Campylobacter-positive Flocks Research Articles

Rapid detection of Campylobacter spp. in chickens before slaughter

Campylobacter continues to be the number one cause of bacterial gastroenteritis in Europe. Poultry, and especially broiler chickens, is considered an important reservoir for Campylobacter spp. Poultry producers prioritize to identify and reduce the number of Campylobacter contaminated chicken flocks by tightening biosecurity and mitigation actions at slaughter. Campylobacter-positive flocks must therefore be identified as close to slaughter as possible, and rapid detection methods are needed. Here we evaluated the applicability, sensitivity, and specificity of four commercially available rapid methods to detect Campylobacter in naturally contaminated chicken cecal droppings on-farm before slaughter against an established qPCR method. The Biofire® FilmArray® Gastrointestinal Panel assay, the VIDAS Campylobacter assay, the Singlepath® Campylobacter test, and OptiGenes' Genie Campylobacter isothermal DNA amplification were assessed in a pilot-study. The OptiGenes’ Genie Campylobacter isothermal DNA amplification was also tested under field conditions. The Biofire® FilmArray® showed superior sensitivity and specificity compared to the three other rapid tests but had a lower throughput and a higher cost. While the VIDAS Campylobacter, Singlepath® Campylobacter and the isothermal DNA amplification were affordable, their unsatisfactory sensitivity (10%–71%) left these unsuitable to monitor Campylobacter carriage in chickens. An additional finding of this study is that 38% of flocks positive for Campylobacter at slaughter became contaminated during the last week of rearing. Therefore, increased efforts to develop suitable methods to detect Campylobacter rapidly and reliably in chickens close to slaughter are needed.

A Multicenter Proposal for a Fast Tool To Screen Biosecure Chicken Flocks for the Foodborne Pathogen Campylobacter.

The present multicenter study aimed at assessing the performance of air sampling as a novel method for monitoring Campylobacter in biosecure poultry farms. We compared, using a harmonized procedure, the bacteriological isolation protocol (ISO 10272-1:2017) and a real-time PCR method used on air filter samples. Air samples and boot swabs were collected from 62 biosecure flocks from five European countries during the summer of 2019. For air filters, the frequency of PCR-positive findings was significantly higher (n = 36; 58%) than that obtained with the cultivation methods (P < 0.01; standardized residuals). The cultivation protocols (one with Bolton enrichment and one with Preston enrichment) were comparable to each other but returned fewer positive samples (0 to 8%). The association between type of sample and frequency of PCR-positive findings was statistically confirmed (P < 0.01; Fisher´s exact test), although no culture-positive air filters were detected using direct plating. For the boot swabs, the highest number of positive samples were detected after enrichment in Preston broth (n = 23; 37%), followed by direct plating after homogenization in Preston (n = 21; 34%) or Bolton broth (n = 20; 32%). It is noteworthy that the flocks in Norway, a country known to have low Campylobacter prevalence in biosecure chicken flocks, tested negative for Campylobacter by the new sensitive approach. In conclusion, air sampling combined with real-time PCR is proposed as a multipurpose, low-cost, and convenient screening method that can be up to four times faster and four times more sensitive than the current boot-swab testing scheme used for screening biosecure chicken production.IMPORTANCECampylobacter bacteria are the cause of the vast majority of registered cases of foodborne illness in the industrialized world. In fact, the bacteria caused 246,571 registered cases of foodborne illness in 2018, which equates to 70% of all registered cases in Europe that year. An important tool to prevent campylobacters from making people sick is good data on where in the food chain the bacterium is present. The present study reports a new test method that quadruples the likelihood of identifying campylobacter-positive chicken flocks. It is important to identify campylobacter-positive flocks before they arrive at the slaughterhouse, because negative flocks can be slaughtered first in order to avoid cross-contamination along the production line.

Identification of Transmission Routes of Campylobacter and On-Farm Measures to Reduce Campylobacter in Chicken.

