Prevalence of and risk factors for Campylobacter spp. contamination of broiler chicken carcasses at the slaughterhouse

A study was conducted in 2008 to estimate the prevalence and identify the risk factors for Campylobacter spp. contamination of broiler carcasses during the slaughtering process. A pool of 10 caeca and one carcass were collected from 425 batches of broiler chickens slaughtered in 58 French slaughterhouses over a 12-month period. Potential risk factors were identified according to the Campylobacter contamination status of carcasses and processing variables identified from questionnaires. The statistical analysis took into account confounding factors that have already been associated with the presence of Campylobacter on carcasses such as the slaughter age of the chicken or seasonal variations. Campylobacter spp. were isolated from 77.2% of caeca (95% CI 73.2 to 81.2) and from 87.5% of carcasses (95% CI 84.4 to 90.7). A multiple logistic regression showed 4 parameters as significant risk factors (p < 0.05) for contamination: (I) batches were not the first to be slaughtered in the logistic schedule (OR = 3.5), (II) temperature in the evisceration room was higher than 15 °C (OR = 3.1), (III) dirty marks on carcasses after evisceration were visible (OR = 2.6) and (IV) previous thinning of the flocks, from which slaughtered batches came, had occurred at the farm (OR = 3.3). This last result highlighted the need for sanitary precautions to be taken when catching birds for transport. At the slaughterhouse, evisceration seemed to be the operation contributing most to the spread of contamination. Effective risk management solutions could include the systematic external rinsing of carcasses after evisceration and the implementation of slaughtering schedules according to the Campylobacter contamination status of flocks.     

Campylobacter contamination in broiler carcasses and correlation with slaughterhouses operational hygiene inspection

This study investigates factors associated with Campylobacter contamination of broiler carcasses, using survey data collected from nine Belgian slaughterhouses in 2008 in accordance with a European Union baseline study. Campylobacter were detected in 51.9% (202/389) (95% confidence interval, 46.8%-56.9%) of broiler carcasses. Campylobacter concentration was <10 CFU/g in 49.6% of carcasses, while 20.6% were contaminated with ≥1000 CFU/g. The mean Campylobacter concentration, as calculated by maximum likelihood estimation for left-censored data, was 1.8 log₁₀ CFU/g, with a standard deviation of 1.9 log₁₀ CFU/g. There was statistically significant variation among slaughterhouses in prevalence and concentrations of Campylobacter in their sampled carcasses. Campylobacter prevalence (but not concentrations) was positively associated with increase in broilers age. Both Campylobacter prevalence and concentration were significantly higher in carcasses sampled during June and September (but not in July and August) than carcasses sampled in January. We also investigated the correlation (Spearman’s rank correlation test) between the scores of official control inspections and Campylobacter prevalence for eight out of the nine slaughterhouses. The control inspections were routinely performed by the Belgian Federal Agency for the Safety of the Food Chain, and the concluded inspection scores were used as a general numerical indicator for the status of operational hygiene and quality of management in the slaughterhouses. Ranking of slaughterhouses based on their inspection scores was statistically correlated (Spearman’s correlation coefficient = 0.857) with their ranking based on prevalence of Campylobacter. In the present study we demonstrate how the outcomes from a routine baseline survey could be coupled with other readily available data from national control authorities in order to enable a better insight over Campylobacter contamination status in broiler slaughterhouses. Findings from this work call for subsequent in-depth investigations on technical and hygiene management factors that could impact Campylobacter contamination across broiler slaughterhouses.     

Factors associated with carcass contamination by Campylobacter at slaughterhouse in cecal-carrier broilers

A study was conducted in 2009 to identify risk factors of Campylobacter spp. transmission from the digestive tract to the carcasses of standard broilers (slaughter age: 37 day, carcass weight: 1.3 kg on average). Counts of Campylobacter were performed on pools of 10 ceca and 10 neck-skins from 108 Campylobacter ceca-positive batches in three slaughterhouses. Technical and health data also was collected on the broilers: age, size, carcass weight (mean and standard deviation), condemnation rate, mortality rate and nature of treatment during the rearing period.Cecal counts varied from 4.8 to 10.2 log₁₀ cfu/g. In seventeen batches (15.7%), the skin count was below the detection limit. In the 91 batches with positive neck-skin test results, the counts varied from 2.0 to 5.2 log₁₀ cfu/g. Standard deviation of carcass weight, condemnation rate, slaughter rate and cecal count were significantly lower and growth rate higher in the 17 batches where neck-skin results were not detected positive. Multivariate analysis showed that batches with higher standard deviation of carcass weight were 5 to 9 fold more at risk of having detectable carcass contamination. Among the 91 positive neck-skin batches, only slaughter rate and cecal counts were found to have a significant but limited effect on the level of neck-skin contamination. As far as body weight homogeneity may be affected by disease, better health control can contribute to a reduction of the contamination of the broiler carcasses in Campylobacter carrier batches.     

