Molecular characterization of the diversity of Campylobacter spp. isolates collected from a poultry slaughterhouse: analysis of cross-contamination

Prevalence, Antimicrobial Resistance, and Molecular Characterization of Campylobacter Isolated from Broilers and Broiler Meat Raised without Antibiotics

Campylobacter is one of the main bacterial pathogens that cause campylobacteriosis in the United States. Poultry is considered a major reservoir for the transmission of Campylobacter to humans. This study aimed to determine the prevalence and molecular characteristics of Campylobacter in the no-antibiotics-ever (NAE) broilers. A total of 414 samples were collected, among which 160 retail chicken samples were purchased from grocery stores and 254 samples were collected from broiler farms located in Mississippi State. The overall prevalence of Campylobacter was 25.4%, and a significantly higher prevalence was observed in retail chicken than in the farm samples (36.3% versus 18.5%; P < 0.0001), respectively. The prevalence of Campylobacter was not different (P = 0.263) between conventional retail (40.0%) and NAE (31.4%) retail chicken. Campylobacter jejuni was the predominant species among the positive isolates, accounting for 78.1%. Among the 82 C. jejuni isolates, 52.4% of the isolates carried the gyrA gene followed by the tet(O) gene (14.6%), whereas toxin-producing genes cdtA, cdtB, and cdtC were carried by 43.9%, 46.3%, and 43.9%, respectively. However, none of these virulence genes were detected in C. jejuni isolated from litter samples. Among tested C. jejuni, 13.6% of the isolates were multidrug resistant. The highest resistance was observed against nalidixic acid (49.2%), followed by tetracycline (23.7%). Our study suggests that the prevalence of Campylobacter was higher in retail meat samples than in environmental samples obtained from farms, and there was no difference in Campylobacter prevalence among conventional and NAE retail chicken. IMPORTANCE The FDA antibiotic withdrawal policy has led to a shift in the production system, from conventional antibiotics fed birds to no antibiotics ever (NAE) raised birds. However, the impact of this shift to NAE on the prevalence and characteristics of Campylobacter has not been studied on the farm or in retail chicken meats. The objective of this study was to determine the current prevalence of Campylobacter and the distribution of their antimicrobial resistance and virulence genes in NAE-raised broilers. The findings of this study will help the industry to take necessary action to develop effective mitigation strategies for reducing Campylobacter contamination in NAE broilers.

Prevalence of and Risk Factors for Campylobacter spp. Colonization of Broiler Chicken Flocks in Greece

The prevalence and risk factors for Campylobacter spp. colonization of broiler flocks and broiler carcass contamination in Greek slaughterhouses were investigated. Over a 14-month period, a pool of 10 ceca and 5 neck skin samples from chicken carcasses were collected from each of 142 batches of broiler flocks slaughtered in 3 different slaughterhouses. Information on potential risk factors for Campylobacter infection in broilers was collected by an on-farm interview and linked according to the Campylobacter contamination status of broiler flocks and differences in farm characteristics and management practices identified from questionnaires. Campylobacter spp. was isolated from 73.94% and 70.42% of ceca (95% CI 65.92-80.94) and carcasses (95% CI 62.19-77.78), respectively. A significant correlation (p < 0.001) between the presence of Campylobacter spp. in broiler ceca and contamination of carcasses was found, suggesting the spread of the microorganism on the skin of carcasses during the slaughtering procedure. A multiple logistic regression showed the disinfection of the poultry house being conducted by unskilled personnel (odds ratio [OR] ¼ = 3.983) as a significant risk factor (p < 0.05) and the use of straw litter as bedding material (OR ¼ = 0.170) and closure of windows during the intervals of production cycles (OR ¼ = 0.396) as significant protective factors (p < 0.05) for broiler flock contamination. These results are important and help further the understanding of the epidemiology of Campylobacter spp. derived from poultry in Greece.

Campylobacter contamination of broilers: the role of transport and slaughterhouse

Campylobacter is one of the most important causative agents of foodborne illnesses worldwide. The poultry reservoir is the main source of Campylobacter. Within the broiler production chain, campylobacters can only multiply in the chicken's intestinal tract. Intervention at farm level to reduce Campylobacter is thus preferred, but despite extensive study, no highly effective solutions have been found to combat Campylobacter at farm level. Slaughterhouses are experiencing great pressure to deliver carcasses with low Campylobacter contamination even when they receive and slaughter Campylobacter colonized flocks. Since 2018, a process hygiene criterion (EU 2017/1495) with the critical limit of <1000 cfu/g neck skin has been implemented in EU Member States based on the calculation done at the time of the study that human campylobacteriosis cases could be halved if all carcasses would comply with a criterion of <1000 cfu/g neck skin. This review covers Campylobacter contamination of broiler carcasses from transport through the different slaughter steps. Possible intervention methods during slaughter are discussed with a focus on the European situation, where chemicals are not allowed to disinfect carcasses.

In vitro efficacy of potentiated egg yolk powder against Campylobacter jejuni does not correlate with in vitro efficacy

Campylobacter jejuni is a zoonotic agent responsible for the foodborne gastroenteritis campylobacteriosis. Control of C. jejuni load in the poultry primary production is recognized as an avenue to reduce human exposure to the pathogen. As for now, no commercially applicable control methods exist at the farm. Several studies tested egg yolk powders, potentiated or not against C. jejuni, as feed additives for chicken and suggested that the quantity and quality of the antibodies presence in the yolk are determinant factors for the full success of this approach. Unfortunately, data from these studies inconsistently showed a reduction of cecal C. jejuni carriage. Our first goal wwas to characterize (quantification by ELISA, agglutination test, bacterial antigen recognition profiles by Western blot, bactericidal effect by serum killing assays and C. jejuni mobility by soft agar migation) the antibodies extracted from egg yolk powders originating from different egg production protocols. Secondly, these powders were microencapsulated and recharacterized. Finally the protected powders were tested as a feed additive to destabilize C. jejuni colonization in an in vivo assay. Despite the in vitro results indicating the ability of the egg yolk powders to recognize Campylobacter and potentially alter its colonization of the chicken caecum, these results were not confirmed in the in vivo trial despite that specific caecal IgY directed toward Campylobacter were detected in the groups receiving the protected powders. More research is needed on Campylobacter in order to effectively control this pathogen at the farm.

Prevalence, genotyping and risk factors of thermophilic Campylobacter spreading in organic turkey farms in Germany

BACKGROUND

The need for organic food of animal origin has increased rapidly in recent years. However, effects of organic animal husbandry on food safety have not been rigorously tested especially in meat turkey flocks. This study provides for the first time an overview on the prevalence and genetic diversity of Campylobacter species (spp.) in five organic meat turkey farms located in different regions in Germany, as well as on potential risk factors of bacterial spreading. Thirty cloacal swabs as well as water samples and darkling beetles were collected from each flock and examined for the presence of Campylobacter by conventional and molecular biological methods. The isolates were genotyped by flaA-RFLP.