An in-depth analysis was performed on Swedish broiler producers that had delivered chickens with Campylobacter to slaughter over several years, in order to identify possible transmission routes and formulate effective measures to prevent chickens being colonized with Campylobacter. Between 2017 and 2019, 626 samples were collected at farm level and Campylobacter was isolated from 133 (21.2%). All C. jejuni and C. coli isolated from these samples were whole-genome sequenced, together with isolates from the corresponding cecum samples at slaughter (n = 256). Core genome multi-locus sequence typing (cgMLST) analysis, using schemes consisting of 1140 and 529 genes for C. jejuni and C. coli, respectively, revealed that nearby cattle, contaminated drinking water, water ponds, transport crates, and parent flocks were potential reservoirs of Campylobacter. A novel feature compared with previous studies is that measures were implemented and tested during the work. These contributed to a nationwide decrease in Campylobacter-positive flocks from 15.4% in 2016 to 4.6% in 2019, which is the lowest ever rate in Sweden. To conclude, there are different sources and routes of Campylobacter transmission to chickens from different broiler producers, and individual measures must be taken by each producer to prevent Campylobacter colonization of chickens.

Quantification of the Campylobacter contamination on broiler carcasses during the slaughter of Campylobacter positive flocks in semi-industrialized slaughterhouses

Campylobacter contamination of broiler carcasses has been little studied in semi-industrialized slaughterhouses in developing countries, where several steps are carried out manually or with limited technology. In this study, we performed quantification of the Campylobacter contamination on carcasses at four steps in the slaughter process in three Ecuadorian slaughterhouses. Therefore, 15 Campylobacter positive batches were sampled in three commercial slaughterhouses. For every batch, caecal content and five samples of breast skin were taken and examined for Campylobacter counts at the following steps: after plucking, after evisceration, after final washing and after water chilling. Slaughterhouse C was the only slaughterhouse in which Campylobacter counts increased significantly after evisceration. No significant differences were found between counts after evisceration and after final washing (P > 0.05). In all slaughterhouses, a significant reduction of Campylobacter counts (0.11 to 2.55 log10 CFU/g) was found after the chilling step. The presence of chlorine in the chilling water was associated with the highest reduction in Campylobacter counts on the carcasses. A high variability of Campylobacter counts was found within and between batches slaughtered in the same slaughterhouse. Campylobacter counts in caecal content samples were not correlated with counts on carcasses after plucking nor after evisceration.

Prevalence and types of Campylobacter on poultry farms and in their direct environment.

To study whether broiler and layer farms contribute to the environmental Campylobacter load, environmental matrices at or close to farms, and caecal material from chickens, were examined. Similarity between Campylobacter from poultry and environment was tested based on species identification and Multilocus Sequence Typing. Campylobacter prevalence in caecal samples was 97% at layer farms (n = 5), and 93% at broiler farms with Campylobacter-positive flocks (n = 2/3). Campylobacter prevalence in environmental samples was 24% at layer farms, and 29% at broiler farms with Campylobacter-positive flocks. Campylobacter was detected in soil and surface water, not in dust and flies. Campylobacter prevalence in adjacent and remote surface waters was not significantly (P > 0.1) different. Detected species were C. coli (52%), C. jejuni (40%) and C. lari (7%) in layers, and C. jejuni (100%) in broilers. Identical sequence types (STs) were detected in caecal material and soil. A deviating species distribution in surface water adjacent to farms indicated a high background level of environmental Campylobacter. STs from layer farms were completely deviant from surface water STs. The occasional detection of identical STs in broilers, wastewater at broiler farms and surface water in the farm environment suggested a possible contribution of broiler farms to the aquatic environmental Campylobacter load.

Climatic factors and prevalence of Campylobacter in commercial broiler flocks in Thailand

Campylobacter are bacteria associated with human foodborne disease worldwide. Poultry and poultry products are generally considered as a main source of these organisms. Compared to temperate zones, baseline information on Campylobacter in tropical regions is limited. Thus, the objectives of the present study were 1) to determine the prevalence of Campylobacter in Thai broiler flocks and 2) to investigate the association between climatic factors (i.e., rainfall, ambient temperature, and relative humidity) and Campylobacter colonization status of broiler flocks in Thailand. A total of 442 commercial broiler flocks reared in the central and northeastern regions of Thailand during 2012 to 2014 were investigated. Campylobacter positive status was identified in 252 examined flocks (57.01%; 95% CI 52.39 to 61.63%). Prevalence of Campylobacter in the northeastern region (54.46%; 95% CI 44.76 to 63.83%) was slightly lower than that of the central region (57.77%; 95% CI 52.47 to 62.90%). More than 65% of Campylobacter positive flocks in the central and northeastern regions had within-flock prevalence higher than 75%. Generalized estimating equations (GEE) revealed that the increased rainfall and relative humidity were associated with the increase of Campylobacter colonization in broiler flocks (P ≤ 0.05), while no relationship between ambient temperature and Campylobacter colonization status was identified.

