Microbiological Risk Assessment Research Articles

‘MicroHibro’: A software tool for predictive microbiology and microbial risk assessment in foods

A tool able to quantitatively assess the fate of potential pathogenic microorganisms in foods along the food chain and their impact on public health is highly valuable for food safety decision-makers. The aim of this work was to present an overview of the Predictive Microbiology software MicroHibro, which is able to assess the evolution of potential pathogens and spoilage microorganisms along the food chain, providing estimates for the exposure level and risk associated with a food product. The application is built on an extensive Predictive Microbiology Model Data Base (PMDB) including kinetic processes like growth, inactivation, transfer as well as dose-response models. PMDB can be populated with new models by using an on-line tool in combination with a standardized method for describing Predictive Microbiology models. This enables MicroHibro to be easily updated, increasing its applicability and use. Estimation of microbial risk associated with a food product can be achieved, in MicroHibro, by describing steps in any food chain using four different microbial processes (growth, inactivation, transfer and partitioning). As a result, an estimate of the concentration and prevalence of microorganisms in the food of interest as well as attendant risk are provided. Also, MicroHibro allows comparing different predictive models and validate them by introducing user's data. In this paper, examples are provided to illustrate how predictive models can be incorporated in MicroHibro, and then, used to develop a Quantitative Microbial Risk Assessment model. The use of expert computational systems is a powerful tool for supporting food safety and quality activities by Health Authorities and the food industry. They represent a breakthrough in the assessment and management of food safety based on scientific evidence.

Microbiological risk assessment and simple cost‐effective ways to reduce the risk in bulk food bags manufacturing company

AbstractThis study was conducted to evaluate the microbial risk associated in bulk food bags manufacturing facilities and its cost‐effective way to minimize the risk. Swab samples from each step of manufacturing process was collected and microbiological analysis was done. Results showed that the bulk food bags manufacturing process was grossly contaminated with multiple types of bacteria. Moderate number of total aerobic bacteria (≤3.68 log cfu/unit), coliform (≤3.63 log cfu/unit), fecal coliform (1.0–1.25 log cfu/unit), Staphylococcus spp. count (≤3.6 log cfu/unit) was recorded in worker's hand gloves and different sections of the whole production facility. Although no Escherichia coli or Salmonella spp. was detected, enrichment culture study detected Streptococcus spp., and fecal Streptococcus spp. in some swabs and hand gloves samples. Other than UV treatment alone, washing the hand gloves with calcinated calcium (CCa; 0.02%) followed by drying under UV light, and UV light in finished product storage room, and sanitizing the floor surfaces with 0.02% CCa, was able to significantly reduce (1.0–3.68 log cfu/unit) or eliminate the bacterial contaminants from hand gloves, finished products, and floor surfaces. This simple treatment was seen to minimize the risks of microbial contamination in the bulk food bags manufacturing facilities.Practical applicationsFlexible intermediate bulk containers (FIBCs) are used by various industrial sectors like agriculture, chemicals, and pharmaceutical, but one of the largest users of FIBC bags is the food industry. Transporting and storing food is tougher to do than any other product. The food companies are constantly in search of ways to maximize profits while cutting costs and conserving space. FIBC bags have helped thousands of businesses around the world to achieve this goal. On the other hand, reducing risks from microbial contamination is an essential part of every food manufacturer's responsibility to protect both its customers and its business. The cost‐effective and simple methods described in this study will be applicable in the bulk food bags manufacturing facilities worldwide to ensure the quality and safety of the food.

Combination of Multilocus Sequence Typing and GS-PCR Reveals an Association of Pandemic Vibrio parahaemolyticus Clone with Clinical and Seafood Isolates.

Pandemic V. parahaemolyticus isolates have become a serious public health concern. This study demonstrated the characteristics of clinical and seafood V. parahaemolyticus isolates, and determined the phylogenetic relatedness among them. These results can be used for microbiological risk assessment in China.