Molecular characterization and antibiotic resistance profiling of Campylobacter isolated from cattle in Polish slaughterhouses

A total of 812 samples from bovine hides and the corresponding carcasses collected at the slaughterhouse level in the eastern part of Poland were examined for the presence of Campylobacter jejuni and Campylobacter coli. Recovered isolates were confirmed using species-specific PCR, characterized by the presence of 11 putative virulence genes and antimicrobial susceptibility was determined using a microbroth dilution method. Furthermore, the genotypic relatedness of the isolates was determined by PFGE profiling and virulence pattern cluster analysis. The prevalence of Campylobacter was 25.6% and 2.7% in bovine hide and carcass samples, respectively. The presence of virulence markers varied between C. jejuni and C. coli species however, the majority of strains possessed the cadF, flhA, flaA genes, irrespective of the bacterial species and origin. The lower number of the strains was positive for the invasive associated markers – virB11 and wlaN. Antibiotic profiling showed that campylobacters were most frequently resistant to quinolones and fluoroquinolones (nalidixic acid and ciprofloxacin, 38.3% of each, respectively) followed by streptomycin (24.3%) and tetracycline (20.9%). Resistance to erythromycin and gentamicin was demonstrated in 4.3% and 2.6% of strains, respectively. Comparisons of the PFGE and virulence marker profiles of the isolates reflected the high genetic diversity of Campylobacter tested. Moreover, a poor correlation between the PFGE type, pathogenic gene marker and antimicrobial resistance patterns was observed.     

PorA specific primers for the identification of Campylobacter species in food and clinical samples

Campylobacteriosis is a public health problem with considerable socio-economic impact. As the European Food Safety Authority has emphasized the importance of a surveillance programme for campylobacteriosis, the aim of the present study was the optimization of a specific and sensitive PCR protocol able to detect Campylobacter species responsible for gastrointestinal infections. Raw poultry meat samples were analysed for the presence of Campylobacter sp., by plating onto mCCD (Modified Charcoal-Cefoperazone-Deoxycholate) Agar and Campylobacter Selective Preston Agar and using four sets of species-specific primers for Campylobacter jejuni, Campylobacter coli, Campylobacter upsaliensis and Campylobacter lari designed to bridge the porA gene. The resulting primers demonstrated a sensitivity of 0.01 ng/μl for the C. coli-specific, C. lari-specific, and C. upsaliensis-specific primer sets and 0.5 ng/μl for the C. jejuni-specific primer sets using DNA from pure cultures. Non-specific amplification of non-target DNA was not observed indicating excellent specificity. The primers were useful for the analyses of poultry meat samples both for direct plating onto mCCDA, and for DNA extracted directly from the cells grown for 48 h in Preston enrichment broth. The sets of primers were also useful when used for species identification of human isolates.     

The biofilm forming potential of bacterial species in the genus Campylobacter

The biofilm forming abilities of 16 strains representative of 14 of the 16 species comprising the genus Campylobacter were determined on glass, stainless steel, and polystyrene plastic. The formation of biofilms has been suggested as a means by which Campylobacter is able to persist within an inhospitable environment. Of the eight microaerophilic Campylobacter species, including two strains each of Campylobacter jejuni and Campylobacter fetus, only C. jejuni strain 81–176 reliably produced a visible biofilm on multiple surfaces. Alternately, all six strains of the anaerobic Campylobacter species reliably produced visible biofilms on multiple surfaces. Electron micrographs of the individual biofilms showed relatively homogeneous biofilms produced by the anaerobic strains, while the microaerophilic C. jejuni strain 81–176 produced a biofilm containing similar quantities of both the spiral and coccoid forms. This survey suggests a difference in the biofilm forming potentials and the morphologies of the bacteria comprising the biofilms between anaerobic and microaerophilic species of Campylobacter. Additionally, differences observed in the biofilm forming ability of two strains of C. jejuni suggest the need for a further investigation of the biofilm forming potential of this species using a larger number of strains.     

