Campylobacter Colonization Research Articles

Spatio-temporal patterns ofCampylobactercolonization in Danish broilers

Despite a number of risk-factor studies in different countries, the epidemiology of Campylobacter colonization in broilers, particularly spatial dependencies, is still not well understood. A series of analyses (visualization and exploratory) were therefore conducted in order to obtain a better understanding of the spatial and temporal distribution of Campylobacter in the Danish broiler population. In this study, we observed a non-random temporal occurrence of Campylobacter, with high prevalence during summer and low during winter. Significant spatio-temporal clusters were identified in the same areas in the summer months from 2007 to 2009. Range of influence between broiler farms were estimated at distances of 9.6 km and 13.5 km in different years. Identification of areas and time with greater risk indicates variable presence of risk factors with space and time. Implementation of safety measures on farms within high-risk clusters during summer could have an impact in reducing prevalence.

Evaluating the efficacy of an avian-specific probiotic to reduce the colonization ofCampylobacter jejuni in broiler chickens

Campylobacteriosis is the most frequent zoonotic disease in humans worldwide, and the contaminated poultry meat by Campylobacter jejuni can be considered one of the important sources of enteric infections in humans. The use of probiotics, which can help to improve the natural defense of animals against pathogenic bacteria, is an alternative and effective approach to antibiotic administration for livestock to reduce bacterial contamination. In vitro experiments showed that Enterococcus faecium, Pediococcus acidilactici, Lactobacillus salivarius, and Lactobacillus reuteri isolated from healthy chicken gut inhibited the growth of C. jejuni. To demonstrate this effect in vivo, 1-d-old broiler chicks received 2 mg/bird per day of a multispecies probiotic product via the drinking water. Controls received no probiotic treatment, and all chicks were infected with C. jejuni orally. Results showed that the cecal colonization by C. jejuni was significantly reduced by probiotic treatment at both 8 and 15 d postchallenge. To confirm this effect, in a second in vivo experiment, 1-d-old broiler chicks received the same dose of the same probiotic via the drinking water and controls received no probiotic, and all chicks were infected with C. jejuni orally. Similarly, probiotic treatment reduced (P=0.001) cecal colonization by C. jejuni at both 8 and 15 d postchallenge. The results of our in vivo experiments conclude that probiotic administration reduced the colonization of C. jejuni in broiler chickens.

Application of medium-chain fatty acids in drinking water increases Campylobacter jejuni colonization threshold in broiler chicks

Campylobacteriosis is the most reported bacterial-mediated gastroenteritic disease in many developed countries. Broiler chickens are a natural host for Campylobacter spp., and contaminated poultry meat products are a major source for transmitting pathogenic Campylobacter strains to humans. Currently, no intervention measure efficiently and effectively controls this pathogen in poultry flocks. Medium-chain fatty acids (caproic, caprylic, capric, and lauric acids) show a marked anti-Campylobacter activity in vitro. However, in recent trials using our in vivo models, administering these acids to the feed of broiler chicks neither prevented nor reduced cecal C. jejuni colonization in broilers. In the present study, we examined whether a drinking water application of medium-chain fatty acids might be more effective in combating Campylobacter colonization in poultry. Although Campylobacter colonization and transmission was not reduced, we demonstrate that adding an emulsion of a mixture of caproic, caprylic, capric, and lauric acids to the drinking water of broiler chicks reduces their colonization susceptibility and prevents C. jejuni survival in drinking water. Thus, the merit of water applications of medium-chain fatty acids is the reduction of the probability of Campylobacter entry into and transmission throughout a flock.

Effect of thymol or diphenyliodonium chloride on performance, gut fermentation characteristics, and campylobacter colonization in growing swine.

