A Mathematical Modeling Approach to Uncover Factors Influencing the Spread of Campylobacter in a Flock of Broiler-Breeder Chickens

Despite continued efforts to improve biosecurity protocols, Campylobacter continues to be detected in the majority of commercial chicken flocks across Europe. Using an extensive data set of Campylobacter prevalence within a chicken breeder flock for over a year, multiple Bayesian models are presented to explore the dynamics of the spread of Campylobacter in response to seasonal variation, species-specificity, bird health, and total colonization prevalence. These models indicated that birds within the flock varied greatly in their response to bacterial challenge, and that this phenomenon had a large impact on the overall prevalence of different species of Campylobacter. Campylobacter jejuni appeared more frequently in the summer, while Campylobacter coli persisted for a longer duration, amplified by the most susceptible birds in the flock. Our study suggests that strains of Campylobacter that appear most frequently likely possess no demographic advantage, but are instead amplified due to the health of the birds that ingest it.

Impact of human Campylobacter infections in Southeast Asia: The contribution of the poultry sector

Campylobacter is globally recognized as a major cause of foodborne infection in humans, whilst the development of antimicrobial resistance and the possibility of repelling therapy increase the threat to public health. Poultry is the most frequent source of Campylobacter infection in humans, and southeast Asia is a global leader in poultry production, consumption, and exports. Though three of the world's top 20 most populated countries are located in southeast Asia, the true burden of Campylobacter infection in the region has not been fully elucidated. Based on published data, Campylobacter has been reported in humans, animals, and food commodities in the region. To our knowledge, this study is the first to review the status of human Campylobacter infection in southeast Asia and to discuss future perspectives. Gaining insight into the true burden of the infection and prevalence levels of Campylobacter spp. in the southeast Asian region is essential to ensuring global and regional food safety through facilitating improvements in surveillance systems, food safety regulations, and mitigation strategies.

Variation in Campylobacter Multilocus Sequence Typing Subtypes from Chickens as Detected on Three Plating Media

The objective of this study was to compare subtypes of Campylobacter jejuni and Campylobacter coli detected on three selective Campylobacter plating media to determine whether each medium selected for different subtypes. Fifty ceca and 50 carcasses (representing 50 flocks) were collected from the evisceration line in a commercial broiler processing plant. Campylobacter was cultured and isolated from cecal contents and carcass rinses on Campy-Cefex, Campy Line, and RF Campylobacter jejuni/coli agars. When a positive result was obtained with all three media, one colony of the most prevalent morphology on each medium was selected for further analysis by full genome sequencing and multilocus sequence typing. Sequence types were assigned according to PubMLST. A total of 49 samples were positive for Campylobacter on all three media. Forty samples contained only C. jejuni , three had only C. coli , and both species were detected in six samples. From 71% of samples, Campylobacter isolates of the same sequence type were recovered on all three media. From 81.6% of samples, isolates were all from the same clonal complex. From significantly fewer samples (26%, P < 0.01), one medium recovered an isolate with a sequence type different from the type recovered on the other two media. When multiple sequence types were detected, six times the medium with the odd sequence type was Campy-Cefex, four times it was Campy-Line, and six times it was RF Campylobacter jejuni/coli . From one sample, three sequence types were detected. In most cases, all three plating media allowed detection of the same type of Campylobacter from complex naturally contaminated chicken samples.

Influence of enrichment and isolation media on the detection of Campylobacter spp. in naturally contaminated chicken samples

Investigating Campylobacter epidemiology requires adequate technique and media to ensure optimal culturing and accurate detection and isolation of Campylobacter strains. In the present study, we investigated the performances of three enrichment durations in Bolton broth (0, 24 and 48h) and compared four isolation media (mCCDA, Karmali, Butzler no. 2 and CampyFood agar (CFA)) for the detection of Campylobacter positive samples and the identification of Campylobacter species, from naturally contaminated broiler chicken samples (caeca, neck skin from carcasses, and skin from thighs). We compared our local results to those we obtained with samples from a European survey (caeca and neck skin) and a national survey (neck skin, thigh skin, and breast). Direct plating favored the detection of positive samples highly contaminated by Campylobacter (caeca and neck skin from carcasses) whatever the media. A longer enrichment reduced the rates of Campylobacter recovery except when using Butzler no. 2, more particularly for neck skin which background microflora was less important than in caeca. As a matter of fact, enrichment allowed a higher detection rate of positive samples with low Campylobacter contamination levels (breast, thigh skin), this detection being enhanced when using Butzler no. 2. When comparing the 3 other selective media, CFA was the 2nd most efficient media prior to mCCDA and Karmali. Interestingly, enrichment promoted the growth of Campylobacter coli but this promotion was least with Butzler no. 2 agar. Our study has confirmed the need to adapt the method to the types of samples for improving the detection of Campylobacter and that the method may affect the prevalence of the species.

