, Canada, were included in the study. Flock status was evaluated by culturing pooled caecal contents from about 30 birds per flock. Exposure to potential risk factors was evaluated with a questionnaire. Odds ratios were computed using multivariable logistic regression. The prevalence of Salmonella-positive flocks was 50% (95% CI: 37, 64) for chickens and 54% (95% CI: 39, 70) for turkeys, respectively. Odds of Salmonella colonization were 2.6 times greater for chicken flocks which failed to lock the chicken house permanently. In turkeys, odds of Salmonella colonization were 4.8-7.7 times greater for flocks which failed to be raised by <or=2 producers with no other visitors allowed onto the premises, or origin from a hatchery. The prevalence of Campylobacter-positive flocks was 35% (95% CI: 22, 49) for chickens and 46% (95% CI: 30, 62) for turkeys. Odds of colonization were 4.1 times higher for chicken flocks raised on farms with professional rodent control and 5.2 times higher for flocks with manure heap >200m from the poultry house, and also increased with the number of birds raised per year on the farm and with the age at slaughter. For turkeys, odds of Campylobacter flock colonization were 3.2 times greater in flocks having a manure heap at </=200m from poultry house and 4.2 times greater in flocks drinking unchlorinated water.

Modelling of Campylobacter survival in frozen chicken meat

AIMS

To model the survival kinetics of Campylobacter jejuni on frozen chicken meat.

METHODS AND RESULTS

Three different types of chicken meat surface (skin, skinned muscle and cut muscle) were inoculated with stationary phase cells of C. jejuni (8 log(10) CFU cm(-2)) and frozen for 5 weeks at -20 degrees C. Bacterial numbers were determined weekly using two different methods of enumeration to quantify uninjured and injured cells. Analysis of variance of the results showed that the type of chicken surface and the method used to enumerate surviving cells were the most significant sources of variations in the numbers recovered (P < 0.0001), much more than the freezing time. To identify an appropriate model for the description of effects of freezing on survival over time, several models were fitted to the count data. Decay was found to be nonlinear. In general, survival was least on skin, better on skinned muscle and best on cut muscle. After 2 weeks, additional inactivation by freezing appeared to be negligible.

CONCLUSION

Because of the variability of survival it was not possible to fit and select a general model useful for all the different surfaces types.

SIGNIFICANCE AND IMPACT OF THE STUDY

The injured state of the cells leads to variability and the underestimation of bacterial survival. This is an essential factor for the assessment of Campylobacter-associated risk.

Pathogenesis of Helicobacter pullorum infections in broilers

Four groups of 23 one-day-old broiler chickens were each inoculated by gavage with a different Helicobacter pullorum strain isolated from humans or poultry. As a control, a fifth group of eight animals was inoculated with phosphate-buffered saline. Faecal samples were collected weekly and tested for the presence of H. pullorum DNA using PCR. At 1, 8, 15, 22 and 42 days postinoculation, birds were euthanized and samples from the liver and intestinal tract were histologically, immunohistochemically and bacteriologically examined. The samples were also tested for the presence of H. pullorum DNA by PCR. All animals remained clinically healthy throughout the experiment although mild lesions in the caeca were present in animals inoculated with H. pullorum. In all H. pullorum-inoculated groups, DNA of this bacterium was detected in faecal samples until 42 days postinoculation. The main site of colonization was the caecum. Immunohistochemical examination revealed that the bacterium was closely associated with the caecal epithelial cells. It was concluded that H. pullorum may colonize the caecum of broilers and is excreted in their faeces until slaughter age. This implies that chicken meat might constitute a source of infection for human beings.

