Source attribution at the food sub-product level for the development of the Canadian Food Inspection Agency risk assessment model.

Decreasing the health burden caused by foodborne pathogens is challenging and it depends on the identification of the most significant hazards and food sources causing illnesses, so adequate mitigation strategies can be implemented. In this regard, the Canadian Food Inspection Agency (CFIA) has developed the Establishment-based Risk Assessment (ERA) model, so that a more effective and efficient allocation of resources can be assigned to the highest food safety risk areas. To assess risk, the model considers the type of food sub-products being manufactured by establishments and its scope is limited to the 17 most important foodborne pathogens representing the highest level of food safety risk. However, the information on source attribution at the sub-product level based on a structured approach is limited. To overcome this challenge, an expert elicitation was conducted in 2016 to estimate the relative contribution and associated certainty of each sub-product for 31 pathogen-commodity combinations to the total Canadian health burden associated with foodborne illnesses (expressed in DALYs). These DALYs represent 78% of the total Canadian health burden associated with federally-regulated food commodities considered within the model. A total of 49 Canadian experts recruited using a "snow ball" sampling strategy participated in the study by completing an electronic survey. Results of the elicitation displayed variable levels of health burden allocation between the pathogens and the different commodity sub-products. Assessment of the certainty levels showed some combinations being evaluated with more confidence (e.g., Campylobacter and eggs/poultry sub-products) than others, where a bimodal distribution of certainty was observed (e.g., Toxoplasma in pork sub-products). Furthermore, no participant raised concerns on the food classification scheme, suggesting their agreement with the proposed sub-products categorization of the elicitation. Relative contribution estimates will be included in the CFIA ERA model and used to enhance its applicability for risk prioritization and effective resource allocation during food establishment inspections. While substantial uncertainty around the central tendency estimates was found, these estimates provide a good basis for regulatory oversight and public health policy.

Proximity to Other Commercial Turkey Farms Affects Colonization Onset, Genotypes, and Antimicrobial Resistance Profiles of Campylobacter spp. in Turkeys: Suggestive Evidence from a Paired-Farm Model.

Campylobacter is a leading foodborne pathogen, and poultry products are major vehicles for human disease. However, determinants impacting Campylobacter colonization in poultry remain poorly understood, especially with turkeys. Here, we used a paired-farm design to concurrently investigate Campylobacter colonization and strain types in two turkey breeds (Hybrid and Nicholas) at two farms in eastern North Carolina. One farm (the Teaching Animal Unit [TAU]) was a university teaching unit at least 40 km from commercial turkey farms, while the other (SIB) was a commercial farm in an area with a high density of turkey farms. Day-old birds were obtained from the same breeder flock and hatchery and placed at TAU and SIB on the same day. Birds were marked to identify turkey breed and then commingled on each farm. TAU birds became colonized 1 week later than SIB and had lower initial Campylobacter levels in the cecum. Interestingly, Campylobacter genotypes and antimicrobial resistance profiles differed markedly between the farms. Most TAU isolates were resistant only to tetracycline, whereas multidrug-resistant isolates predominated at SIB. Multilocus sequence typing revealed that no Campylobacter genotypes were shared between TAU and SIB. A bovine-associated genotype (sequence type 1068 [ST1068]) predominated in Campylobacter coli from TAU, while SIB isolates had genotypes commonly encountered in commercial turkey production in the region. One multidrug-resistant Campylobacter jejuni strain (ST1839) showed significant association with one of the two turkey breeds. The findings highlight the need to further characterize the impact of farm-specific factors and host genetics on antimicrobial resistance and genotypes of C. jejuni and C. coli that colonize turkeys.IMPORTANCE Colonization of poultry with Campylobacter at the farm level is complex, poorly understood, and critically linked to contamination of poultry products, which is known to constitute a leading risk factor for human campylobacteriosis. Here, we investigated the use of a paired-farm design under standard production conditions and in the absence of experimental inoculations to assess potential impacts of farm and host genetics on prevalence, antimicrobial resistance and genotypes of Campylobacter in commercial turkeys of two different breeds. Data suggest impacts of farm proximity to other commercial turkey farms on the onset of colonization, genotypes, and antimicrobial resistance profiles of Campylobacter colonizing the birds. Furthermore, the significant association of a specific multidrug-resistant Campylobacter jejuni strain with turkeys of one breed suggests colonization partnerships at the Campylobacter strain-turkey breed level. The study design avoids potential pitfalls associated with experimental inoculations, providing novel insights into the dynamics of turkey colonization with Campylobacter in actual farm ecosystems.