Compliance/non-compliance with biosecurity rules specified in the Danish Quality Assurance system (KIK) and Campylobacter- positive broiler flocks 2012 and 2013

One source for Campylobacter jejuni infections in humans could be consumption of broiler meat. Transmission of Campylobacter into broiler houses/flocks occurs via many routes. A number of biosecurity rules is specified in the Quality Assurance System in Danish Chicken Production (KIK) — for which the broiler producers annually are audited for compliance with, by bureau Veritas. Multivariable logistic regression models were used to investigated the association between Compliance/non-compliance with biosecurity rules and Campylobacter-positive flocks - on KIK data from 2012 and 2013. Month and before after audit period were also included in the models. KIK rules important to comply with were: no vegetation around houses, closed systems for feed storage and distribution, and division between clean and unclean zones within broiler houses. A Campylobacter-reducing effect was observed of audit visits (in itself), indicating that there is more focus on compliance with KIK at the time of an audit visit, and that adequate daily biosecurity behavior is important.

Sensitivity of Direct Culture, Enrichment and PCR for Detection of Campylobacter jejuni and C.coli in Broiler Flocks at Slaughter.

Broiler chicken flocks are a significant source of Campylobacter jejuni and Campylobacter coli that result in the major public health problem of campylobacteriosis. Accurate estimates of the prevalence of both C.coli and C.jejuni in flocks would enhance epidemiological understanding, risk assessment and control options. This study combined results from a panel of 10 detection tests (direct culture, enrichment and PCR) on caecal samples from flocks at slaughter. A parallel interpretation approach was used to determine the presence of Campylobacter spp. and for C.jejuni and C.coli individually. The sample was considered positive if at least one method detected the target and this interpretation was taken to represent a 'proxy gold standard' for detection in the absence of a gold standard reference test. The sensitivity of each individual method to detect Campylobacter spp., C.jejuni and C.coli was then estimated relative to the proxy gold standard. Enrichment in adapted Exeter broth (deficient in polymyxin B) with a resuscitation step was 100% sensitive, whilst direct culture on modified charcoal cefoperazone deoxycholate agar (mCCDA) was highly sensitive (97.9%). Enrichment methods using Preston broth and Bolton broth were significantly less sensitive. Enrichment in Exeter broth promoted the recovery of C.jejuni, whilst enrichment in Bolton broth favoured C.coli. A RT-PCR detection test could identify 80% of flocks that were co-colonised with both species. This study found that 76.3% (n=127) of flocks were colonised with Campylobacter spp. The majority (95.9%) of Campylobacter-positive flocks were colonised with C.jejuni; however, approximately one-third of positive flocks were simultaneously colonised with both C.jejuni and C.coli. The findings highlight the impact of different detection methodologies on the accuracy of the estimated incidence of both C.jejuni and C.coli entering the abattoir within broiler flocks and the associated public health risks.

Use of Direct LAMP Screening of Broiler Fecal Samples for Campylobacter jejuni and Campylobacter coli in the Positive Flock Identification Strategy.