Correlation Between In Vitro Secretion of Virulence-Associated Proteins of Campylobacter jejuni and Colonization of Chickens

The mechanisms used by Campylobacter jejuni to colonize the (chicken) intestinal tract have not been defined. In this study, we obtained evidence that in the presence of chicken serum and mucus, C. jejuni secreted proteins that may play a role in the colonization of chicken gut (Campylobacter invasion antigen = Cia). C. jejuni strains NCTC11168V1 and 81-176, as well as an NCTC11168V1 flaA mutant, were found to colonize intestinal tract and secrete proteins in the presence of chicken mucus, chicken serum, or fetal bovine serum in cell culture-conditioned medium. C. jejuni strain NCTC11168V26, which was observed to be a poor colonizer compared with the other C. jejuni isolates, did not secrete Cia proteins. Secreted proteins were also recognized by Western immunoblot using sera from birds that had been colonized by C. jejuni. These data suggest that C. jejuni secretes Cia proteins during colonization of chicken gut and that these Cia proteins play an important role in colonization.

Survival of Campylobacter jejuni in waterborne protozoa

The failure to reduce the Campylobacter contamination of intensively reared poultry may be partially due to Campylobacter resisting disinfection in water after their internalization by waterborne protozoa. Campylobacter jejuni and a variety of waterborne protozoa, including ciliates, flagellates, and alveolates, were detected in the drinking water of intensively reared poultry by a combination of culture and molecular techniques. An in vitro assay showed that C. jejuni remained viable when internalized by Tetrahymena pyriformis and Acanthamoeba castellanii for significantly longer (up to 36 h) than when they were in purely a planktonic state. The internalized Campylobacter were also significantly more resistant to disinfection than planktonic organisms. Collectively, our results strongly suggest that protozoa in broiler drinking water systems can delay the decline of Campylobacter viability and increase Campylobacter disinfection resistance, thus increasing the potential of Campylobacter to colonize broilers.

Occurrence of Campylobacter and Listeria monocytogenes in a poultry processing plant

The occurrence of Campylobacter and Listeria monocytogenes was studied in 645 samples from surfaces, water, and poultry products (chicken carcasses, chicken parts, viscera, and spoils) in a poultry processing plant in southern Brazil. The automated mini-VIDAS system was used to detect the presence of Campylobacter and L. monocytogenes on the samples. The positive samples were confirmed by conventional methods. Campylobacter and L. monocytogenes were found in 16.6 and 35.6% of the analyzed samples, respectively. The sampling points with the highest Campylobacter incidence were intestine (63.3%, 19 of 30 samples), gallbladder (46.7%, 14 of 30), carcasses before evisceration (33.33%, 10 of 30), and carcasses after plucking (30%, 9 of 30). For L. monocytogenes, the majority of positive samples were from frozen breast (100%, 15 of 15 samples), frozen wing (93.3%, 14 of 15), fresh breast (83.3%, 25 of 30), fresh wing (80%, 24 of 30), skin of breast and leg (76.7%, 23 of 30), frozen leg (60%, 9 of 15), and fresh leg (50%, 15 of 30).

Campylobacter jejuni-induced cytokine responses in avian cells

Campylobacter jejuni is a major cause of human inflammatory enteritis. During the course of human disease numerous proinflammatory cytokines are produced. Little is known, however, about the cytokine responses produced during the interaction of this bacterium with the avian host. Campylobacter has been considered a commensal of the avian host. Any differences in innate responses to this pathogen between the human and avian hosts should lead to a greater understanding of the disease process in humans. We have demonstrated expression of proinflammatory cytokines and chemokines in response to Campylobacter infection in avian primary chick kidney cells and the avian macrophage cell line HD11. The data indicate that Campylobacter can stimulate the avian host in a proinflammatory manner. The data strongly suggest that the lack of pathology in vivo is not due to an inability of Campylobacter to stimulate a proinflammatory response from avian cells.