Food producing animals can be reservoirs of Campylobacter, a leading bacterial cause of human foodborne illness. Campylobacter spp. utilize amino acids as major carbon and energy substrates, a process that can be inhibited by thymol and diphenyliodonium chloride (DIC). To determine the effect of these potential additives on feed intake, live weight gain, and gut Campylobacter levels, growing pigs were fed standard grower diets supplemented with or without 0.0067 or 0.0201% thymol or 0.00014 or 0.00042% DIC in a replicated study design. Diets were offered twice daily for 7 days, during which time daily feed intake (mean ± SEM, 2.39 ± 0.06 kg day(-1)) and daily gain (0.62 ± 0.04 kg day(-1)) were unaffected (P > 0.05) by treatment. Pigs treated with DIC but not thymol tended to have lower rectal Campylobacter levels (P ∼ 0.07) (5.2 versus 4.2 and 4.4 log CFU g(-1) rectal contents for controls and 0.00014% DIC and 0.00042% DIC, respectively; SEM ∼ 0.26). However, DIC or thymol treatments did not affect (P > 0.05) ileal or cecal Campylobacter (1.6 ± 0.17 and 4.5 ± 0.26 log CFU g(-1), respectively), cecal total culturable anaerobes (9.8 ± 0.10 log CFU g(-1)), or accumulations of major fermentation end products within collected gut contents. These results suggest that thymol and DIC were appreciably absorbed, degraded, or otherwise made unavailable in the proximal alimentary tract and that encapsulation technologies will likely be needed to deliver effective concentrations of these compounds to the lower gut to achieve in vivo reductions of Campylobacter.

Colonization properties ofCampylobacter jejuniin chickens

Campylobacter is the most common bacterial food-borne pathogen worldwide. Poultry and specifically chicken and raw chicken meat is the main source for human Campylobacter infection. Whilst being colonized by Campylobacter spp. chicken in contrast to human, do scarcely develop pathological lesions. The immune mechanisms controlling Campylobacter colonization and infection in chickens are still not clear. Previous studies and our investigations indicate that the ability to colonize the chicken varies significantly not only between Campylobacter strains but also depending on the original source of the infecting isolate. The data provides circumstantial evidence that early immune mechanisms in the gut may play an important role in the fate of Campylobacter in the host.

Toward integrative genomics study of genetic resistance to Salmonella and Campylobacter intestinal colonization in fowl.

Salmonella enterica serotypes Enteritidis and Typhimurium and Campylobacter jejuni are responsible for most cases of food poisoning in Europe. These bacteria do not cause severe disease symptoms in chicken, but they are easily propagated by symptomless chicken carriers which cannot be easily isolated. This animal tolerance is detrimental to food safety. In this particular case, increasing animal's resistance is not sufficient, since some animals considered as resistant are able to carry bacteria during several weeks without displaying disease symptoms. We review studies aimed at evaluating the resistance of chicken to Salmonella and Campylobacter intestinal colonization, either a few days or several weeks after infection. While studies of the genetic control of Campylobacter colonization are only beginning, mostly due to technical difficulties in infection protocols, genetic studies of Salmonella colonization have been conducted for now more than 20 years. They have initially reported an estimation of the genetic parameters associated with resistance to Salmonella colonization and are now aimed at identifying the genomic regions controlling variation of this trait in experimental lines and commercial populations. With the advent of high-throughput genomics, we are closer than ever to identify the true genes controlling resistance to Enterobacteria colonization in chicken. The comparison of genes involved in early resistance to intestinal colonization with genes controlling resistance to bacteria persistence several weeks after infection (i.e., carrier-state) should soon highlight the differences between the molecular mechanisms underlying those two distinct phenotypes. It will also be highly interesting to compare the genes or genomic regions controlling Campylobacter and Salmonella, in order to evaluate the feasibility of a selection conducted on both bacteria simultaneously.

Prevalence and Antimicrobial Susceptibility ofCampylobacterin Broiler Flocks in Japan

Campylobacter was isolated from 67 (47.2%) of 142 broiler flocks between September 2009 and February 2010. The prevalence of Campylobacter in broiler flocks was significantly lower during January and February than it was from September to December. Campylobacter colonization was more common in flocks that were not provided with a disinfected water supply, which was consistent with the findings of a previous study. The prevalence of antimicrobial drug-resistant Campylobacter spp. was investigated, and the minimum inhibitory concentrations of eight antimicrobial agents were determined for 122 Campylobacter jejuni isolates and 46 Campylobacter coli isolates from broiler flocks between 2007 and 2010. In this study, 29.5% (36/122) of C.jejuni isolates and 41.3% (19/46) of C.coli isolates were resistant to enrofloxacin (ERFX), whereas all isolates were susceptible to erythromycin. Furthermore, the ERFX-resistant isolates were tested for susceptibility to other classes of antimicrobial agents, and 55.6% (20/36) of ERFX-resistant C.jejuni isolates and 47.4% (9/19) of ERFX-resistant C.coli isolates were resistant to at least one of aminobenzyl penicillin, dihydrostreptomycin and oxytetracycline. To avoid an impact of antimicrobial drug-resistant Campylobacter spp. on the efficacy of antimicrobial treatment for human campylobacteriosis, prudent use of antimicrobial agents is a requisite. The use of antimicrobial agents should be accompanied by various approaches such as prevention of Campylobacter colonization in broiler flocks with the aim of lowering the occurrence of Campylobacter infection in humans.