The temporal,PFGE and resistance pattern associations suggest that poultry products are only a minor source of human infections in Western Finland

In order to compare human and retail poultry meat thermophilic Campylobacter isolates originating in a regional area in Western Finland, minimum inhibitory concentration (MICs) for six antimicrobials (96 isolates) and pulsed-field gel electrophoresis (PFGE) (102 isolates) were analysed. Campylobacter spp. were detected in 10.5% out of 305 fresh poultry products studied; 29 (90.5%) isolates were identified as Campylobacter jejuni. Among the 70 human isolates, 66 (94.3%) isolates were identified as C. jejuni. Only one C. jejuni domestic poultry isolate showed resistance (ampicillin), whereas domestic human C. jejuni isolates were more commonly resistant to ciprofloxacin, nalidixic acid, ampicillin and tetracycline. The resistance in foreign human isolates was significantly more common than among domestic isolates. PFGE analysis with KpnI restriction enzyme resulted in 59 different PFGE types among the poultry and human isolates. Three types were detected first in poultry meat and thereafter during the following month in domestic human samples, whereas the other conjoint types were detected only after many months. This study suggests that poultry products play only a minor role in human campylobacteriosis in the study area and that the resistance found in domestic human isolates is not likely related to retail poultry meat products.     

Salmonella, Escherichia coli O157:H7 and E. coli biotype 1 in a pilot survey of imported and New Zealand pig meats

A pilot survey for the pathogens Salmonella and Escherichia coli O157:H7, and E. coli biotype 1 was conducted on 100 New Zealand-produced (domestic) pig carcasses and 110 imported pig meat samples over an 8-month period to assess the likelihood of introduction of novel pathogen strains into New Zealand (NZ), and as a guide for development of a domestic pork National Microbiological Database programme. Salmonella was not isolated from domestic pig carcasses or from pig meat imported from Canada and the USA. The prevalence of Salmonella in imported pig meat was 3.6% (95% CI 1.0–9.0) with positive samples detected from Australian pig meat. The prevalence of E. coli O157:H7 on domestic pig carcasses was 1% (95% CI 0.03–5.4) while the overall prevalence of E. coli O157:H7 in imported pig meat was 1.8% (95% CI 0.2–6.4), detected mainly from Australian but not from Canadian or US pork. All except three samples have an E. coli biotype 1 count of <100 CFU cm⁻² or g⁻¹, indicating good hygiene quality of domestic and imported pig meat. The results demonstrated that importation of uncooked pig meat is a potential route for the introduction of new clones of Salmonella and E. coli O157:H7 into New Zealand.     

Model of inactivation of Campylobacter jejuni in poultry scalding

The purpose of this study was to develop a model of inactivation of Campylobacter jejuni in industrial scalding of chickens. Models can be used as a guide for broiler slaughterhouse operations for reducing levels of C. jejuni contamination on broiler carcasses. Mean concentrations of C. jejuni in terms of colony forming units (CFU) in scald tank water and in carcass rinse solution after scalding were 2.90 ± 0.07 and 3.86 ± 0.11 LogCFU/mL, respectively. Scald tank water temperature, flow rate, pH, and total solids in scalding process water were 54.15 ± 0.2 °C, 172.0 ± 8.4 L/min, 8.0 ± 0.01, and 2565 ± 114.3 mg/L, respectively. Inactivation models were developed by using mass balances and literature data for inactivation kinetics, of Campylobacter and the Arrhenius equation. Results of the inactivation models of scalding process indicate that high temperature and short time (less than 2 min) of scalding process were effective in reducing the number of viable cells. For this experimental data more than 50% of the Campylobacter are inactivated on surfaces of the chickens. The model fits the experimental data well and the values of the estimated parameters provide insight for this process. The model can be used for process design and potential process modifications.     