RESULTS

Campylobacter spp. were detected in cloacal swabs in all 5 turkey flocks with prevalence ranged from 90.0 to 100 %. 13 cloacal swabs collected from birds in farm III and IV were harboured mixed population of thermophilic campylobacters. In total, from 158 Campylobacter isolated from turkeys 89 (56.33 %) were identified as C. coli and 69 (43.76 %) as C. jejuni. Three Campylobacter (2 C. jejuni and 1 C. coli) were detected in drinkers of two farms and 3 C. coli were isolated from darkling beetles of one farm. No Campylobacter were isolated from main water tanks. flaA-RFLP assay showed that turkey farms can harbour more than one genotype. In a single turkey two different genotypes could be detected. The genotypes of campylobacters isolated from water samples or beetles were identical with those isolated from turkeys. No effect was found of some environmental parameters [ammonia concentration (NH3), carbon dioxide concentration (CO2), relative humidity (RH) and air temperature)] on Campylobacter prevalence in organic turkey farms. Additionally, drinking water and darkling beetles might be considered as risk factors for the spreading of Campylobacter in turkey flocks.

CONCLUSIONS

This study highlights the high prevalence and genotypic diversity of Campylobacter spp. isolated from organic turkey flocks. Further research is needed to assess other potential risk factors responsible for bacteria spreading in order to mitigate the spread of Campylobacter in organic turkey flocks by improving biosecurity control measures.

Survival in water of Campylobacter jejuni strains isolated from the slaughterhouse

Campylobacter jejuni cause gastroenteritis in humans. The main transmission vector is the consumption or handling of contaminated chicken meat, since chicken can be colonized asymptomatically by C. jejuni. However, water has been implicated as the transmission vector in a few outbreaks. One possibility is the contamination of water effluent by C. jejuni originating from chicken farm. The ability of C. jejuni to be transmitted by water would be closely associated to its ability to survive in water. Therefore, in this study, we have evaluated the ability of reference strains and chicken-isolated strains to survive in water. Defined water media were used, since the composition of tap water is variable. We showed that some isolates survive better than others in defined freshwater (Fraquil) and that the survival was affected by temperature and the concentration of NaCl. By comparing the ability of C. jejuni to survive in water with other phenotypic properties previously tested, we showed that the ability to survive in water was negatively correlated with autoagglutination. Our data showed that not all chicken isolates have the same ability to survive in water, which is probably due to difference in genetic content.

Poultry flocks as a source of Campylobacter contamination of broiler carcasses

Campylobacterinfection is the leading foodborne bacterial gastroenteritis worldwide and the bacteria are frequently isolated from the intestines of chickens. The broiler meat contamination withC. jejuniorC. colimay occur during slaughter processing. The aim of the study was to investigate the prevalence ofCampylobacterin poultry flocks and the corresponding broiler carcasses in 15 districts (voivodeships) all over Poland. A total of 128 samples from broiler flocks and the corresponding carcasses were collected between February 2011 and April 2013. TheCampylobacterisolation and species identification were performed according to ISO 10272-1 standard and with PCR. It was found that 112 flock (96.5%) were contaminated with campylobacters, eitherC. jejuni(77 samples; 68.7%) orC. coli(35 flocks; 31.3%). Analysis of the corresponding chicken carcasses tested after chilling revealed that 77 out of 128 (60.2%) samples were positive forCampylobacter, eitherC. jejuni(58; 75.3%) orC. coli(19; 24.7%). Most of the carcasses were contaminated with the sameCampylobacterspecies as identified in the corresponding flock before slaughter. As tested by PCR, out of the 77 crops withC. jejuni58 were positive for the same bacterial species. On the other hand, out of the remaining 35 flocks infected withC. coli, only 19 corresponding carcass samples were contaminated withC. coli. In three cases in the slaughtered flocksC. jejuniwas identified but in the same carcassesC. coliwas found. The opposite findings (flock positive forC. colibut the corresponding carcasses contaminated withC. jejuni) were seen in six voivodeships. It was also observed that several carcass samples were negative forC. jejuniandC. colialthough the original flocks wereCampylobacter-positive before slaughter (total 36 of the 77 samples; 46.7%). On the other hand, some carcasses were contaminated withCampylobacteralthough the flocks were negative for these bacteria (9 samples; 11.7%) which may also be due to internal contamination during slaughter of broilers.

Comparison of Campylobacter contamination levels on chicken carcasses between modern and traditional types of slaughtering facilities in Malaysia

A total of 360 samples including fresh fecal droppings, neck skins, and swab samples was collected from 24 broiler flocks and processed by 12 modern processing plants in 6 states in Malaysia. Ninety samples from 10 traditional wet markets located in the same states as modern processing plants were also collected. Microbiological isolation for Campylobacter was performed following ISO 10272-1:2006 (E). The overall rate of contamination for Campylobacter in modern processing plants and in traditional wet markets was 61.1% (220/360) and 85.6% (77/90), respectively. Campylobacter jejuni was detected as the majority with approximately 70% for both facilities. In the modern processing plants, the contamination rate for Campylobacter gradually declined from 80.6% before the inside-outside washing to 62.5% after inside-outside washing and to 38.9% after the post chilling step. The contamination rate for Campylobacter from processed chicken neck skin in traditional wet markets (93.3%) was significantly (P<0.01) higher than in modern processing plants (38.9%).

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.

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 (log(10)/g 6·2-6·7).

Campylobacter contamination of broiler caeca and carcasses at the slaughterhouse and correlation with Salmonella contamination

In order to estimate the prevalence of Campylobacter spp. and Salmonella spp. on broiler chicken carcasses and the prevalence of Campylobacter spp. in caeca, 58 French slaughterhouses were investigated in 2008. Enumeration of Campylobacter spp. was also performed in order to study the relation between caeca and carcass contamination. A pool of 10 caeca and one carcass were collected from 425 different batches over a 12-month period in 2008. Salmonella was isolated on 32 carcasses leading to a prevalence of 7.5% ([5.0-10.0](95%CI)). The prevalence of Campylobacter was 77.2% ([73.2-81.2](95%CI)) in caeca and 87.5% ([84.4-90.7](95%CI)) on carcasses. No significant correlation was found between Campylobacter and Salmonella. Positive values of Campylobacter were normally distributed and the average level was 8.05 log(10) cfu/g ([7.94-8.16](95%CI)) in caeca and 2.39 cfu/g ([2.30-2.48](95%CI)) on carcasses. A positive correlation (r = 0.59) was found between the mean of Campylobacter in caeca and on carcasses (p < 0.001). Thus, carcasses from batches with Campylobacter-positive caeca had significantly (p < 0.001) higher numbers of Campylobacter per gram than batches with negative caeca. These results show that Campylobacter can be present in both matrices and reduction in caeca could be a possible way to reduce the amount of bacteria on carcasses. Of the 2504 identifications performed, 3 species of Campylobacter (Campylobacter jejuni, Campylobacter coli and Campylobacter lari) were identified. The main species recovered were C. jejuni and C. coli, which were isolated in 55.3% and 44.5% of positive samples, respectively. These two species were equally represented in caeca but C. jejuni was the most frequently isolated on carcasses with 57.1% and 42.5% of positive carcasses for C. jejuni and C. coli, respectively. This study underlines that target a reduction of Campylobacter on final products requires a decrease of contamination in caeca.

Campylobacter genotypes from poultry transportation crates indicate a source of contamination and transmission

AIMS

Crates used to transport live poultry can be contaminated with Campylobacter, despite periodic sanitization, and are potential vectors for transmission between flocks. We investigated the microbial contamination of standard and silver ion containing crates in normal use and the genetic structure of associated Campylobacter populations.