Detection of Campylobacter or Salmonella in Turkey Semen and the Ability of Poultry Semen Extenders to Reduce Their Concentrations

Campylobacter and Salmonella are the most commonly reported pathogens causing foodborne illness in the United States. In turkeys, the potential that semen used for artificial insemination is contaminated with these foodborne pathogens has not been investigated. Because semen on turkey farms is pooled and then used to inseminate multiple hens, contaminated semen could easily spread these bacteria throughout entire flocks via artificial insemination. The objectives of this study were to 1) determine if semen from commercial turkey farms contained these foodborne pathogens and 2) if present, evaluate the efficacy of semen extenders to reduce or eliminate Campylobacter and Salmonella from semen. Semen was collected from randomized pools of ejaculates from 10 to 30 toms per farm from 6 flocks over a 7-wk period and, on occasion, was found to contain Campylobacter, Salmonella, or both. To evaluate the efficacy of semen extenders to reduce or eliminate pathogens, pooled ejaculates were challenged with Campylobacter or Salmonella and treated with commercial poultry extenders containing various concentrations of antibiotics or an antibiotic combination previously demonstrated to remove Campylobacter from mammalian semen. Results demonstrate that commercial turkey semen may contain Campylobacter or Salmonella, and the semen extenders tested either did not reduce the bacteria or reduced but did not eliminate these bacteria from semen. We concluded that semen may be a potential vehicle for Campylobacter transfer to hens, and, if this is true, development of a method for eliminating pathogens in semen before insemination could reduce the risk of colonization.

Effects of Aeration and Storage Temperature on Campylobacter Concentrations in Poultry Semen

Campylobacter is one of the most commonly reported bacterial causes of human foodborne infections in the United States. Recent evidence has demonstrated that Campylobacter is present in poultry semen and may contribute to the vertical transmission between the breeder hen and offspring. As Campylobacter is considered sensitive to oxygen and cold temperature, the objective of this study was to determine if aeration and storage temperature could reduce or eliminate Campylobacter in poultry semen. In 4 separate trials, pooled semen samples were collected from roosters or toms, diluted with a commercial poultry semen extender, and inoculated with an average of 10(7) cells/mL of a wild-type C. jejuni or C. coli semen isolate. Pooled ejaculates were then divided into 3 aeration treatments: Control (no aeration), air, or oxygen (gently bubbled for 20 min with atmospheric air or oxygen, respectively). Immediately after aeration, pooled semen samples were further divided to 3 test storage temperatures: 4, 23, or 42 degrees C. At 0, 2, 6, and 24 h of storage, samples were enumerated for Campylobacter. Aeration of the semen alone, or aeration with reduced temperatures (4 or 23 degrees C), did not reduce the amount of Campylobacter compared with the controls. Campylobacter concentrations were, however, reduced when stored at 42 degrees C for 24 h. This effect is associated with reduced sperm viability and is therefore not a practical treatment of reducing Campylobacter in semen. It appears alternative methods will be needed to eliminate Campylobacter from poultry semen.

Direct real-time PCR quantification of Campylobacter jejuni in chicken fecal and cecal samples by integrated cell concentration and DNA purification

Campylobacter jejuni is a major cause of diarrheal disease and food-borne gastroenteritis. The main reservoir of C. jejuni in poultry is the cecum, with an estimated content of 6 to 8 log10 CFU/g. If a flock is infected with C. jejuni, the majority of the birds in that flock will harbor the bacterium. Diagnostics at the flock level could thus be an important control point. The aim of the work presented here was to develop a complete quantitative PCR-based detection assay for C. jejuni obtained directly from cecal contents and fecal samples. We applied an approach in which the same paramagnetic beads were used both for cell isolation and for DNA purification. This integrated approach enabled both fully automated and quantitative sample preparation and a DNA extraction method. We developed a complete quantitative diagnostic assay through the combination of the sample preparation approach and real-time 5'-nuclease PCR. The assay was evaluated both by spiking the samples with C. jejuni and through the detection of C. jejuni in naturally colonized chickens. Detection limits between 2 and 25 CFU per PCR and a quantitative range of >4 log10 were obtained for spiked fecal and cecal samples. Thirty-one different poultry flocks were screened for naturally colonized chickens. A total of 262 (204 fecal and 58 cecal) samples were analyzed. Nineteen of the flocks were Campylobacter positive, whereas 12 were negative. Two of the flocks contained Campylobacter species other than C. jejuni. There was a large difference in the C. jejuni content, ranging from 4 to 8 log10 CFU/g of fecal or cecal material, for the different flocks tested. Some issues that have not yet promoted much attention are the prequantitative differences in the ability of C. jejuni to colonize poultry and the importance of these differences for causing human disease through food contamination. Understanding the colonization kinetics in poultry is therefore of great importance for controlling human infections by this bacterium.