Development and stability of bacteriocin resistance in Campylobacter spp.

Several bacteriocins (BCNs) that were identified from chicken commensal bacteria dramatically reduced Campylobacter colonization in poultry and are being directed toward on-farm control of this important foodborne human pathogen. A recent study has shown that BCN resistance in Campylobacter jejuni is very difficult to develop in vitro. In this study, in vivo development and stability of BCN resistance in Campylobacter was examined. Chickens infected with Camp. jejuni NCTC 11168 were treated with BCN E-760 at the dose of 5 mg kg(-1) body weight day(-1) via oral gavages for three consecutive days, which selected BCN-resistant (BCN(r)) mutants in the treated birds. However, all the in vivo-selected mutants only displayed low levels of resistance to BCN (MIC = 2-8 mg l(-1)) when compared to parent strain (MIC = 0.5 mg l(-1)). Inactivation of CmeABC efflux pump of the BCN(r) mutants led to increased susceptibility to BCN (8-32 fold MIC reduction). Three different BCN(r) Campylobacter strains (in vitro- or in vivo-derived) were examined for the stability of BCN resistance using both in vitro and in vivo systems. The low level of BCN resistance in these strains was not stable in vitro or in vivo in the absence of BCN selection pressure. Usage of BCN E-760 only selected low-level BCN(r) Camp. jejuni mutants in vivo, and the low-level BCN resistance was not stable in vitro and in vivo. The study provides helpful information for risk assessment of the future practical application of the anti-Campylobacter BCNs in animals.

Biosecurity-based interventions and strategies to reduce Campylobacter spp. on poultry farms.

The prevention and control of Campylobacter colonization of poultry flocks are important public health strategies for the control of human campylobacteriosis. A critical review of the literature on interventions to control Campylobacter in poultry on farms was undertaken using a systematic approach. Although the focus of the review was on aspects appropriate to the United Kingdom poultry industry, the research reviewed was gathered from worldwide literature. Multiple electronic databases were employed to search the literature, in any language, from 1980 to September 2008. A primary set of 4,316 references was identified and scanned, using specific agreed-upon criteria, to select relevant references related to biosecurity-based interventions. The final library comprised 173 references. Identification of the sources of Campylobacter in poultry flocks was required to inform the development of targeted interventions to disrupt transmission routes. The approach used generally involved risk factor-based surveys related to culture-positive or -negative flocks, usually combined with a structured questionnaire. In addition, some studies, either in combination or independently, undertook intervention trials. Many of these studies were compromised by poor design, sampling, and statistical analysis. The evidence for each potential source and route of transmission on the poultry farm was reviewed critically, and the options for intervention were considered. The review concluded that, in most instances, biosecurity on conventional broiler farms can be enhanced and this should contribute to the reduction of flock colonization. However, complementary, non-biosecurity-based approaches will also be required in the future to maximize the reduction of Campylobacter-positive flocks at the farm level.

The cinnamon-oil ingredient trans-cinnamaldehyde fails to target Campylobacter jejuni strain KC 40 in the broiler chicken cecum despite marked in vitro activity.

Campylobacter jejuni is the most common bacterial cause of diarrheal disease in humans worldwide, with poultry products being a major source. Therefore, strategies to decrease Campylobacter colonization during primary production might aid in reducing the number of human campylobacteriosis cases. Several plant-derived compounds have been reported to possess anti-Campylobacter properties in vitro, so they could be promising candidates to reduce Campylobacter colonization in broiler chickens. To test this hypothesis, selected plant-derived antimicrobials (caffeic, gallic, protocatechuic, and vanillic acids, epigallocatechin gallate, trans-cinnamaldehyde, and thymol) were screened for anti-Campylobacter activity by determining MICs and setting up time-kill curves for C. jejuni strain KC 40. These experiments revealed marked antibacterial activity, especially for the cinnamon oil ingredient trans-cinnamaldehyde (CIN). This compound was tested in a broiler chick seeder model; it was added to the feed in coated form at an effective concentration of 0.3 % from day-of-hatch for the entire 22-day duration of the experiment. At 14 days of age, one-third of the birds were inoculated with C. jejuni strain KC 40 and served as seeders. CIN was not able to reduce cecal Campylobacter colonization in this model, which was confirmed in a cecal loop experiment. Despite CIN concentrations much higher than the MIC, C. jejuni numbers were not reduced compared with those in nontreated ceca at 2 and 24 h after injection. In conclusion, this study shows a marked discrepancy between in vitro and in vivo activity of CIN against C. jejuni strain KC 40.