Rapid identification of Campylobacter-positive flocks before slaughter, following freezing and heat treatment for the Campylobacter-positive carcasses at the slaughterhouses is an effective control strategy against foodborne campylobacteriosis. We evaluated a loop-mediated isothermal amplification (LAMP) assay for the direct screening of naturally contaminated chicken cloacal swabs for C. jejuni/C. coli to compare this assay with conventional quantitative culture methods. In a comparison study of 165 broilers, the LAMP assay showed 82.8% (48/58 by conventional culture) sensitivity, 100% (107/107) specificity, 100% (48/48) positive predictive value (PPV), and 91.5% (107/117) negative predictive value (NPV). In a comparison of 55 flocks, LAMP showed 90.5% (19/21) sensitivity, 100% (34/34) specificity, 100% (19/19) PPV, and 94.4% (34/36) NPV. In the cumulative total of 28 farm-level comparisons, LAMP showed 100% (12/12) sensitivity, 100% (16/16) specificity, 100% (12/12) PPV, and 100% (16/16) NPV. The LAMP assay required less than 90 min from the arrival of the fecal samples to final results in the laboratory. This suggests that the LAMP assay will facilitate the identification of C. jejuni/C. coli-positive broiler flocks at the farm level or in slaughterhouses before slaughtering, which would make it an effective tool in preventing the spread of Campylobacter contamination.

食鳥処理場におけるカンピロバクター交差汚染状況

In this study, we investigated Campylobacter prevalence in chicken fecal samples and cross-contamination of chicken carcass surface samples at a slaughterhouse, with an aim toward the production of Campylobacter-free chicken meat. Twenty-four broiler flocks comprising a total of 120 chickens were examined. C. jejuni were isolated in fecal samples from 34 chickens (28.3%) in 12 flocks, and C. jejuni and C. coli were from 5 chickens (4.2%) in a flock, respectively. A total of 13 Campylobacter-positive flocks and 11 Campylobacter-free flocks existed in this research. Immediately after all Campylobacter-free flocks had been slaughtered, no Campylobacter could be detected from the chicken carcass surfaces. However, all slaughtered flocks, including those that were initially Campylobacter-free, were later found to have been cross-contaminated by Campylobacter-positive flocks slaughtered on the same day. Our results indicate that preventing cross-contamination from Campylobacter-positive flocks is a crucial consideration for chicken slaughterhouse to produce Campylobacter-free chicken meat.

Risk factors for Campylobacter colonization in Danish broiler flocks, 2010 to 2011

The objectives of the two studies presented were to estimate the prevalence of Campylobacter-positive farms and flocks and to acquire updated knowledge about risk factors for the introduction of Campylobacter in Danish broiler flocks. In the first study, from September 2010 to September 2011, there were 25 Danish broiler farms visited, and a questionnaire was filled in by a veterinarian/consultant. In the second study, a similar questionnaire was distributed electronically to all Danish broiler farmers (n = 164) that were on record with an email address in the Quality Assurance System in the Danish Broiler Production (KIK) database. House- and flock-specific data collected in the surveys were supplemented with information obtained from the KIK database. Data obtained from the two studies were analyzed separately by logistic regression analysis. In both models, the dependent variable was “Campylobacter flock status (positive/negative),” which was based on real-time PCR testing of fecal material from the floor of each broiler house that had been collected preslaughter using a pair of tube gauze “socks.” This material was pooled into one sample. Of the 25 farms visited, 17 had delivered Campylobacter-positive flocks during the study period, and eight farms had no Campylobacter-positive flocks. Moreover, the flock prevalence of Campylobacter was 17% (n = 418). Data obtained from the electronically distributed survey revealed that 63% (n = 71) of the farms were Campylobacter-positive. Further, the flock prevalence of Campylobacter was 14% (n = 1,286). The multivariable models from the two sets of data identified the following statistically significant risk factors: summer vs. winter; if the previous flock in the house was positive for Campylobacter vs. if the previous flock in the house was negative; and litter delivered into the house close to the time of arrival of new chickens vs. storing litter on the farm. Furthermore, the data showed that a vertically based ventilation system (where most of the air is taken into the house through chimneys) constituted a higher risk than a horizontally based system (where the air is taken in through openings in the side walls).