METHODS AND RESULTS

Bacteria from crates were enumerated by appropriate culture techniques, and multilocus sequence typing (MLST) was used to determine the genetic structure of Campylobacters isolated from standard and silver ion containing crates. Compared to standard crates, counts of bacteria, including Campylobacter, were consistently lower on silver ion containing crates throughout the decontamination process. In total, 16 different sequence types were identified from 89 Campylobacter jejuni isolates from crates. These were attributed to putative source population (chicken, cattle, sheep, the environment, wild bird) using the population genetic model, structure. Most (89%) were attributed to chicken, with 22% attribution to live chicken and 78% to retail poultry meat. MLST revealed a progressive shift in allele frequencies through the crate decontamination process. Campylobacter on crates survived for at least 3 h after sanitization, a period of time equivalent to the journey from the processing plant to the majority of farms in the catchment, showing the potential for involvement of crates in transmission.

CONCLUSIONS

Inclusion of a silver ion biocide in poultry transportation crates to levels demonstrating acceptable antibacterial activity in vitro reduces the level of bacterial contamination during normal crate use compared to standard crates. Molecular analysis of Campylobacter isolates indicated a change in genetic structure of the population with respect to the poultry-processing plant sanitization practice.

SIGNIFICANCE AND IMPACT OF THE STUDY

The application of a sustainable antimicrobial to components of poultry processing may contribute to reducing the levels of Campylobacter circulating in poultry.

Phage-displayed peptides selected for binding to Campylobacter jejuni are antimicrobial

In developed countries, Campylobacter jejuni is a leading cause of zoonotic bacterial gastroenteritis in humans with chicken meat implicated as a source of infection. Campylobacter jejuni colonises the lower gastrointestinal tract of poultry and during processing is spread from the gastrointestinal tract onto the surface of dressed carcasses. Controlling or eliminating C.jejuni on-farm is considered to be one of the best strategies for reducing human infection. Molecules on the cell surface of C.jejuni interact with the host to facilitate its colonisation and persistence in the gastrointestinal tract of poultry. We used a subtractive phage-display protocol to affinity select for peptides binding to the cell surface of a poultry isolate of C.jejuni with the aim of finding peptides that could be used to control this microorganism in chickens. In total, 27 phage peptides, representing 11 unique clones, were found to inhibit the growth of C.jejuni by up to 99.9% in vitro. One clone was bactericidal, reducing the viability of C.jejuni by 87% in vitro. The phage peptides were highly specific. They completely inhibited the growth of two of the four poultry isolates of C.jejuni tested with no activity detected towards other Gram-negative and Gram-positive bacteria.

Quantitative and qualitative evaluation of Campylobacter spp. contamination of turkey cecal contents and carcasses during and following the slaughtering process

The present study aimed to document quantitatively and qualitatively the contamination by thermotolerant Campylobacter spp. of turkey samples during slaughtering. Four Campylobacter-positive turkey flocks were investigated at the slaughterhouse at three different stages: evisceration (cecal content), after carcass rinses but before chilling (neck skin), and after breast meat cut (meat). In each case, the studied flock was slaughtered first thing in the morning any given day of the week. The efficiency of cleaning and disinfecting operations was examined in the facility prior to processing the studied flock. For each flock, 90 samples were collected from cecal contents, neck skins, and meat pieces and checked quantitatively and qualitatively for Campylobacter. Identification of Campylobacter species was determined by PCR, and genetic patterns were determined by pulsed-field gel electrophoresis. Campylobacter contamination levels of ceca range from 2 to more than 7 Log CFU/g, while those of neck skin range from 0.5 to 3.5 Log CFU/g and those of meat range from 0.1 to 1.9 Log CFU/g. These differences in Campylobacter counts were not associated with a modification of Campylobacter species ratio; however, in the Campylobacter jejuni population, four genetic groups identified from the ceca were not recovered during slaughtering operations and two other genetic groups were only detected after chilling at the cutting stage of the breast meat. The present study suggests that the slaughtering process did not affect Campylobacter species populations; however, it might have influenced the strain population. Finally, the Campylobacter populations found on breast meat were similar to those isolated from the digestive tract of the birds.

Comparison of Campylobacter populations isolated from a free-range broiler flock before and after slaughter

Relatively little is known about the Campylobacter genotypes colonizing extensively reared broiler flocks and their survival through the slaughter process, despite the increasing demand for free-range and organic products by the consumer. Campylobacter isolates from a free-range boiler flock, sampled before and after slaughter, were genotyped by MLST (multilocus sequence typing) and sequence analysis of the flaA short variable region (SVR). The Campylobacter genotypes isolated before and after slaughter were diverse, with up to five sequence types (STs) (seven-locus allelic profiles resulting from MLST) identified per live bird, up to eight STs identified per carcass and 31 STs identified in all. The majority (72.0%) of isolates sampled from carcasses post-slaughter were indistinguishable from those isolated from the live flock before slaughter by ST and flaA SVR type, however, sampling 'on-farm' failed to capture all of the diversity seen post-slaughter. There were statistically significant increases in the genetic diversity of Campylobacter (p=0.005) and the proportion of C. coli (p=0.002), with some evidence for differential survival of genotypes contaminating the end product. C. coli genotypes isolated after slaughter were more similar to those from free-range and organic meat products sampled nationally, than from the live flock sampled previously. This study demonstrated the utility of MLST in detecting genetic diversity before and after the slaughter process.

Real-time PCR approach for detection of environmental sources of Campylobacter strains colonizing broiler flocks

Reducing colonization of poultry flocks by Campylobacter spp. is a key strategy in the control and prevention human campylobacteriosis. Horizontal transmission of campylobacters, from in and around the farm, is the presumed route of flock colonization. However, the identification and prioritization of sources are confounded by the ubiquitous nature of these organisms in the environment, their poor rates of recovery by standard culture methods, and the need for cost-effective and timely methods for strain-specific comparison. A real-time PCR screening test for the strain-specific detection of campylobacters in environmental samples has been developed to address this issue. To enable this approach, fluorescently labeled PCR oligonucleotide probes suitable for a LightCycler-based assay were designed to match a highly variable DNA segment within the flaA short variable region (SVR) of Campylobacter jejuni or C. coli. The capacity of such probes to provide strain-specific tools was investigated by using bacterial cultures and spiked and naturally contaminated poultry fecal and environmental samples. The sensitivity of two representative probes was estimated, by using two different C. jejuni strains, to be 1.3 x 10(2) to 3.7 x 10(2) CFU/ml in bacterial cultures and 6.6 x 10(2) CFU/ml in spiked fecal samples. The specificity of the SVR for C. jejuni and C. coli was confirmed by using a panel of strains comprising other Campylobacter species and naturally contaminated samples. The approach was field tested by sampling the environment and feces of chickens of two adjacently located poultry houses on a conventional broiler farm throughout the life of one flock. All environmental samples were enriched for 2 days, and then DNA was prepared and stored. Where feasible, campylobacter isolates were also recovered and stored for subsequent testing. A strain-specific probe based on the SVR of the strain isolated from the first positive chicken fecal sample was developed. This probe was then used to screen the stored environmental samples by real-time PCR. Pulsed-field gel electrophoresis was used to compare recovered environmental and fecal isolates to assess the specificity of the method. The results established the proof of principle that strain-specific probes, based on the SVR of flaA, can identify a flock-colonizing strain in DNA preparations from enriched environmental cultures. Such a novel strategy provides the opportunity to investigate the epidemiology of campylobacters in poultry flocks and allows targeted biosecurity interventions to be developed. The strategy may also have wider applications for the tracking of specific campylobacter strains in heavily contaminated environments.