When Are Qualitative Testing Results Sufficient To Predict a Reduction in Illnesses in a Microbiological Food Safety Risk Assessment?

Process models that include the myriad pathways that pathogen-contaminated food may traverse before consumption and the dose-response function to relate exposure to likelihood of illness may represent a "gold standard" for quantitative microbial risk assessment. Nevertheless, simplifications that rely on measuring the change in contamination occurrence of a raw food at the end of production may provide reasonable approximations of the effects measured by a process model. In this study, we parameterized three process models representing different product-pathogen pairs (i.e., chicken-Salmonella, chicken-Campylobacter, and beef-E. coli O157:H7) to compare with predictions based on qualitative testing of the raw product before consideration of mixing, partitioning, growth, attenuation, or dose-response processes. The results reveal that reductions in prevalence generated from qualitative testing of raw finished product usually underestimate the reduction in likelihood of illness for a population of consumers. Qualitative microbial testing results depend on the test's limit of detection. The negative bias is greater for limits of detection that are closer to the center of the contamination distribution and becomes less as the limit of detection is moved further into the right tail of the distribution. Nevertheless, a positive bias can result when the limit of detection refers to very high contamination levels. Changes in these high levels translate to larger consumed doses for which the slope of the dose-response function is smaller compared with the larger slope associated with smaller doses. Consequently, in these cases, a proportional reduction in prevalence of contamination results in a less than proportional reduction in probability of illness. The magnitudes of the biases are generally less for nonscalar (versus scalar) adjustments to the distribution.

Determining the health benefits of poultry industry compliance measures: the case of campylobacteriosis regulation in New Zealand.

I undertake a cost benefit analysis of the food safety regulation of production of poultry for the New Zealand domestic market and the reduction in foodborne illness following this. I take a societal perspective to demonstrate that regulation brings both benefits and costs. I derive a cost of illness (COI) estimate of foodborne campylobacteriosis from three previous studies. I apply a cost benefit analysis (CBA) to this estimate, combined with the cost data supplied by industry and the regulator. The benefit:cost ratio was remarkable, showing a good return from the combined efforts of industry and the regulator in reduction of campylobacteriosis; in dollar terms a gain of at least $57.4 million annually. In summary the study demonstrates the high value to the New Zealand economy of investment in food safety compliance at the primary industry level.

Cost-effectiveness of interventions to control Campylobacter in the New Zealand poultry meat food supply.

An analysis of the cost-effectiveness of interventions to control Campylobacter in the New Zealand poultry supply examined a series of interventions. Effectiveness was evaluated in terms of reduced health burden measured by disability-adjusted life years (DALYs). Costs of implementation were estimated from the value of cost elements, determined by discussions with industry. Benefits were estimated by changing the inputs to a poultry food chain quantitative risk model. Proportional reductions in the number of predicted Campylobacter infections were converted into reductions in the burden of disease measured in DALYs. Cost-effectiveness ratios were calculated for each intervention, as cost per DALY reduction and the ratios compared. The results suggest that the most cost-effective interventions (lowest ratios) are at the primary processing stage. Potential phage-based controls in broiler houses were also highly cost-effective. This study is limited by the ability to quantify costs of implementation and assumptions required to estimate health benefits, but it supports the implementation of interventions at the primary processing stage as providing the greatest quantum of benefit and lowest cost-effectiveness ratios.

Assessment of the prevalence and diversity of emergent campylobacteria in human stool samples using a combination of traditional and molecular methods.

This study aims to assess the diversity of campylobacteria (Campylobacter and Arcobacter) in human fecal samples from patients with diarrhea (n = 140) and asymptomatic controls (n = 116) in Chile, using a combination of traditional culture and molecular methods. The culture methods detected campylobacteria in 10.7% of the patients with diarrhea and in 1.7% of the controls. In contrast, the molecular methods detected campylobacteria more often than the traditional culture, with a prevalence of 25.7% and 5.2%, respectively. The traditional methods only recovered the species Campylobacter jejuni, Campylobacter coli, and Arcobacter butzleri, whereas the molecular methods additionally detected the emergent species Campylobacter concisus and Campylobacter ureolyticus.

Importance of the producer on retail broiler meat product contamination with Campylobacter spp.