Effects of climatic elements on Campylobacter-contaminated chicken products in Japan

Japanese weather data for areas that produced Campylobacter spp.-positive chicken products were compared with those for areas producing negative samples. Regarding samples produced during the period of rising temperature (spring and summer), the mean weekly air temperatures for Campylobacter-positive samples were higher than those for negative samples for the period of the week in which the samples were purchased (18.7 °C vs. 13.1 °C, P = 0.006) to a 12-week lag (12 weeks before purchasing samples; 7.9 °C vs. 3.4 °C, P = 0.009). Significant differences in weekly mean minimum humidity and sunshine duration per day were also observed for 1- and 2-week lag periods. We postulated that the high air temperature, high humidity and short duration of sunshine for the chicken-rearing period increased Campylobacter colonization in chickens during the period of rising temperature. Consequently, the number of Campylobacter-contaminated chicken products on the market in Japan may fluctuate because of the climatic conditions to which reared chickens are exposed.

Isolation of Campylobacter from Circulating Blood of Commercial Broilers

Campylobacter spp. are present in organs and tissues of broiler chickens but the dissemination route is unclear. The aim of the current study was to determine Campylobacter prevalence within circulating blood of commercial broilers. Broilers were acquired from 19 flocks originating from three commercial poultry processing companies. Using aseptic blood collection techniques, 5 ml of circulating blood was collected from each bird and the sample analyzed for Campylobacter. The Campylobacter colonization status of each bird was determined by aseptically sampling and analyzing the ceca. Campylobacter was recovered from 58% (11/19) of flocks sampled. From the 248 total birds sampled, 12% and 46% of the birds had Campylobacter in the blood and ceca, respectively. This study documents Campylobacter prevalence in the circulating blood of commercially raised broilers. Campylobacter presence in the circulatory system may indicate the path used by the organism for rapid dissemination to organs and tissues. From a processing viewpoint, Campylobacter presence in circulating blood of market-age broilers may increase the likelihood of cross-contamination between birds during slaughter.

Molecular tracking, through processing, of Campylobacter strains colonizing broiler flocks.

Many of the poultry flocks produced in the United Kingdom are colonized with Campylobacter, and the intensive nature of poultry processing usually results in contaminated carcasses. In this study, a previously reported molecular oligonucleotide probe method was used to track a specific flock-colonizing strain(s) on broiler carcasses during processing in two United Kingdom commercial poultry processing plants. Five Campylobacter-positive flocks were sampled at four points along the processing line, postbleed, postpluck, prechill, and postchill, and two Campylobacter-negative flocks processed immediately after positive flocks were sampled prechill. flaA was sequenced from Campylobacter strains isolated from these flocks, and strain-specific probes were synthesized. Skin and cecal samples were plated onto selective agar to give individual colonies, which were transferred onto membranes. These were then hybridized with the strain- and genus-specific probes. For all the 5 positive flocks, there was a significant reduction in campylobacters postbleed compared to postpluck but no subsequent fall on sampling pre- and postchill, and the strain(s) predominating on the carcasses throughout processing came from the flock being processed. This indicates that strains from the abattoir environment were not a significant cause of carcass contamination in flocks with well-established campylobacter colonization. However, negative flocks that were preceded by positive flocks were contaminated by strains that did not generally originate from the predominating strains recovered from the ceca of the previous positive flocks. This suggests that the abattoir environment has a significant role in the contamination of carcasses from negative but not fully colonized flocks.