Pasture intake improves the performance and meat sensory attributes of free-range broilers

Free-range chickens are assumed to consume low to moderate levels of pasture, although the effects of forage intake in broiler performance and poultry meat quality remain to be established. In addition, despite cellulases and hemicellulases being widely used as feed supplements to improve the nutritive value of cereal-based diets for fast-growing broilers, the potential interest of these biocatalysts in the production of free-range chicken is yet to be established. In this study, broilers of the RedBro Cou Nu x RedBro M genotype were fed a cereal-based diet in portable floorless pens located either on a rainfed subterranean clover (Trifolium subterraneum) pasture or on an irrigated white clover (Trifolium repens) pasture. Control birds were maintained at the same site in identical pens but with no access to pastures. The importance of pasture intake and enzyme supplementation in the performance and meat sensory properties of the free-range chicken from d 28 to 56 was investigated. The results revealed that although cellulase and hemicellulase supplementation had no impact on broiler performance (P > 0.05), birds foraging on legume-based pastures reached significantly greater final BW. The data suggest that the improvement in broiler performance results from increased intake of the cereal-based feed rather than from an improvement in the efficiency of nutrient utilization per se. Interestingly, although the intake of the subterranean clover pasture had no impact on the tenderness, juiciness, and flavor of broiler meat, members of a 30-person consumer panel classified the meat from grazing broilers with greater scores for overall appreciation. Together, the results suggest that pasture intake promotes bird performance while contributing to the production of broiler meat with preferred sensory attributes.

Campylobacter jejuni colonization and transmission in broiler chickens: a modelling perspective

Campylobacter jejuni is one of the most common causes of acute enteritis in the developed world. The consumption of contaminated poultry, where C. jejuni is believed to be a commensal organism, is a major risk factor. However, the dynamics of this colonization process in commercially reared chickens is still poorly understood. Quantification of these dynamics of infection at an individual level is vital to understand transmission within populations and formulate new control strategies. There are multiple potential routes of introduction of C. jejuni into a commercial flock. Introduction is followed by a rapid increase in environmental levels of C. jejuni and the level of colonization of individual broilers. Recent experimental and epidemiological evidence suggest that the celerity of this process could be masking a complex pattern of colonization and extinction of bacterial strains within individual hosts. Despite the rapidity of colonization, experimental transmission studies exhibit a highly variable and unexplained delay time in the initial stages of the process. We review past models of transmission of C. jejuni in broilers and consider simple modifications, motivated by the plausible biological mechanisms of clearance and latency, which could account for this delay. We show how simple mathematical models can be used to guide the focus of experimental studies by providing testable predictions based on our hypotheses. We conclude by suggesting that competition experiments could be used to further understand the dynamics and mechanisms underlying the colonization process. The population models for such competition processes have been extensively studied in other ecological and evolutionary contexts. However, C. jejuni can potentially adapt phenotypically through phase variation in gene expression, leading to unification of ecological and evolutionary time-scales. For a theoretician, the colonization dynamics of C. jejuni offer an experimental system to explore these 'phylodynamics', the synthesis of population dynamics and evolutionary biology.

Evaluation of logistic processing to reduce cross-contamination of commercial broiler carcasses with Campylobacter spp

Cross-contamination of broiler carcasses with Campylobacter is a large problem in food production. Here, we investigated whether the contamination of broilers carcasses from Campylobacter-negative flocks can be avoided by logistic scheduling during processing. For this purpose, fecal samples were collected from several commercial broiler flocks and enumerated for Campylobacter spp. Based on enumeration results, flocks were categorized as Campylobacter negative or Campylobacter positive. The schedule of processing included the testing of Campylobacter-positive flocks before or after the testing of Campylobacter-negative flocks. During processing, flocks were also sampled for Campylobacter spp. before and after chilling. Campylobacter strains were identified with multiplex PCR and analyzed for relatedness with pulsed-field gel electrophoresis. Our results show that Campylobacter-negative flocks were indeed contaminated with Campylobacter strains originating from previously processed Campylobacter-positive flocks. Campylobacter isolates collected from carcasses originating from different farms processed on the same day showed similar pulsed-field gel electrophoresis patterns, confirming cross-contamination. These findings suggest that a simple logistic processing schedule can preserve the Campylobacter-negative status of broiler carcasses and result in products with enhanced food safety.

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.

Prevalence and risk factors for Salmonella and Campylobacter spp. carcass contamination in broiler chickens slaughtered in Quebec, Canada

An observational study was conducted to estimate prevalence and risk factors for Salmonella and Campylobacter spp. carcass contamination in broiler chickens. Eighty-two lots were sampled in four slaughterhouses located in the province of Québec, Canada, over a 10-month period. Carcass contamination was evaluated by the carcass rinse technique for about 30 birds per lot. Exposure to potential risk factors was evaluated based on data from questionnaires, meteorology, and cecal cultures. Multivariable binomial negative regression models were used for risk factor analysis at the lot level. The prevalence of Salmonella-positive carcasses was 21.2% (95% confidence interval: 15.7 to 26.7%). Significant risk factors (P < 0.05) associated with a higher proportion of positive carcasses within lots were Salmonella-positive cecal culture, low rainfall during transportation to the slaughterhouse, temperature of > or = 0 degree C during transportation to the slaughterhouse, and a > or = 4-h waiting period in shipping crates before slaughtering. The prevalence of Campylobacter-positive carcasses was 35.8% (95% confidence interval: 27.1 to 44.5%). Lots containing birds with Campylobacter-positive cecal culture results, lots of birds that were slaughtered at the end of the week, and lots with at least 20% of birds with digestive contents detected in the jejunum at time of slaughtering had a significantly higher proportion (P < 0.05) of contaminated carcasses. These results support the importance of preharvest control measures implemented during rearing to reduce contamination of the final product. Weather during transportation to slaughter and the day of the week that birds were slaughtered also were associated with carcass contamination; further studies are needed to determine the underlying mechanisms by which these factors influence carcass contamination.

Prevalence and numbers of Campylobacter on broiler carcasses collected at rehang and postchill in 20 U.S. processing plants

Campylobacter is a human pathogen associated with chicken and chicken meat products. This study was designed to examine the prevalence and number of Campylobacter on broiler chicken carcasses in commercial processing plants in the United States. Carcass samples were collected from each of 20 U.S. plants four times, roughly approximating the four seasons of 2005. At each plant on each sample day, 10 carcasses were collected at rehang (prior to evisceration), and 10 carcasses from the same flock were collected postchill. A total of 800 carcasses were collected at rehang and another 800 were collected postchill. All carcasses were subjected to a whole-carcass rinse, and the rinse diluent was cultured for Campylobacter. The overall mean number of Campylobacter detected on carcasses at rehang was 2.66 log CFU per ml of carcass rinse. In each plant, the Campylobacter numbers were significantly reduced by broiler processing; the mean concentration after chill was 0.43 log CFU/ml. Overall prevalence was also reduced by processing from a mean of > or =30 of 40 carcasses at rehang to > or =14 of 40 carcasses at postchill. Seven different on-line reprocessing techniques were applied in the test plants, and all techniques resulted in <1 log CFU/ml after chilling. Use of a chlorinated carcass wash before evisceration did not affect the postchill Campylobacter numbers. However, use of chlorine in the chill tank was related to lower numbers on postchill carcasses. Overall, U.S. commercial poultry slaughter operations are successful in significantly lowering the prevalence and number of Campylobacter on broiler carcasses during processing.