The long-term dynamics of Campylobacter colonizing a free-range broiler breeder flock: an observational study

A free-range broiler breeder flock was studied in order to determine the natural patterns of Campylobacter colonization over a period of 63 weeks. Campylobacter sequence types (STs) were not mutually exclusive and on average colonized only 17.7% of the birds tested at any time. Campylobacter STs typically reached a peak in prevalence upon initial detection in the flock before tailing off, although the ST and antigenic flaA short variable region in combination were stable over a number of months. There was evidence that, with a couple of exceptions, the ecology of C. jejuni and C. coli differed, with the latter forming a more stable population. Despite being free range, no newly colonizing STs were detected over a 6-week period in autumn and a 10-week period in winter, towards the end of the study. There was limited evidence that those STs identified among broiler chicken flocks on the same farm site were likely to colonize the breeder flock earlier (R(2) 0.16, P 0.01). These results suggest that there is natural control of Campylobacter dynamics within a flock which could potentially be exploited in designing new intervention strategies, and that the two different species should perhaps be considered separately.

Antimicrobial resistance of Campylobacter jejuni and Campylobacter coli from poultry in Italy

This study was aimed at assessing the antimicrobial resistance (AMR) of Campylobacter isolates from broilers and turkeys reared in industrial farms in Northern Italy, given the public health concern represented by resistant campylobacters in food-producing animals and the paucity of data about this topic in our country. Thirty-six Campylobacter jejuni and 24 Campylobacter coli isolated from broilers and 68 C. jejuni and 32 C. coli from turkeys were tested by disk diffusion for their susceptibility to apramycin, gentamicin, streptomycin, cephalothin, cefotaxime, ceftiofur, cefuroxime, ampicillin, amoxicillin+clavulanic acid, nalidixic acid, flumequine, enrofloxacin, ciprofloxacin, erythromycin, tilmicosin, tylosin, tiamulin, clindamycin, tetracycline, sulfamethoxazole+trimethoprim, chloramphenicol. Depending on the drug, breakpoints provided by Comité de l'antibiogramme de la Société Française de Microbiologie, Clinical and Laboratory Standards Institute, and the manufacturer were followed. All broiler strains and 92% turkey strains were multidrug resistant. Very high resistance rates were detected for quinolones, tetracycline, and sulfamethoxazole+trimethoprim, ranging from 65% to 100% in broilers and from 74% to 96% in turkeys. Prevalence of resistance was observed also against ampicillin (97% in broilers, 88% in turkeys) and at least three cephalosporins (93-100% in broilers, 100% in turkeys). Conversely, no isolates showed resistance to chloramphenicol and tiamulin. Susceptibility prevailed for amoxicillin+clavulanic acid and aminoglycosides in both poultry species, and for macrolides and clindamycin among turkey strains and among C. jejuni from broilers, whereas most C. coli strains from broilers (87.5%) were resistant. Other differences between C. jejuni and C. coli were observed markedly in broiler isolates, with the overall predominance of resistance in C. coli compared to C. jejuni. This study provides updates and novel data on the AMR of broiler and turkey campylobacters in Italy, revealing the occurrence of high resistance to several antimicrobials, especially key drugs for the treatment of human campylobacteriosis, representing a potential risk for public health.