Quantitative estimation of Campylobacter cross-contamination in carcasses and chicken products at an abattoir

This study aimed to investigate Campylobacter contamination in carcasses and chicken products derived from a Campylobacter-negative flock when the flock is slaughtered immediately after a Campylobacter-positive flock. The first 2 flocks slaughtered on 10 different dates were investigated at an abattoir. Eighteen of the 20 flocks tested were positive for Campylobacter. A Campylobacter-negative flock was slaughtered immediately after a Campylobacter-positive flock on only 1 of the 10 slaughter dates. In this case, Campylobacter was detected in the carcasses and chicken products originating from the Campylobacter-negative flock, and all the flaA genotypes of these isolates were identical to those present in the caecal contents, carcasses, and chicken products from the Campylobacter-positive flock. The Campylobacter concentrations in the products originating from the Campylobacter-negative flock were: close to the enumeration limit (1.7 log10 cfu/carcass) in the carcass samples; and below the enumeration limit (2.0 log10 cfu/g) in the liver samples. The mean Campylobacter concentrations in the carcasses and liver products originating from the 18 Campylobacter-positive flocks were 3.8 log10 cfu/carcass and 2.6 log10 cfu/g, respectively. While 91% (246/270) of chicken products originating from Campylobacter-positive flocks were positive for Campylobacter, chicken products originating from the remaining Campylobacter-negative flock were free from Campylobacter cross-contamination by slaughter prior to a Campylobacter-positive flock. These results prove that slaughtering Campylobacter-negative flocks does not introduce Campylobacter into the abattoirs and indicate that although carcasses and chicken products originating from the Campylobacter-negative flock were cross-contaminated with Campylobacter from the Campylobacter-positive flock slaughtered immediately before, the Campylobacter contamination levels were lower than those in carcasses and chicken products from Campylobacter-positive flocks. Based on these findings, the reduction of Campylobacter prevalence in broiler flocks should be taken as an effective control measure for preventing introduction of Campylobacter into abattoirs and consequently for reducing Campylobacter prevalence in chicken products in addition to the good hygienic practice at abattoirs and logistic slaughter.

Survival of Campylobacter jejuni in naturally and artificially contaminated laying hen feces

Infected laying hens regularly excrete large amounts of Campylobacter jejuni with their feces, which represent a reservoir of infection within the flock and for animals in the region. However, the knowledge about survival times of C. jejuni in these feces is still scarce. Therefore, orienting laboratory experiments were carried out under controlled conditions to estimate the survival times of C. jejuni both in artificially and naturally contaminated laying hen feces. In 6 different laying hen flocks (3 Campylobacter-free and 3 Campylobacter-positive flocks), fresh excreta were randomly collected and pooled in 20-g samples per flock. In the laboratory, each of the 3 pooled samples from the Campylobacter-free barns were homogenized and mixed with 10 mL of a freshly prepared C. jejuni suspension (3 × 108 cfu/mL). The other 3 samples were homogenized only. The 6 samples were stored at 20 ± 1°C and 40 to 60% RH in 2 different incubators. Specimens of 2 g were taken from all 6 samples 1 h after storage and daily at the same time during the next 10 consecutive days and investigated on culturable C. jejuni. The survival times of culturable C. jejuni ranged from 72 to 96 h in artificially inoculated feces and varied from 120 to 144 h in naturally colonized flocks. The flaA typing by RFLP confirmed that the isolates from the artificially contaminated feces were identical with the added strain. A total of 5 different flaA types were identified from the naturally contaminated feces, and survival of these isolates was dependent on flaA type. The demonstrated survival times indicate that contaminated fresh feces are an important reservoir of C. jejuni, representing a permanent source of infection over at least 6 d after excretion. It shows the considerable potential of fresh feces in transmitting the agent within and between flocks during that period. This 6-d span should be considered when poultry manure is applied to land as organic fertilizer.

Rapid monitoring of Campylobacter in high-shedding flocks for targeted disease control.

Broilers excreting Campylobacter spp. at high levels (>7 log CFU/g of feces) were described in the Dutch Campylobacter Risk Management and Assessment project as an important source of carcass contamination. The researchers concluded that the risk of infection to humans could be economically and efficiently minimized by eliminating these flocks from fresh poultry meat chains. In the present study, we evaluated a simple and rapid gold-labeled immunosorbent assay (GLISA) for the identification of Campylobacter spp. in flocks shedding high levels of the pathogen. Results were obtained within 2 h. Pooled samples from 102 of the 114 Campylobacter-positive flocks produced positive results, resulting in a test sensitivity of 89.5% (95% confidence interval, 82.6 to 94.2%) and a test specificity of 94.5% (86.7 to 98.2%). Given a GLISA detection limit of 7.3 log CFU/g of feces, nearly all Campylobacter-positive flocks were identified as "high shedders." Therefore, reduction of the incidence of Campylobacter infections by elimination of high-shedding flocks from fresh meat production is an unrealistic approach. Under the constraints given, a reduction in the incidence of Campylobacter spp. in Austria will require either improved hygiene or an intensive carcass decontamination strategy in fresh meat production facilities.