BACKGROUND: Campylobacter spp. are a leading cause of human bacterial gastroenteritis worldwide, with poultry meat being considered the most important source of the infection. To obtain data on broiler meat contamination with Campylobacter spp. in Lithuania, the occurrence, counts and genotypes of these pathogens on raw broiler meat products from different producers were examined. RESULTS: Out of 312 broiler meat product samples examined, 46.8% were contaminated with Campylobacter spp. Campylobacter jejuni was identified in 51.4% and Campylobacter coli in 37.7% of positive samples. Campylobacter jejuni was more frequently found in the warm period (April-October) and C. coli in the cold period (November-March) of the year (P < 0.05). The overall mean count of Campylobacter spp. was 3.55 and 3.50 log10 colony-forming units (CFU) on wings and drumsticks respectively. The occurrence and counts of Campylobacter spp. varied significantly between producers examined (P < 0.05). Analysis of flaA-RFLP genotyping revealed C. jejuni genotypes common to all producers as well as producer-specific genotypes. CONCLUSION: Both the occurrence and counts of Campylobacter spp. on broiler meat products were producer-dependent, so this should be kept in mind when risk-based control measures at national level are applied.

Quantitative risk assessment of human campylobacteriosis by consumption of salad cross-contaminated with thermophilic Campylobacter spp. from broiler meat in Argentina.

Here, we developed a quantitative risk assessment for thermophilic Campylobacter spp. related to the consumption of salad prepared alongside broiler meat. The assessment considered initial contamination levels, cross-contamination and decontamination events during the broiler slaughter process and distribution, and storage and consumption patterns in Argentina and other Latin American countries. The model predicted an infection risk of 3.32×10(-4) per serving. This estimation was variable according to the dose-response model used. Considering the number of chickens slaughtered annually in Argentina, the estimated number of people who could suffer campylobacteriosis related to poultry meat consumption was, on average, 484,304. The risk of human campylobacteriosis was most sensitive to the probability of infection from a Campylobacter (r=0.72), the number of Campylobacter spp. per serving (r=0.40), the frequency of washing the cutting board (r=-0.31), the preparation of raw poultry before salad using the same cutting board (r=0.14), and the frequency of hand washing (r=-0.14). The most sensitive stages of the process identified through the risk assessment can be used as a basis for measures of risk management. Public campaigns on hygiene habits during food preparation at home should focus on the importance of washing the cutting board before preparing raw and ready-to-eat foods and of washing the hands during food preparation.

A simplified and cost-effective enrichment protocol for the isolation of Campylobacter spp. from retail broiler meat without microaerobic incubation.

BACKGROUND: To simplify the methodology for the isolation of Campylobacter spp. from retail broiler meat, we evaluated 108 samples (breasts and thighs) using an unpaired sample design. The enrichment broths were incubated under aerobic conditions (subsamples A) and for comparison under microaerobic conditions (subsamples M) as recommended by current reference protocols. Sensors were used to measure the dissolved oxygen (DO) in the broth and the percentage of oxygen (O2) in the head space of the bags used for enrichment. Campylobacter isolates were identified with multiplex PCR assays and typed using pulsed-field gel electrophoresis (PFGE). Ribosomal intergenic spacer analyses (RISA) and denaturing gradient gel electrophoresis (DGGE) were used to study the bacterial communities of subsamples M and A after 48 h enrichment. RESULTS: The number of Campylobacter positive subsamples were similar for A and M when all samples were combined (P = 0.81) and when samples were analyzed by product (breast: P = 0.75; thigh: P = 1.00). Oxygen sensors showed that DO values in the broth were around 6 ppm and O2 values in the head space were 14-16% throughout incubation. PFGE demonstrated high genomic similarity of isolates in the majority of the samples in which isolates were obtained from subsamples A and M. RISA and DGGE results showed a large variability in the bacterial populations that could be attributed to sample-to-sample variations and not enrichment conditions (aerobic or microaerobic). These data also suggested that current sampling protocols are not optimized to determine the true number of Campylobacter positive samples in retail boiler meat. CONCLUSIONS: Decreased DO in enrichment broths is naturally achieved. This simplified, cost-effective enrichment protocol with aerobic incubation could be incorporated into reference methods for the isolation of Campylobacter spp. from retail broiler meat.

Economics of reducing Campylobacter at different levels within the Belgian poultry meat chain.