Prevalence and risk factors for Salmonella and Campylobacter spp. carcass contamination in turkeys slaughtered in Quebec, Canada

An observational study was conducted to estimate prevalence and risk factors for carcass contamination by Salmonella and Campylobacter spp. in 60 lots of turkey slaughtered over 10 months in the province of Quebec, Canada. Carcass contamination was evaluated by the carcass rinse technique for about 30 birds per lot. Exposure to potential risk factors was evaluated with questionnaires, meteorological data, and cecal cultures. Multivariable binomial negative regression models were used for risk factor analysis. Prevalence of Salmonella-positive carcasses was 31.2% (95% confidence interval, 22.8 to 39.5%). Variables positively associated (P < or = 0.05) with the proportion of lot-positive carcasses were > or =0.5% of carcass condemnation due to various pathologies, cecal samples positive for Salmonella, low wind speed during transportation, closure of lateral curtains of truck during transportation, and slaughtering on a weekday other than Monday. When only Salmonella-positive cecal culture lots were considered, the proportion of carcasses positive for Salmonella was significantly higher in lots exposed to a >5 degrees C outside temperature variation during transportation, slaughtered on a weekday other than Monday, and in which > or = 4% of carcasses had visible contamination. Prevalence of Campylobacter-positive carcasses was 36.9% (95% confidence interval, 27.6 to 46.3%). The proportion of positive carcasses was significantly higher in lots with Campylobacter-positive cecal cultures and lots undergoing > or =2 h of transit to slaughterhouse. For lots with Campylobacter-positive cecal cultures, variables significantly associated with an increased incidence of carcass contamination were de4% of carcasses with visible contamination, crating for > or =8 h before slaughtering, and no antimicrobials used during rearing.

Predominant strains of thermophilic Campylobacter spp. in a German poultry slaughterhouse

Campylobacter causes bacterial diarrhoea in man and is a common foodborne pathogen, that has been associated mainly with poultry carcasses and processed poultry products as well as with drinking water. Genotyping of Campylobacter spp. from poultry was done in order to prove if predominant stable strains in the food chain are present. The influence of the slaughter process on the stability should be determined. Thermophilic Campylobacter spp. from eight poultry flocks were isolated from cloacal swabs, carcasses and offal at different abattoir processing steps to determine their stability. DNA-fingerprinting was done using Pulsed-Field Gel Electrophoresis (PFGE) with two enzymes (SmaI and KpnI) and ribotyping. More than 150 Campylobacter strains were ribotyped and these data were combined with the results of PFGE. Molecular typing showed that strains found in cloacal swabs before processing could also be isolated from carcasses and offal at different processing steps representing predominating stable strains. Strains with varying molecular pattern could additionally be detected at different processing steps. Both genotyping methods identified in agreement flock-specific strains. These remained stable through the slaughter of poultry and were not altered through the slaughter process. Despite the known genetic variability of thermophilic Campylobacter, stable predominant strains could be identified in the poultry slaughter process and those strains can thus enter the food chain.

Potential competitive exclusion bacteria from poultry inhibitory to Campylobacter jejuni and Salmonella

The objective of this study was to isolate from chickens potential competitive exclusion bacteria (CE) that are inhibitory to Campylobacter jejuni or Salmonella, or to both, for subsequent development of a defined CE product for use in poultry. Adult chickens from family farms, commercial farms, and broiler chicken research centers were sampled to identify and select C. jejuni-free donor chickens. A challenge treatment, which included administering perorally 106 CFU C. jejuni per chicken and determining undetectable cecal shedding of campylobacters at 4 weeks, was important for identifying the best CE donor chickens. Screening of bacterial colonies obtained from nine donor chickens by using selective and nonselective media yielded 636 isolates inhibitory to six C. jejuni strains in vitro, with 194 isolates being strongly inhibitory. Of the 194 isolates, 145 were from ceca, and 117 were facultative anaerobic bacteria. One hundred forty-three isolates were inhibitory to six strains of Salmonella (including five different serotypes) in vitro. Of these, 41 were strongly inhibitory to all C. jejuni and Salmonella strains evaluated, and most were Lactobacillus salivarius. A direct overlay method, which involved directly applying soft agar on plates with discrete colonies from mucus scrapings of gastrointestinal tracts, was more effective in isolating CE than was the frequently practiced isolation method of picking and transferring discrete colonies and then overlaying them with soft agar. The best approach for obtaining bacteria highly inhibitory to Salmonella and C. jejuni from chickens was to isolate bacteria from ceca under anaerobic conditions. Free-range chickens from family farms were better donors of potential CE strongly inhibitory to both Salmonella and Campylobacter than were chickens from commercial farms and broiler chicken research centers.

Free-range layer chickens as a source of Campylobacter bacteriophage

Bacteriophage specific for Campylobacter were isolated from chicken excreta collected from established free-range layer breed stock. Bacteriophage were either propagated on a Campylobacter jejuni host with broad susceptibility to bacteriophage (NCTC 12662) or on Campylobacter isolates from the same samples. Campylobacters were confirmed as being C. jejuni and or C. coli, using a combination of standard biochemical tests and PCR analysis with genus and species specific primers. The bacteriophage displayed differential patterns of susceptibility against reference NCTC strains and contemporary C. jejuni /C. coli isolates from chicken excreta. Electron microscopy demonstrated that the phage possessed icosahedral heads and rigid contractile tails. Pulsed-field gel electrophoresis revealed the bacteriophage genomes to be double stranded DNA in the range of 140 kb in size and the restriction enzyme patterns of the DNAs indicate they are genetically related members of the Myoviridae family. This study showed that Campylobacter bacteriophage could easily be isolated from free-range chickens and form part of their normal microbiological biota of environmentally exposed birds.

Tracing flock-related Campylobacter clones from broiler farms through slaughter to retail products by pulsed-field gel electrophoresis

A total of 237 Campylobacter isolates from broiler flocks at farm (45 isolates) and slaughter (192 isolates) were typed by pulsed-field gel electrophoresis (PFGE) for epidemiological tracing studies. For PFGE, a modification of the Campynet method was used, which was standardized in a European Union project. The goal of the study was to trace flock-related Campylobacter clones through the whole production chain, from farm through slaughter to retail products, to investigate the introduction of thermophilic Campylobacter spp. on incoming contaminated carcasses during processing to the final products. The results of this study showed that identical clones of this pathogen, which had previously been found within the flocks during primary production, were also detected at individual stages of processing, including final products, which were packed and ready for sale. Most of the detected clones dominated during primary production and at slaughter. This study found PFGE to be suitable for examining epidemiological field data in the same region and time contexts. The discriminatory power of SmaI restriction enzyme digestion was sufficient. Relationships of the isolated Campylobacter strains could be confirmed by use of a second restriction enzyme, KpnI.