Quantitative analysis of viable,stressed and dead cells of Campylobacter jejuni strain 81-176

Campylobacter jejuni is an important foodborne gastrointestinal pathogen and highly sensitive to environmental stresses. Research has shown that changes in culturability, cell morphology, and viability occur when C. jejuni cells are subjected to stresses. In this study, real-time PCR, ethidium monoazide (EMA) in combination with real-time PCR (EMA-PCR), BacLight bacterial viability staining, and agar plate counting methods were used to quantitatively analyze viable, stressed, and dead C. jejuni strain 81-176. The real-time PCR assay provides highly sensitive and specific quantification of total genome copies of C. jejuni culture in different growth phases. Our results also reveal that real-time PCR can be used for direct quantification of Campylobacter genome release into Phosphate Buffered Saline (PBS) as an indicator of cell lysis. Using EMA-PCR, we obtained a dynamic range of greater than 3 logs for differentiating viable vs. dead cells. The viability and morphological characteristics of the stressed cells after one-week incubation at 25 °C, in air, and under nutrient-poor conditions were investigated. Our results indicated that, over 99% of the stressed cells were converted from the spiral to the coccoid form and became non-culturable. However, more than 96% of the coccoid cells retained their membrane integrity as suggested by both the BacLight staining and EMA-PCR analyses. Thus, to detect C. jejuni under stress conditions, conventional culturing method in conjunction with EMA-PCR or BacLight staining might be a more appropriate approach.     

Survey of Salmonella contamination of edible nut kernels on retail sale in the UK

Consumption of nut kernels has shown an upward trend due to people's increasing tendency to eat healthy snacks. The purpose of this survey was to establish the microbiological safety of retail edible nut kernel samples of different varieties. Overall Salmonella spp. and Escherichia coli were detected from 0.1% and 0.8% of 2886 edible nut kernels, respectively. S. Senftenberg and S. Tennessee were detected from two pre-packed samples of Brazil nuts (0.4%) and S. Anatum from a pre-packed mixed nuts sample (0.9%; mix: almonds, Brazils, cashews, peanuts, walnuts) indicating a risk to health. The levels of Salmonella ranged from <0.01 to 0.23/g. E. coli at unsatisfactory levels (150/g) was present in another pre-packed Brazils nuts sample (0.2%). E. coli was additionally found at lower levels (range: 3.6–43/g) in Brazils (1.9%), macadamia (1.5%), pistachios (1.1%), walnuts (0.7%), peanuts (0.7%), hazels (0.5%), cashews (0.4%), and almonds (0.3%). Levels of E. coli did not correlate with the presence of Salmonella. The batches contaminated with Salmonella were recalled and Food Standards Agency food alerts were issued to advise against the consumption of the affected products. The presence of Salmonella is unacceptable in ready-to-eat foods and follows that the need for applying good agricultural and hygiene practices and effective decontamination procedures during the production of edible kernels cannot be overemphasized.     

Development and evaluation of aptamer magnetic capture assay in conjunction with real-time PCR for detection of Campylobacter jejuni

A prototype method for the concentration and detection of Campylobacter jejuni was developed using a previously reported biotinylated DNA aptamer in conjunction with qPCR. The so-called aptamer-based magnetic capture-qPCR (AMC-qPCR) assay was compared to a similar immunomagnetic separation (IMS)-qPCR assay. In small volume experiments (300 μl) applied to serially diluted C. jejuni suspended in buffer containing a mixed culture of other common food borne pathogens, the lower detection limit of the AMC-qPCR method was 1.1 log₁₀/300 μl C. jejuni cells, one log₁₀ better (lower) than that of IMS-qPCR (2.1 log₁₀ CFU/300 μl). AMC-qPCR capture efficiency was 10–13% at assay detection limit. In 10 ml scale-up experiments, the lower detection limit of AMC-qPCR was 2.0 log₁₀ CFU/10 ml with corresponding capture efficiency of 4–7%. Nucleic acid aptamers are promising alternatives to antibodies for magnetic bead-based capture followed by qPCR detection.     