Microbiological Risk Assessment and Bioprocess Engineering

Abstract The Europe 2020 strategy (European Commission, 2010) calls a bioeconomy as a key element for smart and green growth in Europe. The development of a greener and more resource-efficient economy gives rise to new technologies and materials, which in turn may result in increased exposure to biological agents or combinations of different potentially harmful factors. For example, the expanding recycling industry employs an increasing number of workers which have to face various health problems (pulmonary, gastrointestinal and skin problems) as a result of exposure to biological agents such as airborne microorganisms. However, specific numbers for occupational diseases in this sector are still lacking. There are various workplaces and professional activities especially from the green industry for which exposure to microbiological agents occur unexpectedly and in an uncontrolled way. The issue of uncontrolled microbial exposure there is for example in waste treatment and for retrofitting activities, both growing sectors of employment in a greening society. As a result of the problem in the green industrial sector, there is a need to develop tools for risk assessment and prevention measures. In order to be able to develop suitable risk management strategies, a further development of detection and identification methods for biological agents is needed to cover the whole spectrum of microorganisms. the present paper focuses on the microbiological risk assessment in the context of the development of new and safe industrial products and processes of green industry (bioindustry and bioprocessing).

Application of data science in risk assessment and early warning.

The currently applied approaches, procedures and tools used for the identification of emerging risks vary greatly among Member States of the EU. EFSA established a structured approach for emerging risk identification that mainly consists of systematically searching, collecting, collating and analysing information and data. In addition, EFSA concluded that new methodologies and tools are needed to facilitate efficient and transparent sharing of data, knowledge and methods in the field of emerging risk identification between Member States. As the result of an open call issued by EFSA, the ‘Determination and metrics of emerging risks’ (DEMETER) project was established in spring 2017 to support current and future procedures for identification of emerging risks. As the Bundesinstitut für Risikobewertung (BfR) hosting site is involved in the DEMETER project, as well as in several other software development activities in the area of quantitative microbiological risk assessment, the fellow had the opportunity to play an active role in the project work and development of the running DEMETER project. The training and close integration in the project team enabled the fellow to make significant contributions, e.g. with the creation of new open source data processing workflows and by contributing to the Emerging Risk Knowledge Exchange Platform (ERKEP) Framework Concept Note. Besides DEMETER, the fellow participated in other activities of the Unit for Food Technologies, Supply Chains and Food Defence, including testing and applying several BfR open source software tools which had been developed in previous projects and that are used in microbiological risk assessment (e.g. Predictive Microbial Modelling Lab (PMM‐Lab)) or as automatic data retrieval systems (e.g. SiLeBAT NewsRadar) – see https://foodrisklabs.bfr.bund.de.

Modelling of inactivation through heating for quantitative microbiological risk assessment (QMRA).

EFSA regards the household as a stage in the food chain that is important for the final number of food‐borne infections. The fate of a pathogen in the private kitchen largely depends on consumer hygiene during preparation of food and on its proper cooking, especially in the case of meat. Unfortunately, detailed information on the microbiological survival in meat products after heating in the consumer kitchen is lacking. The aim of the study was to improve the estimation of the inactivating effect on pathogens by heating meat or a meat product by the consumer in the kitchen. On that account, artificially contaminated meat and meat products were cooked according to several degrees of doneness and simulating real world conditions, and bacterial survival was measured. Heat camera pictures and button temperature loggers inserted into the food matrix served to record time and the temperature of heating. Temperature, time and the microbial survival ratio observed served to inform a mathematical model able to explain the thermal inactivation of meat or a meat product in home settings. The results of the study would help to improve microbiological comparative exposure assessments of pathogens in food, as an attribution tool and as a supportive tool for risk‐based sampling in monitoring and surveillance.

Risk ranking of chemical and microbiological hazards in food.