Functional Characterization of a Lipoprotein-Encoding Operon in Campylobacter jejuni

BackgroundBacterial lipoproteins have important functions in bacterial pathogenesis and physiology. In Campylobacter jejuni, a major foodborne pathogen causing gastroenteritis in humans, the majority of lipoproteins have not been functionally characterized. Previously, we showed by DNA microarray that CmeR, a transcriptional regulator repressing the expression of the multidrug efflux pump CmeABC, modulates the expression of a three-gene operon (cj0089, cj0090, and cj0091) encoding a cluster of lipoproteins in C. jejuni.Methodology/Principal FindingsIn this work, we characterized the function and regulation of the cj0089-cj0090-cj0091 operon. In contrast to the repression of cmeABC, CmeR activates the expression of the lipoprotein genes and the regulation is confirmed by immunoblotting using anti-Cj0089 and anti-Cj0091 antibodies. Gel mobility shift assay showed that CmeR directly binds to the promoter of the lipoprotein operon, but the binding is much weaker compared with the promoter of cmeABC. Analysis of different cellular fractions indicated that Cj0089 was associated with the inner membrane, while Cj0091 was located on the outer membrane. Inactivation of cj0091, but not cj0089, significantly reduced the adherence of C. jejuni to INT 407 cells in vitro, indicating that Cj0091 has a function in adherence. When inoculated into chickens, the Cj0091 mutant also showed a defect in early colonization of the intestinal tract, suggesting that Cj0091 contributes to Campylobacter colonization in vivo. It was also shown that Cj0091 was produced and immunogenic in chickens that were naturally infected by C. jejuni.Conclusion/SignificanceThese results indicate that the lipoprotein operon is subject to direct regulation by CmeR and that Cj0091 functions as an adhesion mechanism in C. jejuni and contributes to Campylobacter colonization of the intestinal tract in animal hosts.

Influence of production system on the rate of onset of Campylobacter colonization in chicken flocks reared extensively in the United Kingdom

1. Because thermophilic Campylobacter spp. are common in chicken flocks reared extensively, cross-sectional and longitudinal studies were carried out on organic and free-range farms to determine the onset of colonisation (lag phase) and likely sources of flock infection. 2. For 14 organic and 14 free range flocks, there was a difference in lag phases, with the former being colonized at a mean of 14·1 d in comparison with 31·6 d for the latter. Whereas most free-range flocks became colonized when released on to pasture, those reared organically were usually colonized at the housed brooding stage. 3. Further study of organic flocks on three farms over 7 successive crop cycles confirmed that colonisation was strongly influenced by the prevailing husbandry conditions and was not a consequence of the length of the rearing period. 4. Molecular epidemiological investigations on a farm showing the shortest lag phase, using PFGE typing with two different restriction enzymes (SmaI and KpnI) and flaA SVR sequence typing, revealed that potential sources of colonisation for organic chickens were already present on the farm at the time of chick placement. Such sources included the ante area of the brooding house, surrounding pasture and other livestock being kept on the farm. 5. Overall, the study demonstrated that, under UK conditions, the prevalence of colonisation was greater in extensive flocks (95–100%) than it was for conventional broilers (55%), similar to the situation in other countries, but all three management systems showed comparable levels of caecal carriage in positive birds (log10/g 6·2–6·7).

Water administration of the medium-chain fatty acid caprylic acid produced variable efficacy against enteric Campylobacter colonization in broilers1,2

Campylobacter is one of the most common causes of foodborne illness, and poultry are considered a primary source of Campylobacter infections. Caprylic acid, an 8-carbon fatty acid, has been shown in previous studies to reduce enteric cecal Campylobacter concentrations in poultry when administered in the feed. For greater ease of application for producers, a water-soluble form of caprylic acid, sodium octanoate, was evaluated for efficacy against enteric Campylobacter. The first trial consisted of 70 birds in 7 groups (n = 10 chicks/group): an untreated control and 6 other groups that were challenged with Campylobacter at d 3 and that received 0, 0.175, 0.35, 0.7, 1.4, or 2.8% water-soluble caprylic acid in water 3 d before necropsy at d 14. The second trial consisted of 80 birds in 8 groups (n = 10 chicks/group): an untreated negative control and 7 other groups, all of which were challenged with Campylobacter at d 3 and received 0, 0.044, 0.088, 0.175, 0.35, 0.7, or 1.4% water-soluble caprylic acid for 3 d before necropsy at d 14. In trial 1, only the 0.175% dose caused a reduction in cecal Campylobacter counts in comparison with the positive control (approximately a 3-log reduction). In trial 2, no treatment reduced Campylobacter counts compared with the positive control. Unlike the efficacy of caprylic acid in feed, treatment with caprylic acid in water had an inconsistent effect on intestinal Campylobacter counts.