Pulsed field gel electrophoresis typing of human and retail foodstuff Campylobacters: an Irish perspective

Campylobacter enteritis is a zoonosis, an infectious disease transmissible under normal conditions from vertebrate animals to man, presenting a major global public health burden. In this study, Pulsed Field Gel Electrophoresis (PFGE) was employed to identify common genotypes in a collection of 600 Campylobacter isolates in order to investigate if profiles obtained from retail samples of foodstuffs matched genotypes causing illness in the community in Ireland. The Campylobacters were isolated from retail foodstuffs, and cases of gastroenteritis, over the same 20-month period in three population centres in Ireland. The major observation made was of a high level of PFGE-genotype heterogeneity; 236 SmaI discrete genotypes were found in 507 strains successfully analysed. Analysis of the PFGE profiles revealed 22 common profiles amongst food isolates and those causing enteritis in humans. These cojoint PFGE genotypes indicate that 56 (38%) of the human clinical isolates are genetically related to 129 (36%) of the food isolates. The identification of these recurrent PFGE types, in the sampled Campylobacter coli and Campylobacter jejuni populations, indicates that a high proportion of Campylobacter isolates found in foods of animal origin also occur in patients with symptoms of enteritis. This data adds weight to the epidemiological hypothesis that a high proportion of human Campylobacter cases are contracted via the handling and consumption of contaminated foodstuffs, in particular poultry.     

In vitro antimicrobial activity of essential oil from endemic Origanum minutiflorum on ciprofloxacin-resistant Campylobacter spp.

This study evaluated the antimicrobial activities of an essential oil of Origanum minutiflorum (O. Schwarz and P.H. Davis) against ciprofloxacin-resistant Campylobacter spp., by broth microdilution and agar well-diffusion methods. Moreover, O. minutiflorum oil was analyzed by gas chromatography/mass spectrometry (GC/MS). Twenty-nine components were identified, representing 98.7 of the oil. The oil yield from the plants was 4.0–4.4% v/w. The major components of O. minutiflorum oil were carvacrol (73.9%) and p-cymene (7.20%). The oil has lower contents of carvacrol methyl ether (0.05%), heptadecanol (0.06%) and carvacryl acetate (0.06%). Twenty-one Campylobacter spp. (12 C. jejuni, 5 C. lari and 4 C. coli) strains using in this study were selected among 300 isolates according to their resistance to ciprofloxacin. The minimum inhibitory concentration (MIC) values for bacterial strains, which were sensitive to the essential oil of O. minutiflorum, were in the range of 7.8–800 μg/ml. The essential oil obtained showed strong antimicrobial activity against all of the tested ciprofloxacin-resistance Campylobacter spp. These results suggest that the essential of O. minutiflorum may be used as a natural preservative in food against food-born disease, such as Campylobacteriosis.     

Salmonella on feces,hides and carcasses in beef slaughter facilities in Venezuela

This study determined Salmonella prevalence at different stages during the slaughtering in three beef slaughter plants (A, B and C) located in the western region of Venezuela (Zulia and Lara states). Each facility was visited three times at monthly intervals, from the months October through December of 2006. Samples were collected from hides (n = 80), fecal grabs (n = 80) and carcasses (n = 80) at the phases of pre-evisceration, after-evisceration and pre-cooler at three sampling sites on the animals (rump, flank and brisket). Salmonella prevalence was higher on hides (36.3%) than on feces (13.8%) (P < 0.05). Differences among slaughter plants for overall Salmonella prevalence were observed (P = 0.001; A: 3.5%, B: 11.1%, C: 4.4%). From the isolated strains, Salmonella enterica subspecies enterica ser. Saintpaul, Salmonella ser. Javiana and Salmonella ser. Weltevreden were identified. Cattle feces and hides might be considered as important sources of Salmonella for carcass contamination at different slaughter stages. The presence of potentially pathogenic Salmonella serotypes at the slaughtering stages is an evidence of the circulation of this pathogen in the food environment; its presence could increase consumers' risks of infection if proper food handling and preparation techniques are not followed. These data should serve as a baseline for future comparisons in Salmonella prevalence on beef carcasses to be used by the government and industry in order to establish preventive measures and to better address the risks of Salmonella contamination.     