Cattle and sheep farms as reservoirs of Campylobacter

AIM

This is a review of the natural Campylobacter colonization and transmission among ruminant livestock in the dairy farm environment.

METHODS AND RESULTS

Using cultural detection methods and enumeration techniques the distribution of Campylobacter in ruminant animals at birth, on the farm, at slaughter and in the farm environment have been examined. Colonization and shedding rates are higher among young animals while patterns of shedding in adult animals may be seasonal. Stored and land-dispersed slurries provide a reservoir for scavenging birds and flies and a source for runoff.

CONCLUSIONS

The dairy farm plays a significant role in the dissemination of Campylobacter subtypes that can cause disease in the human community.

SIGNIFICANCE AND IMPACT OF STUDY

An understanding of the role of the dairy farm in the environmental cycle of Campylobacter is required in order to devise intervention strategies.

Campylobacter colonization in poultry: sources of infection and modes of transmission

Since its recognition as a human pathogen in the early 1970s, Campylobacter jejuni has now emerged as the leading bacterial cause of food-borne gastroenteritis in developed countries. Poultry, particularly chickens, account for the majority of human infections caused by Campylobacter. Reduction or elimination of this pathogen in the poultry reservoir is an essential step in minimizing the public health problem; however, farm-based intervention measures are still not available because of the lack of understanding of the ecological aspects of C. jejuni on poultry farms. Although Campylobacter is highly prevalent in poultry production systems, how poultry flocks become infected with this organism is still unknown. Many investigations indicate that horizontal transmission from environmental sources is the primary route of flock infections by Campylobacter. However, some recent studies also suggest the possibility of vertical transmission from breeder to progeny flocks. The transmission of the organism is not well understood, but it is likely to be through both vertical and horizontal transmission and may be affected by the immune status of the poultry host and the environmental conditions in the production system. Intervention strategies for Campylobacter infection in poultry should consider the complex nature of its transmission and may require the use of multiple approaches that target different segments of the poultry production system.

Prevalence of thermophilic Campylobacter spp. in ready-to-eat foods and raw poultry in Northern Ireland

Although there have been numerous studies investigating the prevalence of campylobacters in animals and raw meats, there are limited data on the persistence of these organisms in ready-to-eat (RTE) foodstuffs. Although poultry is now well established as a major reservoir of thermophilic campylobacters, it is widely assumed that hazard analysis critical control point (HACCP) controls in commercial and industrial settings are effective in eliminating this hazard through thorough cooking of RTE products. Therefore, it was the primary aim of this study to investigate the effectiveness of HACCP controls in eliminating campylobacters in such cooked RTE foods by attempting to isolate viable organisms from product. Concurrently, the results of this study demonstrate that local poultry is highly contaminated with campylobacters. Commercially available RTE foodstuffs (n = 2,030) consisting of 1,061 poultry-related cooked products and 969 other products were analyzed and were not found to contain thermophilic Campylobacter spp. In addition, 107 raw chickens (63 fresh birds and 44 frozen birds) were sampled, and 94% of the fresh birds and 77% of the frozen birds examined were demonstrated to be contaminated with campylobacters, with Campylobacter jejuni, Campylobacter coli, and Campylobacter lari accounting for 69, 30, and 1% of the contaminating organisms, respectively. In general, commercially available RTE foodstuffs, including cooked poultry, are not commonly contaminated with campylobacters and thus do not appear to represent a significant cause of clinical infection of Campylobacter spp. in Northern Ireland. However, raw poultry produce, including fresh and frozen chicken, frequently tested positive for campylobacters. Implementation of HACCP systems by food processors will help to minimize and/or eliminate the risk posed by this organism to the consumer.