Risk ranking is a versatile tool used to prioritise activities performed by public health regulatory bodies. It also allows efficient communication between all stakeholders in the process of risk analysis. However, risk ranking methods are still not optimal. Because of the different approaches employed in the risk assessment of microbiological agents and chemicals, it is difficult to rank them together using the same metrics. In our work, we first discuss differences and commonalities between chemical and microbiological risk assessment to provide a starting point for consideration of a common risk ranking platform. In the second part, we perform risk ranking of contaminants and regulated chemicals using the recently developed Risk Thermometer tool. In this approach, chemicals are not ranked solely on the basis of the margin of exposure between a reference value and the exposure, but also by considering the severity of the critical health effects used. The results show that ranking using both methods provides different results from the use of either method alone. Overall, specific chemical groups (i.e. heavy metals, pesticides, etc.) do not generally rank higher or lower, but individual compounds are scattered in the rankings from low to high. Risk ranking methods demand further development to gain wide acceptability and recognition.

Next generation quantitative microbiological risk assessment: Refinement of the cold smoked salmon-related listeriosis risk model by integrating genomic data

Recent developments in genome sequencing open new opportunities for explaining the intraspecific variability of phenotypes (e.g. virulence, growth behavior). Successful association between WGS-data and specific phenotypes is thought to contribute to better predicting microbial behaviors. Implementing this information in hazard identification, exposure assessment, and hazard characterization processes will refine quantitative microbial risk assessments (QMRA) models. The aim of this study was to explore the refinements in QMRA studies when considering phenogenotype associations for the hazard properties, particularly related to the growth ability at low temperature (minimal growth temperature, Tmin) and the virulence. The used QMRA-model was previously developed for the assessment of the number of listeriosis cases associated to cold-smoked salmon in France. The global prevalence in the existing model was replaced by the specific prevalence for each genotypic subgroup (clonal complex - CC) in Europe. In order to describe the variability of Listeria monocytogenes’ growth characteristics more accurately, two different distributions of Tmin were implemented. For risk characterization, three different groups of virulence were considered according to the CCs. Each group was associated with a specific dose-response model. The new QMRA model showed that CCs contributing the most in consumer exposure were not those that contributed the most to listeriosis cases. The most prevailing CCs led to few listeriosis cases, whereas uncommon high virulent strains were responsible for the majority of predicted cases. Similarly, the less prevailing group of strains with high Tmin was approximately two times less implicated when considering human listeriosis in comparison to food contamination. Considering genotypic data in QMRA opens the way for the establishment of risk based measures specific to distinct sub-groups of L. monocytogenes.

Quantitative Microbiological Risk Assessment: Underrated Tool in Process Improvement in Food Microbiology

Quantitative Microbiological Risk Assessment: Underrated Tool in Process Improvement in Food Microbiology

Harmonized terms, concepts and metadata for microbiological risk assessment models: The basis for knowledge integration and exchange

In the last decades the microbial food safety community has developed a variety of valuable knowledge (e.g., mathematical models and data) and resources (e.g., databases and software tools) in the areas of quantitative microbial risk assessment (QMRA) and predictive microbiology. However, the reusability of this knowledge and the exchange of information between resources are currently difficult and time consuming. This problem has increased over time due to the lack of harmonized data format and rules for knowledge annotation. It includes the lack of a common understanding of basic terms and concepts and of a harmonized information exchange format to describe and annotate knowledge. The existence of ambiguities and inconsistencies in the use of terms and concepts in the QMRA and predictive microbial (PM) modelling necessitates a consensus on their refinement, which will allow a harmonized exchange of information within these areas. Therefore, this work aims to harmonize terms and concepts used in QMRA and PM modelling spanning from high level concepts as defined by Codex Alimentarius, Food and Agriculture Organization (FAO) and World Health Organization (WHO), up to terms generally used in statistics or data and software science. As a result, a harmonized schema for metadata that allows consistent annotation of data and models from these two domains is proposed. This metadata schema is also a key component of the Food Safety Knowledge Markup Language (FSK-ML), a harmonized format for information exchange between resources in the QMRA and PM modelling domain. This work is carried out within a research project that aims to establish a new community resource called Risk Assessment Modelling and Knowledge Integration Platform (RAKIP). This platform will facilitate the sharing and execution of curated QMRA and PM models using the foundation of the proposed harmonized metadata schema and information exchange format. Furthermore, it will also provide access to related open source software libraries, converter tools and software-specific import and export functions that promote the adoption of FSK-ML by the microbial food safety community. In the future, these resources will hopefully promote both the knowledge reusability and the high-quality information exchange between stakeholders within the areas of QMRA and PM modelling worldwide.