Campylobacter infections pose a serious public health problem in Belgium. Poultry meat is most likely responsible for 40% of human campylobacteriosis cases in Belgium. On a yearly basis, consumption of poultry meat causes at least 22,000 campylobacteriosis cases, with a cost of illness of Euro 10.9 million. Several intervention measures have been proposed in literature, aiming to reduce the contamination of poultry meat and thus lead to significant reductions of human campylobacteriosis cases. This study aimed to evaluate the cost-benefit ratio, i.e., the ratio of reduced costs of illness on intervention costs of various intervention measures. These measures were selected by representatives from the poultry meat sector and experts in the field of poultry science. The selection comprised measures at the farm level (phage therapy), at the processing plant (spraying of carcasses with lactic acid or electrolyzed oxidizing water, crust freezing, or irradiation), and at the consumer level (improving kitchen hygiene and application of home freezing). Among these measures, the decontamination of carcasses with electrolyzed oxidizing water applied in the processing plant was the most efficient (17.66), followed by the use of lactic acid (4.06). In addition, phage therapy generated a positive cost-benefit ratio (2.54). Irradiation indicated the highest efficacy, but its cost-benefit ratio was rather low (0.31). There seems to be less gain by trying to improve food handling in the kitchen. The cost to reach consumers is large, while only a very limited fraction of the consumers is willing to change its behavior. The outcome of this study poses valuable information for future risk-management decisions in Belgium.

Quantitative risk assessment of thermophilic Campylobacter spp. and cross-contamination during handling of raw broiler chickens evaluating strategies at the producer level to reduce human campylobacteriosis in Sweden.

Campylobacter is a major bacterial cause of infectious diarrheal illness in Sweden and in many other countries. Handling and consumption of chicken has been identified as important risk factors. The purpose of the present study was to use data from a national baseline study of thermophilic Campylobacter spp. in raw Swedish broiler chickens in order to evaluate some risk management strategies and the frequency of consumer mishandling, i.e., handling leading to possible cross-contamination. A probabilistic model describing variability but not uncertainty was developed in Excel and @Risk. The output of the model was the probability of illness per handling if the chicken was mishandled. Uncertainty was evaluated by performing repeated simulations and substituting model parameters, distributions and software (Analytica). The effect of uncertainty was within a factor of 3.2 compared to the baseline scenario. For Campylobacter spp. prevalence but not concentration, there was a one-to-one relation with risk. The effect of a 100-fold reduction in the levels of Campylobacter spp. on raw chicken reduced the risk by a factor of 12 (fresh chicken) to 30 (frozen chicken). Highly-contaminated carcasses contributed most to risk and it was estimated that by limiting the contamination to less than 4 log CFU per carcass, the risk would be reduced to less than 17% of the baseline scenario. Diverting all positive flocks to freezing was estimated to result in 43% as many cases as the baseline. The second best diversion option (54% of baseline cases) was to direct all chickens from the two worst groups of producers, in terms of percentages of positive flocks delivered, to freezing. The improvement of using diverting was estimated to correspond to between 5 to 767 fewer reported cases for the different strategies depending on the assumptions of the proportion of reported cases (1 to 50%) caused by Campylobacter spp. from Swedish chicken. The estimated proportion of consumer mishandlings sufficient to explain 1 to 50% of the reported campylobacteriosis cases was 0.005-0.25%, or taking estimated underreporting into consideration, was 0.05-2.6%. The strategy of using a diversion treatment, e.g., freezing, based on the past performance of producers was promising, but needs to be evaluated further. Although challenging, consumer education has a great potential given the direct relation between behaviour and risk. However, any improvements following implementation of these strategies may be hard to detect if less than 50% of reported cases are exposed via chicken and the cross-contamination route.

Effect of acidified sodium chlorite treatment on chicken carcases processed in South Australia.

A trial on the effectiveness of acidified sodium chlorite (ASC) on Salmonella and Campylobacter was undertaken on chicken carcases after they exited the screw chiller of a commercial premises in Adelaide, Australia. On untreated carcases mean log10 total viable count (25 degrees C) was 2.78/cm2 compared with 1.23/cm2 on treated carcases. Prevalence of E. coli, Salmonella and Campylobacter was 100%, 90% and 100% respectively, on untreated carcases and 13%, 10% and 23% respectively, on treated carcases. The distributions of E. coli, Salmonella and Campylobacter (mean log10 of positive samples) from untreated carcases were 1.55, -1.80 and 1.59/cm2 respectively, and -0.64, -1.85 and -2.21/cm2 respectively, on treated carcases. On untreated carcases S. Sofia and S. Infantis were isolated from 73% and 37% of carcases, respectively; only S. Sofia was isolated from treated carcases. The significant reductions in both prevalence and concentration demonstrated in the present trial indicate that ASC is a risk management option immediately available to the poultry industry.