Comparative analysis of Campylobacter populations within individual market-age broilers using Fla gene typing method

Campylobacter species is the most common human pathogen causing gastrointestinal infections in humans, and poultry is considered a major source of this pathogen. In this project, we aim to study the genetic diversity of Campylobacter populations within individual chickens using cecal samples to understand the nature of intestinal colonization in chickens by Campylobacter species. Genotyping was conducted based on the DNA sequence of short variable regions (SVR) in the flaA gene. Cecal samples were collected from 9 market-age broiler chickens and used for isolation of Campylobacter genomic DNA. The SVR fragments of 400 bp were amplified using SVR-specific primers, cloned, and sequenced. Sequencing results obtained from 86 clones (~10 clones/bird) showed that on an average 23.25% of clones had mutations within individuals. The mutations did not show any consistent pattern, suggesting a random nature of the mutations. When translated SVR sequences were analyzed, on average 20.57% of strains carried altered amino acid sequences in SVR within individuals. Four translated sequences had nonsense mutations to produce truncated proteins. These results suggest that there are multiple genotypes colonizing in a cecum and the occurrence of truncated FlaA protein may represent a novel mechanism for evasion of adaptive immune responses.

Comparative genotypic and antimicrobial susceptibility analysis of zoonotic Campylobacter species isolated from broilers in a nationwide survey, Portugal

Campylobacter is a major cause of human foodborne disease worldwide and has been associated with the consumption of contaminated poultry. The prevalence of Campylobacter species in broiler flocks from more than 200 producers widespread in mainland Portugal was assessed in 2008 in response to Commission Decision 2007/516/EC. Campylobacter isolates were obtained from 83.3% of 424 pooled cecal samples, with a higher prevalence of Campylobacter coli (61.2%) than Campylobacter jejuni (38.8%). Restriction fragment length polymorphism analysis of the flaA gene (flaA-RFLP) of 112 C. coli isolates and 67 C. jejuni isolates yielded 11 flaA-RFLP patterns with HinfI (Hunter Gaston diversity index [HGDI] = 0.62) and 48 flaA-RFLP patterns with DdeI (HGDI = 0.89), indicating a high level of genetic diversity. A wide geographic distribution of the most frequent restriction pattern was observed. MICs of five antimicrobials (ciprofloxacin, gentamicin, streptomycin, erythromycin, and tetracycline) were determined for 215 C. coli isolates and 136 C. jejuni isolates. The occurrence of non-wild-type isolates, exhibiting an acquired resistance phenotype, was higher for C. coli than C. jejuni for all antimicrobials tested. Sixty-three percent of C. jejuni and C. coli isolates were considered non-wild type based on their response to both ciprofloxacin and erythromycin, which are frequently used in the treatment of human infections. The high prevalence of antimicrobial-resistant Campylobacter strains detected supports the need for increased epidemiological surveillance and prevention in a country where large amounts of poultry meat are consumed.

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.

Typing of Campylobacter jejuni isolates from dogs by use of multilocus sequence typing and pulsed-field gel electrophoresis

Campylobacter is a major cause of human gastroenteritis worldwide. Risk of Campylobacter infection in humans has been associated with many sources, including dogs. This study aimed to investigate whether C. jejuni carried by dogs could potentially be a zoonotic risk for humans and if there were common sources of C. jejuni infection for both humans and dogs. Multilocus sequence typing (MLST) together with macrorestriction analysis of genomic DNA using SmaI and pulsed-field gel electrophoresis (PFGE) were both used to analyze 33 C. jejuni isolates obtained from various dog populations, including those visiting veterinary practices and from different types of kennels. MLST data suggested that there was a large amount of genetic diversity between dog isolates and that the majority of sequence types found in isolates from these dogs were the same as those found in isolates from humans. The main exception was ST-2772, which was isolated from four samples and could not be assigned to a clonal complex. The most commonly identified clonal complex was ST-45 (11 isolates), followed by ST-21 (4 isolates), ST-508 (4 isolates), and ST-403 (3 isolates). The profiles obtained by macrorestriction PFGE were largely in concordance with the MLST results, with a similar amount of genetic diversity found. The diversity of sequence types found within dogs suggests they are exposed to various sources of C. jejuni infection. The similarity of these sequence types to C. jejuni isolates from humans suggests there may be common sources of infection for both dogs and humans. Although only a small number of household dogs may carry C. jejuni, infected dogs should still be considered a potential zoonotic risk to humans, particularly if the dogs originate from kennelled or hunt kennel dog populations, where the prevalence may be higher.