Effect of drinking water chlorination on Campylobacter spp. colonization of broilers

The main source for Campylobacter spp. transmission from the environment to broiler chickens is still unclear. One implicated reservoir for the organism has been untreated broiler drinking water. This study was conducted with broilers first using experimental conditions (isolation units) and second under commercial conditions. We compared the rate of intestinal colonization in chickens provided 2 to 5 parts per million (ppm) chlorinated drinking water in relation to the frequency of colonization in chickens given unsupplemented drinking water. No significant difference (P > 0.05) was detected in isolation frequency or level of Campylobacter spp. colonization in birds provided chlorinated drinking water and control birds provided water without supplemental chlorine. In the isolation unit experiments, 86.3% (69/80) of the control and 85.0% (68/80) of the treated birds were colonized at levels corresponding to an average of 10(5.2) and 10(5.1) log colony-forming units (cfu) Campylobacter spp./g of cecal contents, respectively. Additionally, two sets of paired 20,000 bird broiler houses, with and without chlorination (2-5 ppm chlorine), were monitored in a commercial field trial. Effectiveness of chlorination was judged by prevalence of Campylobacter spp. in fecal droppings (960 samples) taken from the flocks in treated and control houses. Birds from the control houses were 35.5% (175/493) Campylobacter spp. positive, while 45.8% (214/467) of the samples from the houses having chlorinated drinking water yielded the organism. Chlorination of flock drinking water at the levels tested in this study was not effective in decreasing colonization by Campylobacter spp. under commercial production practices presently used in the United States.

Prevalence, antigenic specificity, and bactericidal activity of poultry anti-Campylobacter maternal antibodies

Poultry are considered the major reservoir for Campylobacter jejuni, a leading bacterial cause of human food-borne diarrhea. To understand the ecology of C. jejuni and develop strategies to control C. jejuni infection in the animal reservoir, we initiated studies to examine the potential role of anti-Campylobacter maternal antibodies in protecting young broiler chickens from infection by C. jejuni. Using an enzyme-linked immunosorbent assay (ELISA), the prevalence of anti-C. jejuni antibodies in breeder chickens, egg yolks, and broilers from multiple flocks of different farms were examined. High levels of antibodies to the organism were detected in serum samples of breeder chickens and in egg yolk contents. To determine the dynamics of anti-Campylobacter maternal antibody transferred from yolks to hatchlings, serum samples collected from five broiler flocks at weekly intervals from 1 to 28 or 42 days of age were also examined by ELISA. Sera from the 1-day and 7-day-old chicks showed high titers of antibodies to C. jejuni. Thereafter, antibody titers decreased substantially and were not detected during the third and fourth weeks of age. The disappearance of anti-Campylobacter maternal antibodies during 3 to 4 weeks of age coincides with the appearance of C. jejuni infections observed in many broiler chicken flocks. As shown by immunoblotting, the maternally derived antibodies recognized multiple membrane proteins of C. jejuni ranging from 19 to 107 kDa. Moreover, in vitro serum bactericidal assays showed that anti-Campylobacter maternal antibodies were active in antibody-dependent complement-mediated killing of C. jejuni. Together, these results highlight the widespread presence of functional anti-Campylobacter antibodies in the poultry production system and provide a strong rationale for further investigation of the potential role of anti-C. jejuni maternal antibodies in protecting young chickens from infection by C. jejuni.

Competitive exclusion of heterologous Campylobacter spp. in chicks

Chicken and human isolates of Campylobacter jejuni were used to provide oral challenge of day-old broiler chicks. The isolation ratio of the competing challenge strains was monitored and varied, depending upon the isolates used. A PCR-restriction fragment length polymorphism assay of the flagellin gene (flaA) was used to discriminate between the chick-colonizing isolates. Our observations indicated that the selected C. jejuni colonizers dominated the niche provided by the chicken ceca. Chicken isolates from the flaA type 7 grouping generally had numerical superiority over the human isolates when they were administered in our 1-day-old chick model. Our results suggest that it is possible to use combinations of C. jejuni chicken isolates as a defined bacterial preparation for the competitive exclusion of human-pathogenic C. jejuni in poultry.