Microbiological Quality and Risk Assessment for Aflatoxins in Groundnuts and Roasted Cashew Nuts Meant for Human Consumption.

Nuts are one of the commonly consumed snacks but poor handling and storage practices can make them prone to foodborne infections. The study aimed at assessing the microbiological quality and risk assessment for aflatoxins in groundnuts and cashew nuts consumed in selected locations in Nigeria. The moisture content, colony counts, incidence of pathogenic bacteria, aflatoxin contamination, and risk assessment for aflatoxins were evaluated using standard methods. The moisture content and total viable count ranged from 5.00–8.60% and 5.5–89 × 103 cfug−1, respectively, while the fungal count was between 4–24 × 103 and 1.0–4.5 × 102 cfug−1, respectively. Eleven fungal species belonging to 5 genera were isolated from the nuts, with Aspergillus flavus, Rhizopus oryzae, and Fusarium oxysporum having the highest percentage occurrence of 50%. In addition, the aflatoxin concentration ranged 0.1–6.8 and 29–33.78 ng kg−1 for cashew nuts and groundnuts, respectively. The margin of exposure (MOE) to aflatoxin contamination was 6.10 for groundnuts and 1000 for cashew nuts and the nuts consumers were at a risk of exposure to foodborne diseases and aflatoxin contamination with mean exposure values of 27.96 and 0.17 ng kg−1bwday−1, respectively. The risk of primary liver cancer for groundnuts and cashew nuts consumers was also estimated to be 1.38 and 0.01 canceryear−1100,000−1person, respectively. This calls for mitigation measures from appropriate governmental organizations.

Assessing Disaster-Related Health Risk: Appraisal for Prevention.

Risk assessment is a key component of public health interventions intended to prevent or reduce adverse health effects. Health risk assessments are widely used to guide public health programming, as well as multi-sectoral studies of environmental impact and developmental decision making. Analytical risk assessment is a well-validated tool that is routinely used among certain subsets of public health, including those for chemical, radiological, and microbiological risk assessment. However, this is not the case for risk assessments involving disasters in general, or more specifically, for public health emergencies involving environmental hazards (eg, technological, hydro-meteorological, and seismic).There remains a need for a reproducible, well-validated, disaster-related health risk assessment process that is suitable for accommodating the current gaps in certainty. This report is intended to offer a practical framework and nomenclature for assessing disaster-related health risk that is: (1) accurate; (2) based upon historical evidence; (3) quantifiable in public health terms; and (4) inclusive of uncertainty. KeimM. Assessing disaster-related health risk: appraisal for prevention. Prehosp Disaster Med. 2018;33(3):317-325.

Microbiological Assessment of Raw Meat Used in Fast-Food Products Sold for Public Consumption

Raw meat contains sufficient nutrients to support microbial growth and because of that the proper surveillance of the meat products destined for public consumption is mandatory. The purpose of this study was to conduct a microbiological risk assessment regarding the safety of pork, chicken and beef meat products found in fast –food units from Transylvania area. One hundred and seventy samples of raw meat(n=35) and fried foods made of pork(n=39), chicken(n=45)and beef products(n=51) were purchased randomly from 5 different fast-food units located in the study area.The determination performed in order to assess the safety was the total number of Enterobacteriaceae, evaluation of toxigenic E. coli and Salmonella spp. presence, which is also the parameter requested by the current regulation. The levels of contamination with Enterobacteriaceae that exceeded the current legislation limit were 6/39 (15%), 6/45 (13%) and 5/51 (9%) in cooked pork, chicken and respectively beef meat. Given the similar rate of contaminations among these three categories of food there were no statistical differences noticed (p>0.05). Results showed that in 35 of 170 (20%) collected food samples were found total Enterobacteriaceae count over 3 log CFU/g and 12 of 170 (7%) were found with coliform bacteria. Raw meat destined for fast-food industry can represent a risk for public health if hygiene and refrigerating conditions are not properly monitored.