Campylobacter Cross‐Contamination of Chicken Products at an Abattoir

Consumption of raw or undercooked poultry products contaminated with Campylobacter has been identified as a risk factor for human campylobacteriosis. We determined whether slaughtering of Campylobacter-positive flocks was associated with contamination of chicken products derived from Campylobacter-negative flocks slaughtered at the same abattoir. The presence of Campylobacter was investigated in 22 broiler farms 1 week prior to slaughter and in one abattoir on nine separate slaughter days. A total of 600 bulk packed chicken products were tested, with 198 (33.0%) of the products found to be Campylobacter positive. Of the 350 chicken products originating from Campylobacter-positive flocks, 180 (51.1%) were contaminated with the bacteria. In contrast, only 18 (7.2%) of 250 chicken products derived from Campylobacter-negative flocks were contaminated. In 14 of these 18 products, the Campylobacter isolates were identical to isolates obtained from the flock slaughtered immediately prior to the Campylobacter-negative flock. Notably, on 4/6 slaughter days, Campylobacter-negative flocks were slaughtered prior to the positive flocks, and Campylobacter was absent from all chicken products originating from the negative flocks. These results suggest that implementation of logistic slaughter (where Campylobacter-negative flocks are slaughter first) significantly decreases the prevalence of Campylobacter-positive chicken products.

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.

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.

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.

Risk factors associated with the presence of Campylobacter-positive broiler flocks in Sweden

Approximately 40% of Swedish broiler producers deliver Campylobacter-negative broilers in 90–100% of their flocks, showing that it is possible to produce Campylobacter-free broilers in Sweden. This study investigated risk factors associated with the presence of Campylobacter-positive flocks at Swedish broiler producers. A total of 37 producers, with 90 broiler houses including 144 compartments, participated in the study. An on-farm interview was performed to collect information on potential risk factors for Campylobacter infection in broilers, with questions about farmcharacteristics such as the environment around the farm and broiler houses, design of the broiler houses and on-farm management practices. Negative binomial regression models were used to assess the statistical significance of risk factors associated with the within-farm number of Campylobacter-positive flocks (the outcome). Campylobacter is transmitted in broiler flocks due to multiple factors and several potential sources, illustrating the complexity of Campylobacter epidemiology in broilers. Factors significantly associated with increased proportion of Campylobacter-positive flocks were the presence of other livestock on the farm, or the presence of cattle, swine, poultry or fur animals within 1 km of the farm. Poor or average general tidiness were associated with increased proportion of Campylobacter-positive flocks, but decreased if split slaughter was seldom or never applied or if farm workers changed footwear twice or three times instead of once before entering the broiler house.

The effects of Campylobacter numbers in caeca on the contamination of broiler carcasses with Campylobacter

For the presence and number of Campylobacter, 18 broiler flocks were sampled over a period of 18 months. A total of 70% of the flocks were positive for Campylobacter, with higher prevalence found in summer and autumn, compared to winter and spring. Positive flocks showed contamination rates above 90%, in negative flocks this was lower, mostly below 50%. The enumeration showed a decrease in Campylobacter during processing of positive flocks. The numbers were highest in carcasses after scalding/defeathering (mean 5.9 log 10 cfu/carcass) and dropped by 0.7 log 10 cfu/carcass after chilling. A positive correlation was observed between the number of Campylobacter present in the caeca and the number of bacteria present on carcasses and cut products. When a negative flock was slaughtered after Campylobacter positive flocks, the number of positive samples was higher compared to the case when a negative flock had been slaughtered previously. C. jejuni was isolated from 73.6% of the poultry samples.