Quantitative risk assessment of Campylobacter spp. in poultry based meat preparations as one of the factors to support the development of risk-based microbiological criteria in Belgium.

The objective of this study was to do an exercise in risk assessment on Campylobacter spp. for poultry based meat preparations in Belgium. This risk assessment was undertaken on the demand of the competent national authorities as one of the supportive factors to define risk-based microbiological criteria. The quantitative risk assessment model follows a retail to table approach and is divided in different modules. The contamination of raw chicken meat products (CMPs) was represented by a normal distribution of the natural logarithm of the concentration of Campylobacter spp. (ln[Camp]) in raw CMPs based on data from surveillance programs in Belgium. To analyse the relative impact of reducing the risk of campylobacteriosis associated with a decrease in the Campylobacter contamination level in these types of food products, the model was run for different means and standard deviations of the normal distribution of the ln[Camp] in raw CMPs. The limitation in data for the local situation in Belgium and on this particular product and more precisely the semi-quantitative nature of concentration of Campylobacter spp. due to presence/absence testing, was identified as an important information gap. Also the knowledge on the dose-response relationship of Campylobacter spp. was limited, and therefore three different approaches of dose-response modelling were compared. Two approaches (1 and 2), derived from the same study, showed that the reduction of the mean of the distribution representing the ln[Camp] in raw CMPs is the best approach to reduce the risk of Campylobacter spp. in CMPs. However, for the simulated exposure and approach 3 it was observed that the reduction of the standard deviation is the most appropriate technique to lower the risk of campylobacteriosis. Since the dose-response models used in approach 1 and 2 are based on limited data and the reduction of the mean corresponds with a complete shift of the contamination level of raw CMPs, demanding high efforts from the poultry industry, it is proposed to lower the standard deviation of the concentration of Campylobacter spp. in raw CMPs. This proposal corresponds with the elimination of the products that are highly contaminated. Simulation showed that eating raw chicken meat products can give rise to exposures that are 10(10) times higher than when the product is heated, indicating that campaigns are important to inform consumers about the necessity of an appropriate heat treatment of these type of food products.

[Dose-response-models and their implications for quantitative risk assessment for Campylobacter infections]. / Dosis-Wirkungsmodelle und ihre Implikationen im Rahmen einer quantitativen Risikoabschätzung für Campylobacter-Infektionen.

For some time now there have been several projects dealing with the assessment of campylobacteriosis risks for consumers. Dose-response relationships form a crucial part of such assessments, as they specify disease probabilities depending on different microbial concentrations in foods. Evaluation of such models, however, is difficult because of problems to find data on which reliable assumptions could be based. Ongoing risk analyses for Campylobacter mainly refer to a single administration study with human volunteers published by Black et al. (1988). However, whether results from this study can be transferred to target populations envisaged in risk assessments remains questionable for several reasons. In this paper some alternative dose-response models, their fit to the data of Black et al., and risk estimates resulting in a fictitious scenario are discussed and compared. Depending on the dose-response model assumed risk estimates can differ remarkably. Therefore it is hardly possible to make reliable quantifications of risks in reality, however, it can be determined how much they may vary assuming different scenarios.

The clinical relevance of microbiologic testing: a comparative analysis of microbiologic samples secured from the same sites and cultured in two independent laboratories.

A field study using five different private periodontal practices was conducted; it compared two microbiologic culture samples simultaneously secured from the same sites within 23 individual patients and submitted for bacterial identification and antibiotic sensitivity testing to two separate laboratories. The results from the two laboratories were often different. In no instance did both laboratories agree on the presence of identical bacterial species. When only bacteria above threshold levels were compared, agreement was found in only nine of 23 cases. When examining antibiotic sensitivity, using 100% kill of all tested pathogens as the ideal, agreement between the two laboratories was poor. The laboratories agreed on the use of amoxicillin 17% of the time, tetracycline 26% of the time, and metronidazole 48% of the time. The use of amoxicillin and metronidazole in combination yielded a 78% agreement when the results of both laboratories were combined. It would appear from the data that the empirical use of amoxicillin-metronidazole combination therapy may be more clinically sound and cost effective than culturing and antibiotic selection based on the results of culture from any single microbiologic testing laboratory.