A longitudinal study of Salmonella and Campylobacter jejuni isolates from day of hatch through processing by automated ribotyping

Comparisons of bacterial populations over long periods of time allow researchers to identify clonal populations, perhaps those responsible for contamination of farms or humans. Salmonella and Campylobacter can cause human illness, and our objective was to use a library typing system to track strains that persist in the poultry house and through the processing plant. Two farms, over four consecutive flocks, were studied. Multiple samples were taken of the poultry house environment, feed mill, transport crates, and carcasses in the processing plant. Sample collection on the farm took place on chick placement day, midgrowout, and the day of harvest. This study found that 80.3% of isolates belonged to a single strain of Salmonella Kentucky that persisted in several environmental samples for all flocks at both farms, from chick placement day to the final product at the plant. Surgical shoe covers produced most isolates (n = 26), and processing day yielded the highest recovery (n = 68). Additional serotypes were recovered, but the Salmonella Kentucky-positive eggshells and chick mortality appeared to be the source of the organism for both farms. All Campylobacter isolates recovered were identified as C. jejuni. Most Campylobacter isolates (90.1%) belonged to one of three core strains. C. jejuni was not recovered on chick placement day. Cecal droppings yielded all nine strains. Most isolates (98.2%) were from one farm. Cluster analysis grouped C. jejuni and Salmonella isolates into four and six distinct clusters, respectively, on the basis of a similarity level of 80%.

Analysis of Campylobacter spp. contamination in broilers from the farm to the final meat cuts by using restriction fragment length polymorphism of the polymerase chain reaction products

We investigated the genotype diversity and dynamics of Campylobacter jejuni and Campylobacter coli in six commercial broiler farms during rearing and abattoir processing. In total, 223 C. jejuni and 36 C. coli strains isolated (on farm, transportation crates, carcasses after defeathering, and chicken wing meat at the end of the processing line) were subtyped by PCR-RFLP based on flagellin (fla typing) gene. Eleven (C. jejuni) and four (C. coli) different RFLP patterns were found. Multiple C. jejuni genotypes were identified in five out of six farms (except Farm 5). Furthermore, a clear tendency for dominance of particular genotypes was observed in almost all farms except Farm 3. Although diverse C. jejuni genotypes were isolated on the farms and transport crates, they were not detected in chicken wing cuts at the end of the processing line. We also observed varied distribution of types in different sampling stages both at the farm level and the processing environment. However, the interpretation of such fluctuations is precarious as new types occurred on some occasions, particularly during processing. Our results show that chicken wing meat contamination resulted mainly from farm strain carryover, and that the carcasses were probably contaminated during processing. In addition, the new strain types observed were isolated more frequently after defeathering as compared to other processing steps. Therefore, this stage, in addition to evisceration, is one of the critical control points in the processing line to prevent cross-contamination and for controlling the spread of campylobacters.

Prevalence and molecular profiles of Salmonella collected at a commercial turkey processing plant

In this study, whole carcasses were sampled at eight stages on a turkey-processing line and Salmonella prevalence was determined using enrichment techniques. Recovered Salmonella was further characterized using serotyping and the molecular profiles were determined using pulsed-field gel electrophoresis (PFGE). Prevalence data showed that contamination rates varied along the line and were greatest after defeathering and after chilling. Analysis of contamination in relation to serotypes and PFGE profiles found that on some visits the same serotype was present all along the processing line while on other days, additional serotypes were recovered that were not detected earlier on the line, suggesting that the birds harbored more than one serotype of Salmonella or there was cross-contamination occurring during processing. Overall, this study found fluctuations in Salmonella prevalence along a turkey-processing line. Following washing, Salmonella prevalence was significantly reduced, suggesting that washing is critical for Salmonella control in turkey processing and has significant application for controlling Salmonella at the postdefeathering and prechill stages where prevalence increased.

Transmission of Campylobacter spp. to chickens during transport to slaughter

AIMS

To determine the prevalence of Campylobacter-contaminated transport crates and to determine whether contaminated crates represent a risk for contamination of chickens during transport to slaughter.

METHODS AND RESULTS

Samples were collected from cleaned transport crates before they were dispatched to the farms. Chicken groups were sampled within 24 h before transport to slaughter and at the slaughterhouse. Campylobacter spp. were isolated from 69 of 122 (57%) sampled batches of transport crates. Twenty-six slaughter groups, negative at farm level, were transported in batches of crates from which Campylobacter spp. had been isolated. In 11 (42%) of these 26 slaughter groups, Campylobacter spp. were found in samples taken at slaughter. The corresponding figure for at-farm-negative slaughter groups transported in negative crates was four (15%) testing positive at slaughterhouse of 27 slaughter groups [relative risk (RR) = 2.9, 95% CI 1.1-7.3]. In four of 11 slaughter groups, genetic subtyping by pulsed-field gel electrophoresis was able to support the hypothesis of contamination from crates to chickens during transport to slaughter.

CONCLUSIONS

Despite washing and disinfection, crates were frequently contaminated with Campylobacter and it could have contaminated chickens during transport to slaughter.

SIGNIFICANCE AND IMPACT OF THE STUDY

Campylobacter-positive crates are a risk factor for chickens testing campylobacter-positive at slaughter.

Diversity of flaA genotypes among Campylobacter jejuni isolated from six niche-market poultry species at farm and processing

PCR-restriction fragment length polymorphism of the flagellin (flaA) gene in Campylobacter jejuni was used to determine the relationships of isolates collected at the farm and throughout processing for six niche-market poultry species. This study focused on two specialty chicken products, poussin and free range, and four other specialty products, squab, duck, guinea fowl, and quail. Cloacal and carcass samples were collected from three flocks from each of the six niche species. Three processing plants in California participated in a 2-year investigation. A total of 773 isolates from farm, posttransport, and the processing plants were genotyped, yielding a total of 72 distinct flaA profiles for the six commodities. Genetic diversity of C. jejuni at the farm was greatest for ducks with up to 12 distinct flaA types in two flocks and least for squab 1 flaA type between two farms. For two of the guinea fowl flocks, one free-range flock, two squab flocks, and all three poussin flocks, the flaA types recovered at the prepackage station matched those from the farm. Cross-contamination of poultry carcasses was supported by the observation of flaA types during processing that were not present at the farm level. New C. jejuni strains were detected after transport in ducks, guinea fowl, and free-range chickens. Postpicker, postevisceration, and prewash sampling points in the processing plant yield novel isolates. Duck and free-range chickens were the only species for which strains recovered within the processing plant were also found on the final product. Isolates recovered from squab had 56 to 93% similarity based on the flaA types defined by PCR-restriction fragment length polymorphism profiles. The 26 duck isolates had genetic similarities that ranged from 20 to 90%. Guinea fowl and free-range chickens each had 40 to 65% similarity between isolates. Poussin isolates were 33 to 55% similar to each other, and quail isolates were 46 to 100% similar. Our results continue to emphasize the need to clean processing equipment and posttransport crates in order to decrease cross contamination between flocks. This study also determined that several strains of C. jejuni had unique flaA types that could only be recovered in their host species.

Campylobacter contamination during poultry slaughter in Belgium

The relation between internal carriage and surface contamination with thermophilic Campylobacter species in broilers was examined by molecular typing methods. Samples from 39 flocks were collected in three Belgian poultry slaughterhouses. From each flock, crop swabs before slaughter and intestines and neck skins during slaughter were collected. A total of 309 isolates were identified at species level and further characterized by flagellin gene A PCR/restriction fragment length polymorphism and pulsed-field gel electrophoresis. Isolates were identified as Campylobacter jejuni (90%), Campylobacter coli (8.7%), and Campylobacter lari (2.2%), and 27 genotypes could be distinguished by combining the two molecular methods. Seventy-two percent of the flocks arriving at the abattoir were colonized with campylobacters. After slaughter, 79% of the flocks had contaminated neck skins. In six flocks, genotypes isolated from the neck skins were also found in the alimentary tract from previously slaughtered flocks. Four of these flocks were initially free of Campylobacter. These four flocks might have had no contaminated carcasses after logistic slaughtering.