Microbiological quality of fresh lettuce from organic and conventional production

Previously there was no available information on the levels of indicator bacteria and the prevalence of pathogens in fresh lettuce grown in organic and conventional farms in Spain. A total of 72 lettuce samples (18 farms for 4 repetitions each) for each type of the agriculture were examined in order to assess the bacteriological quality of the lettuces, in particular the prevalence of selected pathogens. The lettuce samples were analyzed for the presence of aerobic mesophilic, psychrotrophic microorganisms, yeasts and moulds, Enterobacteriaceae, mesophilic lactic acid bacteria, Pseudomonas spp. and presumptive Escherichia coli, Salmonella spp. and Listeria monocytogenes. The mean aerobic mesophilic counts (AM) were 6.35 ± 0.69 log₁₀ cfu g⁻¹ and 5.67 ± 0.80 log₁₀ cfu g⁻¹ from organic and conventional lettuce, respectively. The mean counts of psychrotrophic microorganisms were 5.82 ± 1.01 log₁₀ cfu g⁻¹ and 5.41 ± 0.92 log₁₀ cfu g⁻¹ from organic and conventional lettuce, respectively. Yeasts and moulds (YM) mean counts were 4.74 ± 0.83 log₁₀ cfu g⁻¹ and 4.21 ± 0.96 log₁₀ cfu g⁻¹ from organic and conventional lettuce, respectively. Lactic acid bacteria (LAB) were present in low numbers and the mean counts were 2.41 ± 1.10 log₁₀ cfu g⁻¹ and 1.99 ± 0.91 log₁₀ cfu g⁻¹ from organic and conventional lettuce, respectively. Pseudomonas spp. mean counts were 5.49 ± 1.37 log₁₀ cfu g⁻¹ and 4.98 ± 1.26 log₁₀ cfu g⁻¹ in organic and conventional lettuce, respectively. The mean counts for Enterobacteriaceae were 5.16 ± 1.01 log₁₀ cfu g⁻¹ and 3.80 ± 1.53 log₁₀ cfu g⁻¹ in organic and conventional lettuce, respectively. E. coli was detected in 22.2% (16 samples) of organic lettuce and in 12.5% (9 samples) of conventional lettuce. None of the lettuce samples was positive for E. coli O157:H7, L. monocytogenes and Salmonella spp. From the samples analyzed by principal component analysis (PCA) a pattern with two different groups (conventional and organic) can be observed, being the highest difference between both kinds of samples the Enterobacteriaceae count.     

Investigation of Salmonella enterica in Sardinian slaughter pigs: prevalence, serotype and genotype characterization

In order to improve the knowledge about the presence of Salmonella in pork meat in Sardinia (Italy), the prevalence and the sources of Salmonella at 5 pig slaughterhouses (slaughtered pigs and environment) were investigated and the isolates were characterised. A total of 462 samples were collected, 425 from pigs at slaughter and 41 from the slaughterhouse environment. Salmonella was isolated from 26/85 (30.5%) mesenteric lymph nodes, 14/85 (16.4%) colon contents, and from 12/85 (14.1%) carcasses and livers. Salmonella prevalence was 38% (8/21) in samples from surfaces not in contact with meat, and 35% (7/20) in those from surfaces in contact with meat. Thirty-one pigs were identified as carriers of Salmonella in lymph nodes and/or colon content, but of these, only 8 carcasses were positive. A total of 103 Salmonella isolates were serotyped and genotyped. Eight different serotypes were detected; the most common were S. Derby (44/103, 42.7%) and S. Typhimurium (24/103, 23.3%). The most prevalent S. Typhimurium phage type was DT193. Thirty-two isolates were found to be resistant to more than one antimicrobial (MDR). Pulse-field gel electrophoresis (PFGE) permitted the resolution of XbaI macrorestriction fragments of the Salmonella strains into 20 distinct pulsotypes. Combined application of a plasmid profiling assay (PPA) and PFGE gave useful additional information to assist in tracing the routes of Salmonella contamination in abattoirs. To reduce Salmonella prevalence some preventive measures should be encouraged: the origin of infected slaughter animals should be identified and direct and cross-contamination of carcasses should be avoided by adhering to HACCP principles in association with good hygiene procedures (GHP).     