Isolation of Shiga toxin-producing strains of Escherichia coli from beef and swine carcasses and the characterization of their genes

Escherichia coli is part of the normal microflora of the intestinal tract of humans and warm-blooded animals, but its presence in raw material and food of animal origin is considered as fecal contamination and can be very dangerous for consumers. The determination of the number of E. coli in raw material and food is important because among them can be pathogenic strains. The most dangerous strains are considered enterohemorrhagic E. coli as a causative agent of severe bloody diarrhea and hemorrhagic uremic syndrome in humans through the production of Shiga-toxin, which is the main virulence factor, responsible for disease. The aim of this study was to identify the prevalence of Shiga toxin-producing strains of E. coli (STEC) from swabs of beef and swine carcass in slaughterhouses in Ukraine and characterize their genes, which are responsible for pathogenic properties. A total of 230 samples of swabs from beef (130) and swine (100) carcasses were obtained from 5 slaughterhouses in Ukraine between 2012 and 2015. Samples of swabs from carcasses were randomly selected at the final point of the process after the final washing of the carcass from the following areas: distal hind limb, abdomen (lateral and medial) from swine carcasses, brisket, flank and flank groin areas from beef carcasses. All samples were examined by culture-dependent method, after that each positive isolate of STEC was analyzed by multiplex PCR to detect the stx1, stx2, and eae genes. Out of 230 collected samples, seven (7.2%) were contaminated with STEC. The highest prevalence of STEC was found in swabs from beef carcasses (8.1%) in comparison to swabs from swine carcasses (5.7%). The stx1 gene was the predominant gene detected in all STEC positive samples. The eae gene was found in one of the examined isolates from beef carcass. Three isolates from swabs of beef carcass carried both stx1 and stx2 genes, one isolate showed association between stx1 and eae genes, one isolate was positive for stx1 gene only. In swabs from swine carcasses (2 isolates) stx1 and stx2 genes were presented simultaneously. The results of this study suggested that fresh raw meat could be a potential vehicle for transmission of the Shiga toxin-producing strain of E. coli to humans. This is the first report of STEC prevalence in beef and swine carcasses in Ukraine and these data will be valuable for microbiological risk assessment and help the appropriate services to develop strategies to mitigate health risk.

Enterobacteria associated with houseflies (Musca domestica) as an infection risk indicator in swine production farms

Houseflies (Musca domestica) spend part of their life development on animal or human manure. Manure is high in pathogenic microbes; thus, houseflies have been known as a mechanical vector for various important zoonotic diseases. Therefore, the present study showcases captured houseflies from intensive swine production regions (which are areas of high manure concentration) in Southern Brazil, and analyses their bodies’ to the presence of Escherichia coli and Salmonella sp. and the sensitivity of these bacteria to various antibiotics. Additionally, Quantitative Microbiology Risk Assessment was performed simulating the contamination of lettuce by flies' bacteria and subsequent lettuce consumption by an adult human being. Houseflies were captured in swine buildings and farm houses from five farms. E. coli quantification values ranged from 104 to 106 CFU/20 flies, and all sampling sites had positive results from bacteria presence in the collected houseflies. On the other hand, Salmonella sp. presence was observed in only three farms, where the quantification ranged from 102 to 105 CFU/20 flies. The bacteria showed to be resistant to at least two from the four tested antibiotics (ampicillin, Cefalotin, Ciprofloxacin and Norfloxacin) antibiotics used in human or veterinary medicine. Infection probability analyses showed risk of human infection by E.coli, indicating possible transmission of zoonotic pathogens through flies. In this context, it was possible to conclude that there is a need for flies control, especially in swine farms where zoonotic pathogens can be abundant, to minimize the health impact of the vectorization of enteric bacteria.