Prevalence of Campylobacter and Salmonella Species on Farm, After Transport, and at Processing in Specialty Market Poultry

The prevalence of Campylobacter and Salmonella spp. was determined from live bird to prepackaged carcass for 3 flocks from each of 6 types of California niche-market poultry. Commodities sampled included squab, quail, guinea fowl, duck, poussin (young chicken), and free-range broiler chickens. Campylobacter on-farm prevalence was lowest for squab, followed by guinea fowl, duck, quail, and free-range chickens. Poussin had the highest prevalence of Campylobacter. No Salmonella was isolated from guinea fowl or quail flocks. A few positive samples were observed in duck and squab, predominately of S. Typhimurium. Free-range and poussin chickens had the highest prevalence of Salmonella. Post-transport prevalence was not significantly higher than on-farm, except in free-range flocks, where a higher prevalence of positive chickens was found after 6 to 8 h holding before processing. In most cases, the prevalence of Campylobacter- and Salmonella-positive birds was lower on the final product than on-farm or during processing. Odds ratio analysis indicated that the risk of a positive final product carcass was not increased by the prevalence of a positive sample at an upstream point in the processing line, or by on-farm prevalence (i.e., none of the common sampling stations among the 6 commodities could be acknowledged as critical control points). This suggests that hazard analysis critical control point plans for Campylobacter and Salmonella control in the niche-market poultry commodities will need to be specifically determined for each species and each processing facility.

Influence of inoculation levels and processing parameters on the survival of Campylobacter jejuni in German style fermented turkey sausages

This study investigated the influence of inoculum levels and manufacturing methods on the survival of Campylobacter (C.) jejuni in raw fermented turkey sausages. Sausages were prepared and inoculated with C. jejuni. After inoculation, these sausages were processed and ripened for 8 days. Samples were taken throughout the ripening process. The presence of C. jejuni was established bacteriologically. Additionally, lactic acid bacteria were enumerated, pH values and water activity were measured to verify the ripening process. To detect changes in genotype and verify the identity of the recovered clones, AFLP analysis was carried out on the re-isolated strains. Whereas no C. jejuni were detectable when inoculating the sausages with the lowest inoculum (0.08-0.44 log(10) cfu/g sausage emulsion), C. jejuni were detectable for 12-24h by enrichment when inoculated with approximately 2 log(10) cfu/g. After inoculation with 4 and 6 log(10) cfu/g respectively, C. jejuni were detectable without enrichment for 12-48 h and by enrichment for 144 h at the most. The greatest decrease of the C. jejuni population occurred during the first 4 h of ripening. Only a very high inoculum level allowed the survival of the organism during a fermentation process and during ripening to pose a potential risk for consumers. Lower initial Campylobacter inoculums will be eliminated during proper ripening of the sausages, if sufficient decrease in water activity and pH-value is ensured.

Phage therapy reduces Campylobacter jejuni colonization in broilers

The effect of phage therapy in the control of Campylobacter jejuni colonization in young broilers, either as a preventive or a therapeutic measure, was tested. A prevention group was infected with C. jejuni at day 4 of a 10-day phage treatment. A therapeutic group was phage treated for 6 days, starting 5 days after C. jejuni colonization of the broilers had been established. Treatment was monitored by enumerating Campylobacter colony forming units (CFU) and phage plaque forming units (PFU) from caecal content. Counts were compared with control birds not receiving phage therapy. A clear 3 log decline in C. jejuni counts was initially observed in the therapeutic group, however, after 5 days bacterial counts stabilized at a level 1 log lower than that of the control group. Colonization of C. jejuni in the prevention group was delayed by the treatment and after an initial 2 log reduction, colonization stabilized within a week at levels comparable to the therapeutic group. The CFU and PFU counts displayed opposing highs and lows over time, indicative of alternating shifts in amplification of bacteria and phages. There were no adverse health effects from the phage treatment. Two different phages were combined as therapeutic treatment of Campylobacter positive chickens challenged at the age approaching broiler harvest. This again resulted in a significant decrease in Campylobacter colonization. We conclude that phage treatment is a promising alternative for reducing C. jejuni colonization in broilers.

Genomic diversity of Campylobacter coli and Campylobacter jejuni isolates recovered from free-range broiler farms and comparison with isolates of various origins

In many industrialized countries, the incidence of campylobacteriosis exceeds that of salmonellosis. Campylobacter bacteria are transmitted to humans mainly in food, especially poultry meat products. Total prevention of Campylobacter colonization in broiler flocks is the best way to reduce (or eliminate) the contamination of poultry products. The aim of this study was to establish the sources and routes of contamination of broilers at the farm level. Molecular typing methods (DNA macrorestriction pulsed-field gel electrophoresis and analysis of gene polymorphism by PCR-restriction fragment length polymorphism) were used to characterize isolates collected from seven broiler farms. The relative genomic diversity of Campylobacter coli and Campylobacter jejuni was determined. Analysis of the similarity among 116 defined genotypes was used to determine clusters within the two species. Furthermore, evidence of recombination suggested that there were genomic rearrangements within the Campylobacter populations. Recovery of related clusters from different broiler farms showed that some Campylobacter strains might be specifically adapted to poultry. Analysis of the Campylobacter cluster distribution on three broiler farms showed that soil in the area around the poultry house was a potential source of Campylobacter contamination. The broilers were infected by Campylobacter spp. between days 15 and 36 during rearing, and the type of contamination changed during the rearing period. A study of the effect of sanitary barriers showed that the chickens stayed Campylobacter spp. free until they had access to the open area. They were then rapidly colonized by the Campylobacter strains isolated from the soil.

Reduction of Campylobacter spp. by commercial antimicrobials applied during the processing of broiler chickens: a review from the United States perspective

A reduction in Campylobacter spp. has been associated with use of commercial antimicrobial technologies during the processing of broiler chickens. This review is focused on commercial interventions that have received approval by both the U.S. Food and Drug Administration and the U.S. Department of Agriculture for use on raw poultry in the United States. Most of these interventions are currently applied prechill. The limited number of publications on the topic suggests that the application of antimicrobials in commercial settings results in Campylobacter reduction of 1 to 2 log CFU/ml of carcass rinse. However, postchill counts of 0.5 to 1 log CFU/ml of carcass rinse (approximately 4,000 CFU per carcass) are still common. Thus, antimicrobial interventions are not a complete solution for the control of Campylobacter on raw poultry. New postchill interventions are needed, as are (i) improvements in the methodology for detection and enumeration of Campylobacter, (ii) additional surveys on the contamination of processed poultry, and (iii) an understanding of possible resistance to antimicrobials by Campylobacter spp. Research addressing these topics will lead to better control of Campylobacter in commercial poultry carcasses.

Effect of preslaughter events on prevalence of Campylobacter jejuni and Campylobacter coli in market-weight turkeys

The effects of events which occur prior to slaughter, such as loading, transport, and holding at an abattoir, on the prevalence of Campylobacter species, including Campylobacter jejuni and Campylobacter coli, were examined. Cloacal swabs from market-weight turkeys in each of five flocks were obtained on a farm prior to loading (time 1; 120 swabs per flock) and after transport and holding at the abattoir (time 2; 120 swabs per flock). A statistically significant increase in the overall prevalence of Campylobacter spp. was observed for cloacal swabs obtained from farm 3 following transport (P < 0.01). At time 2, an increase in the prevalence of C. coli was also noted for cloacal swabs from farms 3, 4, and 5 (P < 0.01). Neither the minimum time off of feed nor the distance transported from the farm to the abattoir was correlated with the increase in C. coli prevalence. Similarly, responses to an on-farm management questionnaire failed to detect any factors contributing to the observed changes in Campylobacter sp. prevalence. A SmaI macrorestriction analysis of Campylobacter sp. isolates recovered from flock 5 indicated that C. coli was more diverse than C. jejuni at both time 1 and time 2 (P < 0.01), based on a comparison of the Shannon indices of diversity and evenness.