Influence of cell surface hydrophobicity on attachment of Campylobacter to abiotic surfaces

This work aimed to investigate the influence of physicochemical properties and prior mode of growth (planktonic or sessile culture) on attachment of 13 Campylobacter jejuni strains and 5 Campylobacter coli strains isolated from chicken samples to three abiotic surfaces: stainless steel, glass and polyurethane. Water contact angle and zeta potential measurements indicated that the strains varied with respect to surface hydrophobicity (17.6 ± 1.5 to 53.0 ± 2.3°) and surface charge (−3.3 ± 0.4 to −15.1 ± 0.5 mV). Individual strains had different attachment abilities to stainless steel and glass (3.79 ± 0.16 to 5.45 ± 0.08 log cell cm⁻²) but did not attach to polyurethane, with one exception. Attachment of Campylobacter to abiotic surfaces significantly correlated with cell surface hydrophobicity (P ≤ 0.007), but not with surface charge (P ≥ 0.507). Cells grown as planktonic and sessile culture generally differed significantly from each other with respect to hydrophobicity and attachment (P < 0.05), but not with respect to surface charge (P > 0.05). Principal component analysis (PCA) clustered strains into three groups (planktonic culture) and two groups (sessile culture) representing those with similar hydrophobicity and attachment. Of the four highly hydrophobic and adherent strains, three were C. coli suggesting that isolates with greater hydrophobicity and adherence may occur more frequently among C. coli than C. jejuni strains although this requires further investigation using a larger number of strains. Assignment of pulsed-field gel electrophoresis profiles to PCA groups using Jackknife analysis revealed no overall relationship between bacterial genotypes and bacterial attachment. No relationship between serotype distribution and bacterial attachment was apparent in this study.     

Consumption of raw vegetables and fruits: a risk factor for Campylobacter infections

The purpose of this study was to determine the prevalence of Campylobacter in fresh vegetables and fruits at retail level in the Netherlands, and to estimate its implications on the importance of vegetables and fruits as risk factor for campylobacteriosis.Thirteen of the 5640 vegetable and fruit samples were Campylobacter positive, resulting in a prevalence of 0.23% (95% confidence interval (Cl): 0.12-0.39%). The prevalence of packaged products (0.36%, 95% Cl: 0.17-0.66) was significantly higher than of unpackaged products (0.07; 95% Cl: 0.01-0.27). No statistical differences were found between seasons.Combining the mean prevalence found in this study with data on the consumption of vegetables and fruits, an exposure of 0.0048 campylobacters ingested per person per day in the Netherlands by transmission via vegetables and fruits, was calculated. This exposure, as input in a Beta-Poisson dose-response model, resulted in an estimated number of 5.3 × 10⁵ cases of infection with Campylobacter per year for the whole Dutch population. This constitutes the consumption of raw vegetables and fruits, especially when packaged, to be a risk factor for Campylobacter infections.     

Detection and characterization of Salmonella in lairage, on pig carcasses and intestines in five slaughterhouses

In this study, conducted at five slaughterhouses, individual pigs were sampled and followed up from stunning to cooling down of the carcasses. In this way, Salmonella prevalence and possible risk points were described. At the lairage area, pens were sampled using overshoes. At stunning and bleeding, pigs were individually identified and subsequently swabs were taken of the oral cavity and the carcass after polishing, splitting and forced chilling. Additionally, duodenum, ileum, rectum and mesenteric lymph nodes were extracted and samples were taken of the scalding water. All samples were submitted to Salmonella isolation and Salmonella isolates were serotyped and genotyped by pulsed-field gel electrophoresis (PFGE). Of all samples taken (n = 1953), 14.1% were Salmonella positive. The prevalence of S. in the lairage area varied widely (from 0 to 100%) between the slaughterhouses. Of the sampled pigs (n = 226), 48.2% were positive in at least one sample. Statistical analysis revealed that the contamination of the lairage area was related to a higher amount of positive carcasses after polishing. Furthermore, the contamination of the carcasses after splitting and forced chilling was related to the contamination level of the carcass after polishing. A relation between the outer (carcass) contamination and the inner (gut content and lymph nodes) contamination of a pig could not be established. The predominant serotypes were S. Typhimurium (58.7%) and S. Derby (17.4%). Genotyping revealed 46 different PFGE profiles among the 276 Salmonella isolates. The same genotype at the lairage area as in the oral cavity of the pigs was found in 95%. The results indicate that the lairage area is a primary source of Salmonella in slaughter pigs and that carcass contamination originates from the environment rather than from the pig (inner contamination) itself. It further shows that slaughterhouses vary in their capability of dealing with Salmonella positive pigs. A slaughterhouse specific approach is needed, however, general guidelines should be provided to decrease the contamination level of the lairage area and the slaughter environment.