Next generation microbiological risk assessment—Potential of omics data for hazard characterisation

According to the World Health Organization estimates in 2015, 600 million people fall ill every year from contaminated food and 420,000 die. Microbial risk assessment (MRA) was developed as a tool to reduce and prevent risks presented by pathogens and/or their toxins. MRA is organized in four steps to analyse information and assist in both designing appropriate control options and implementation of regulatory decisions and programs. Among the four steps, hazard characterisation is performed to establish the probability and severity of a disease outcome, which is determined as function of the dose of toxin and/or pathogen ingested. This dose-response relationship is subject to both variability and uncertainty. The purpose of this review/opinion article is to discuss how Next Generation Omics can impact hazard characterisation and, more precisely, how it can improve our understanding of variability and limit the uncertainty in the dose-response relation. The expansion of omics tools (e.g. genomics, transcriptomics, proteomics and metabolomics) allows for a better understanding of pathogenicity mechanisms and virulence levels of bacterial strains. Detection and identification of virulence genes, comparative genomics, analyses of mRNA and protein levels and the development of biomarkers can help in building a mechanistic dose-response model to predict disease severity. In this respect, systems biology can help to identify critical system characteristics that confer virulence and explain variability between strains. Despite challenges in the integration of omics into risk assessment, some omics methods have already been used by regulatory agencies for hazard identification. Standardized methods, reproducibility and datasets obtained from realistic conditions remain a challenge, and are needed to improve accuracy of hazard characterisation. When these improvements are realized, they will allow the health authorities and government policy makers to prioritize hazards more accurately and thus refine surveillance programs with the collaboration of all stakeholders of the food chain.

Assessing natural mineral water microbiology quality in the absence of cultivable pathogen bacteria

Italian Directives recommend the good quality of natural mineral waters but literature data assert a potential risk from microorganisms colonizing wellsprings and mineral water bottling plants. We evaluated the presence of microorganisms in spring waters (SW) and bottled mineral waters (BMW) samples. Routine microbiological indicators, additional microorganisms like Legionella spp., Nontuberculous mycobacteria (NTM) and amoebae (FLA) were assessed in 24 SW and 10 BMW samples performing cultural and molecular methods. In 33 out of 34 samples, no cultivable bacteria ≥10 CFU/L was found. Cultivable FLA were detected in 50% of water samples. qPCR showed the presence of Legionella qPCR units in 24% of samples (from 1.1 × 102 to 5.8 × 102 qPCR units/L) and NTM qPCR units in 18% of samples (from 1 × 102 to 1 × 105 qPCR units/L). Vermamoeba vermiformis and Acanthamoeba polyphaga were recovered respectively in 70% of BMW samples (counts from 1.3 × 103 to 1.2 × 105 qPCR units/L) and 42% of SW samples (from 1.1 × 103 to 1.3 × 104 qPCR units/L). Vahlkampfia spp. was detected in 42% of SW and 70% of BMW samples (from 1.2 × 103 to 1.2 × 105 qPCR units/L). Considering the presence of FLA, we underline the importance of a wider microbiological risk assessment in natural mineral waters despite the absence of cultivable bacteria.

Assessment of the post-mortem inspection of beef, sheep, goats and pigs in Australia: Approach and qualitative risk-based results

A risk-based assessment of post-mortem inspection activities and disposition judgment criteria was undertaken for cattle, sheep, goats and pigs in Australia against the current Australian Standard (AS 4696). The assessment utilized Codex Alimentarius Commission principles and guidelines for the conduct of microbiological risk assessment and the Code of Hygienic Practice for Meat. The assessment aimed to identify priorities for evaluating alternative procedures that deliver equivalent or better food safety outcomes to the current standard. An initial qualitative risk assessment used contemporary public health and industry data for differentiating gross abnormalities as meat safety or wholesomeness issues and to assess the likely effect of current inspection procedures on overall food safety outcomes. This article details the approach taken and reports the results of the qualitative risk assessment. The priorities identified for further validation of alternative post-mortem inspection procedures, matched against the risk managers’ primary concerns include: (1) bovine tuberculosis, Cysticercus bovis and Caseous Lymphadenitis of sheep and goats - removing post-mortem inspection procedures that are no longer necessary due to the improving animal health status of Australian animals; (2) inspection of spleens and unenucleated kidneys of sheep and goats - altering or removing procedures where new knowledge of animal or foodborne disease indicates current risk management procedures are not effective; (3) routine visual inspection of pigs, visual inspection of offal of sheep and goats - assessing the effect of inspection on microbial contamination of edible product; (4) melanoma of pigs, peri-acute pneumonia of cattle and pigs, polyarthritis of cattle and pigs - reviewing the criteria used to determine disposition judgments; and (5) pleurisy of pigs - identifying procedures that are principally related to detecting gross abnormalities that affect product wholesomeness (AS4696) rather than food safety and might, therefore, be managed within quality assurance arrangements. The outcome sought from this work will be a standard where post-mortem inspection is commensurate with risk.