Genotype dynamics of Campylobacter jejuni in a broiler flock

We investigated the genotype diversity and dynamics of Campylobacter in a commercial broiler flock during rearing and slaughter. In total, 220 Campylobacter jejuni isolates collected on four sampling occasions during rearing and from routine sampling during slaughter were subtyped by SmaI macrorestriction and pulsed-field gel electrophoresis, PFGE. Eight different SmaI types were found. During rearing, a subsequent addition of genotypes occurred, with two SmaI types found at 2 weeks of age and six types on the day before slaughter. All types that were detected in more than one isolate were also found on all succeeding sampling occasions, including the slaughter sampling. Two new types were found in the slaughter samples. In two-thirds of the individual birds sampled the day before slaughter, more than one SmaI type were found, although there was a clear tendency for dominance of one type in individual birds. Our results show that multiple genotypes of C. jejuni may be present in a commercial broiler flock during rearing and even in gastrointestinal tracts of individual birds. Both recurring environmental exposure and genetic changes within the population may explain the genotype diversity. Although the distribution of genotypes varied between different sampling occasions, we found no indication that any subtype excluded another during the rearing of the broiler flock.

Predicted quantitative effect of logistic slaughter on microbial prevalence

Logistic slaughter is an intervention measure intended to reduce cross-contamination during slaughter by slaughtering contaminated units (=(groups of) animals) last. This paper describes a simple mathematical model which predicts the prevalences of contaminated units after logistic and random-order slaughter. The effect of logistic slaughter is the difference between these prevalences. The model assumes that uncontaminated units can become contaminated by contaminated units that were slaughtered before them; the contributions of contaminated units are independent. It also assumes that a slaughterhouse is uncontaminated at the start of the day and that a unit that is contaminated before slaughter also is contaminated after slaughter. The model was analysed using numerical simulations; for a selection of cases, analytical formulas can be derived and are presented. Contamination of broiler flocks with Salmonella was used as a case study. Even for this simple model, data availability is a problem leading to uncertain parameter estimates. An average cross-contamination scenario predicts that the beneficial effect of logistic slaughter is as low as 9.1%, which casts doubt on its usefulness as an intervention measure. The case study produced these general model results: the effect of logistic slaughter increases with the probability of cross-contamination between units; with the length of the slaughter queue; and with sensitivity (the probability of a positive test from a unit contaminated at the start of slaughter). However, the effect is small if the prevalence of contaminated units before slaughter is low or high.

Influence of bird strain on competitive exclusion of Campylobacter jejuni in young chicks

1. Newly hatched chicks of either layer or broiler strain were treated orally at regular intervals with either homologous or heterologous gut-flora preparations from young donor birds, in an attempt to prevent subsequent colonisation with Campylobacter jejuni by 'competitive exclusion' (CE). 2. Donors of 3 to 10 d of age were chosen to correspond with the period in which intensively reared poultry are least likely to become colonised with Campylobacter. 3. In two separate trials, material from donor layer hens (ISA Brown) protected male chicks of the same strain against a low (195 to 360 cfu/bird) Campylobacter challenge, but the same kind of material was ineffective when administered to chicks of a broiler strain (JA957). 4. Two further trials involved treatment preparations from young broilers, which failed to prevent Campylobacter colonisation of broiler chicks, even when colonisation occurred relatively slowly from a challenge of 90 to 94 cfu/bird. 5. It was concluded that any CE effect observed was strongly dependent on bird strain.

The incidence of Campylobacter spp. on processed turkey from processing plants in the midwestern United States

AIM

The primary aim of this study was to determine the incidence of Campylobacter spp. on turkey, presented for processing at participating production plants located in the midwest region of the United States.

METHODS AND RESULTS

The two participating plants were visited on a monthly basis for a period of 1 year. Sampling of carcasses was carried out using a surface swab technique. Swabs were obtained from carcasses at two points on the production line - prechill and postchill. In addition, samples of chill water were also obtained for examination. Isolation and detection of Campylobacter was carried out using enrichment in Preston broth with recovery of the organism on blood free Campylobacter selective agar (CCDA). Isolates recovered were screened and identified using the API Campy identification system. The study found that 34.9% of all samples tested were positive for Campylobacter spp. The overall, contamination rates observed for both plants were relatively similar (39.2% for plant A and 30.6% for plant B). Differences were observed in the incidence of Campylobacter spp. on prechill vs postchill carcasses (i.e. 40.8% prechill vs 37.6% postchill for plant A and 41.8% prechill vs 19.8% postchill for plant B). Campylobacter species most often isolated included Camp. jejuni and Camp. coli. Other species recovered were Camp. fetus fetus, Camp. upsaliensis and Camp. lari.

CONCLUSIONS

The incidence of Campylobacter spp. on processed poultry was relatively common. Factors such as the processing plant examined, season and the farms presenting birds for processing influenced the incidence of the pathogen.

SIGNIFICANCE AND IMPACT OF THE STUDY

Differences were observed in the prevalence of Campylobacter spp. isolated from the two plants examined. The study suggests a seasonal prevalence of Campylobacter in the cooler months with processing conditions also influencing the overall occurrence of the organism. The incidence, isolation and detection of Campylobacter spp. from processed poultry are discussed.

Effect of incubation temperature on isolation of Campylobacter jejuni genotypes from foodstuffs enriched in Preston broth

Preston broth and agar incubated at either 37 or 42 degrees C have been widely used to isolate campylobacters from foodstuffs. The consequences of using either incubation temperature were investigated. Retail packs of raw chicken (n = 24) and raw lamb liver (n = 30) were purchased. Samples were incubated in Preston broth at 37 and 42 degrees C and then streaked onto Preston agar and incubated as before. Two Campylobacter isolates per treatment were characterized. Poultry isolates were genotyped by random amplification of polymorphic DNA (RAPD), pulsed-field gel electrophoresis (PFGE), and flagellin PCR-restriction fragment length polymorphism, and lamb isolates were genotyped by RAPD only. In total, 96% of the poultry and 73% of the lamb samples yielded campylobacters. The lamb isolates were all Campylobacter jejuni, as were 96% of the poultry isolates, with the remainder being Campylobacter lari. The incubation temperature had no significant effect on the number of positive samples or on the species isolated. However, genotyping of the C. jejuni isolates revealed profound differences in the types obtained. Overall (from poultry and lamb), the use of a single incubation temperature, 37 degrees C, gave 56% of the total number of RAPD C. jejuni genotypes, and hence, 44% remained undetected. The effect was especially marked in the poultry samples, where incubation at 37 degrees C gave 47% of the PFGE genotypes but 53% were exclusively recovered after incubation at 42 degrees C. Thus, the incubation temperature of Preston media selects for certain genotypes of C. jejuni, and to detect the widest range, samples should be incubated at both 37 and 42 degrees C. Conversely, genotyping results arising from the use of a single incubation temperature should be interpreted with caution.