Risk Factors forCampylobacterColonization in Broiler Flocks in Japan

The present study was conducted to estimate the prevalence of and to identify the risk factors for Campylobacter colonization in broiler flocks in Japan. Campylobacter colonization status in flock was evaluated by culturing pooled caecal excrement from 124 broiler flocks. Potential exposure to risk factors was evaluated with a questionnaire for the broiler producers. Odds ratios (ORs) were calculated using a multivariable logistic regression analysis. The prevalence of Campylobacter-positive flocks was 43.5% (upper and lower limits of 95% confidence interval (CI(95%) ): 34.8, 52.3). Multivariable logistic regression model identified two variables as risk factors for Campylobacter colonization. The ORs of Campylobacter colonization were higher in flocks in western Japan (OR=2.68; CI(95%) : 1.04, 6.91) than in eastern Japan, and in flocks supplied with undisinfected drinking water (OR=7.41; CI(95%) : 3.11, 17.66) than in those supplied with disinfected drinking water. These findings indicate that water may play an important role in Campylobacter colonization in broiler flocks in Japan and the use of disinfected water may reduce the risk of Campylobacter colonization.

Comparison of Campylobacter Levels in Crops and Ceca of Broilers at Slaughter

A considerable fraction of the poultry carcasses becomes contaminated with Campylobacter by cross-contamination from the digestive tract of colonized broilers at slaughter. Campylobacter in the crop may serve as a possible source of cross-contamination, because the crop may contain high numbers of Campylobacter and is more likely to rupture during the slaughtering process than intestines. In this study, the correlation between Campylobacter colonization levels in crop and cecum was assessed in 48 broilers of 31 days of age. In addition, the effect of drinking water supplemented with 0.2% volatile fatty acid (VFA) on these Campylobacter colonization levels was studied. No correlation between crop and cecal colonization levels was found (p = 0.09; P = 0.71), indicating that future studies on cross-contamination should include an examination of not only cecal colonization levels but also crop colonization levels. Supplementation of drinking water with VFA did not result in a significant reduction of colonization levels in either the crop (P = 0.50) or the ceca (P = 0.92), indicating that this is not an effective measure to reduce cross-contamination at slaughter.

Analysis of the baseline survey on the prevalence of Campylobacter in broiler batches and of Campylobacter and Salmonella on broiler carcasses, in the EU, 2008 - Part B: Analysis of factors associated with Campylobacter colonisation of broiler batches and

Analysis of the baseline survey on the prevalence of Campylobacter in broiler batches and of Campylobacter and Salmonella on broiler carcasses, in the EU, 2008 - Part B: Analysis of factors associated with Campylobacter colonisation of broiler batches and

Intestinal mucus protects Campylobacter jejuni in the ceca of colonized broiler chickens against the bactericidal effects of medium-chain fatty acids

Campylobacter jejuni is the most common cause of bacterial-mediated diarrheal disease worldwide. Because poultry and poultry products are a major source of C. jejuni infections in humans, efforts should be taken to develop strategies to decrease Campylobacter shedding during primary production. For this purpose, the efficacy of medium-chain fatty acids (MCFA) as feed additives to control C. jejuni colonization in broiler chickens was analyzed. First, the antimicrobial activity of the MCFA caproic, caprylic, and capric acid on C. jejuni was evaluated in vitro. Minimal inhibitory concentrations were 0.25 mM for caproic and 0.5 mM for caprylic and capric acids at pH 6.0 and 4 mM for all 3 compounds at pH 7.5. Time-kill curves revealed strong bactericidal properties of the tested compounds toward C. jejuni at pH 6.0. Concentrations as low as 4 mM caprylic and capric acids and 16 mM caproic acid killed all bacteria within 24 h. Capric acid had the highest activity, with concentrations of 4 mM killing all bacteria within the hour. Together these data show a profound bactericidal, dose-dependent activity of the tested MCFA toward C. jejuni in vitro. For this reason, the effect of these 3 MCFA on C. jejuni was evaluated in vivo. The addition of any of the acids to the feed, from 3 d before euthanization, was not capable of reducing cecal Campylobacter colonization in 27-d-old broilers experimentally infected with C. jejuni at 15 d of age. Using a cecal loop model, sodium caprate was not able to reduce cecal Campylobacter counts. When time-kill curves were conducted in the presence of chick intestinal mucus, capric acid was less active against C. jejuni. At 4 mM, all bacteria were killed only after 24 h. Thus, despite the marked bactericidal effect of MCFA in vitro, supplementing these acids to the feed does not reduce cecal Campylobacter colonization in broiler chickens under the applied test conditions, probably due to the protective effect of the mucus layer.