Quantitative Microbiological Risk Assessment of Two Street Foods Sold in a Kenyan Town with Regard to Salmonella Contamination

Street sold foods have gained popularity in recent times, particularly in developing countries where their sale is often unregulated, hence, has a potential to transmitting pathogenic microorganisms which are of public health concern. A survey of two street foods, kachumbari (a type of a vegetable salad) and mandazi (a type of a wheat-based flour snack) was carried out in a Kenyan town to determine the prevalence and conduct a quantitative microbiological risk assessment to estimate the risks of infection due to consumption of the two products contaminated with Salmonella. A prevalence of 19% (16 out of 86 samples) and 7% (6 out of 86 samples) was observed for kachumbari and mandazi respectively. A risk assessment model composed of three different steps (nodes) comprising finished product (processed ready-to-eat), waiting (storage) period and consumption was used for the microbiological risk assessment. Models built in excel spreadsheets using @Risk software package, version 6 (Palisade USA) was used to obtain the inputs, outputs, and run the Monte Carlo simulations at 5000 iterations. The model estimated that in 95% of the cases, the consumers of kachumbari would be exposed to a maximum dose of 8.30 x 104 Salmonella cells per single serving. On the other hand, in 95% of the cases, consumers of mandazi would be exposed to a maximum dose of 4.0 x 104 Salmonella cells per single serving. The model also predicted that 64.3% and 69% of the population was at risk of developing salmonellosis upon consumption of contaminated kachumbari and mandazi respectively. The results indicate that these two products can contribute to high levels of salmonellosis morbidity. Nevertheless, a significant reduction in the level of ingested Salmonella cells in kachumbari and mandazi could be attained through a reduction of the prevalence of the pathogen contamination at or before the point of sale by the employment of good hygienic practices during their preparation and subsequent handling, in addition to enforcement of food hygiene regulations regarding street foods to ensure microbiologically safe foods are sold to the consumers. In order to improve the accuracy of this risk assessment model, more data, whenever available should be used in such studies.

Prevalence, Antibiotic Susceptibility and Diversity of Vibrio parahaemolyticus Isolates in Seafood from South China.

Vibrio parahaemolyticus is a leading cause of foodborne infections in China and a threat to human health worldwide. The main objective of this study is to determine the prevalence and characteristic of V. parahaemolyticus isolates in fish, oyster and shrimp samples from the South China domestic consumer market. To accomplish this, we examined 504 seafood samples from 11 provinces of China. The prevalence rates were 9.38, 30.36, and 25.60%, respectively. In summer (33.33%), the prevalence of V. parahaemolyticus was more common than that detected in the winter (14.01%). In addition, we identified 98 V. parahaemolyticus strains. The antimicrobial resistance trends of our seafood isolates to 15 antimicrobial agents revealed that major isolates were resistant to ampicillin (79.59%). Furthermore, 68.38% of the isolates were identified as being multidrug resistance. The prevalence of tdh or trh genes among the isolates was 8.16 and 12.24%, respectively. ERIC-PCR and multilocus sequence typing (MLST) results enabled classification of the isolates (n = 98) into different clusters, revealing genetic variation and relatedness among the isolates. Thus, our findings demonstrate the prevalence of V. parahaemolyticus in a variety of common seafood consumed domestically in China and provides insights into the dissemination of antibiotic-resistant strains, which should improve our microbiological risk assessment knowledge associated with V. parahaemolyticus in seafoods.