食源性致病菌生长延滞期的研究进展

食源性致病菌是引起食源性疾病的首要致病因子，为了定量评估由其引起的食品安全风险、评价食品加工工艺对其控制的有效性，需利用预测微生物学模型估算食源性致病菌的相关生长或失活参数。生长延滞期是描述食源性致病菌生长的重要参数，受多种因素影响，尤其是低菌量水平下细胞生长变异性使得生长延滞期更难以准确获取。本文结合近年来国内外相关研究，系统地总结了食源性致病菌生长延滞期的检测方法及影响因素，并介绍可作为生长延滞期生理标记的相关胞内活动，最后对生长延滞期研究的发展趋势提出建议，以期为今后的研究提供参考。     

Consumer food-handling behaviors associated with prevention of 13 foodborne illnesses

To be effective in reducing the incidence of foodborne illness, consumers and food safety educators need information about behaviors that will decrease exposure to foodborne pathogens. A four-round Delphi technique was used to survey nationally recognized experts in food microbiology, epidemiology, food safety education, and food safety policy with the aim of identifying and ranking food-handling and consumption behaviors associated with 13 major foodborne pathogens. The food safety experts ranked behaviors related to keeping foods at safe temperatures as of primary importance in preventing illness caused by Bacillus cereus and Clostridium perfringens and of secondary importance in preventing illness caused by Staphylococcus aureus. The use of a thermometer to cook foods adequately was ranked as of primary importance for the prevention of illness caused by Campylobacter jejuni, Salmonella species, Escherichia coli O157:H7, Toxoplasma gondii, and Yersinia enterocolitica, with the avoidance of cross-contamination being ranked as of secondary importance for most of these pathogens. Hand washing was the top-ranked behavior for the prevention of shigellosis. The avoidance of certain foods that are likely to be contaminated was the top-ranked behavior for the prevention of illnesses caused by Listeria monocytogenes, Noroviruses, and Vibrio species. The expert panel's ranking of behaviors for the reduction of the risk of illness caused by major foodborne pathogens can enable consumers to make informed choices about food consumption and handling behaviors and can guide food safety educators in prioritizing their educational efforts.     

Physicochemical aspects of the microbiology of edible table spreads

This article describes aspects of the microbiology of edible table spreads including milk fat spreads such as butter, fat spreads of the margarine type and mixed fat spreads with fat contents ranging from 80–95% to not less than 20% by weight of the product. The water-in-oil character of these products makes a major contribution to their microbiological stability especially after they have been exposed to the micro-organisms commonly encountered in a domestic environment. The microbiological stability of edible table spreads is also influenced by the concentration and physical nature of the continuous lipid phase with product stability increasing with greater proportions of crystallized fat. Edible table spreads containing higher proportions of water are more vulnerable to microbiological deterioration. This can be controlled by ensuring a dispersed aqueous phase in the product which consists of small discrete moisture droplets stabilized against coalescence. This stabilization can be achieved by the use of increased mono- and diglyceride concentrations and/or by increasing the viscosity of the dispersed moisture droplets through the use of stabilizers, thickeners and protein. The development of unacceptable levels of microbiological deterioration during domestic use is prevented by the addition of potassium sorbate to the aqueous phase. Additive free edible table spreads with acceptable shelf-life can be manufactured by controlling the distribution of dispersed moisture droplet size and nutrient composition .     

Consumer acceptance of irradiated meat and poultry in the United States.

Food manufacturers in the United States are currently allowed to irradiate raw meat and poultry to control microbial pathogens and began marketing irradiated beef products in mid-2000. Consumers can reduce their risk of foodborne illness by substituting irradiated meat and poultry for nonirradiated products, particularly if they are more susceptible to foodborne illness. The objective of this study was to identify the individual characteristics associated with willingness to buy irradiated meat and poultry, with a focus on five risk factors for foodborne illness: unsafe food handling and consumption behavior, young and old age, and compromised immune status. A logistic regression model of willingness to buy irradiated meat or poultry was estimated using data from the 1998-1999 FoodNet Population Survey, a single-stage random-digit dialing telephone survey conducted in seven sites covering 11% of the U.S. population. Nearly one-half (49.8%) of the 10,780 adult respondents were willing to buy irradiated meat or poultry. After adjusting for other factors, consumer acceptance of these products was associated with male gender, greater education, higher household income, food irradiation knowledge, household exposure to raw meat and poultry, consumption of animal flesh, and geographic location. However, there was no difference in consumer acceptance by any of the foodborne illness risk factors. It is unclear why persons at increased risk of foodborne illness were not more willing to buy irradiated products, which could reduce the hazards they faced from handling or undercooking raw meat or poultry contaminated by microbial pathogens.     

Clostridium botulinum in the post-genomic era

Foodborne botulism is a severe neuroparalytic disease caused by consumption of botulinum neurotoxin formed by strains of proteolytic Clostridium botulinum and non-proteolytic C. botulinum during their growth in food. The botulinum neurotoxin is the most potent substance known, with as little as 30-100 ng potentially fatal, and consumption of just a few milligrams of neurotoxin-containing food is likely to be sufficient to cause illness and potentially death. In order to minimise the foodborne botulism hazard, it is necessary to extend understanding of the biology of these bacteria. This process has been recently advanced by genome sequencing and subsequent analysis. In addition to neurotoxin formation, endospore formation is also critical to the success of proteolytic C. botulinum and non-proteolytic C. botulinum as foodborne pathogens. The endospores are highly resistant, and enable survival of adverse treatments such as heating. To better control the botulinum neurotoxin-forming clostridia, it is important to understand spore resistance mechanisms, and the physiological processes involved in germination and lag phase during recovery from this dormant state.     

Bacterial dormancy in Campylobacter: abstract theory or cause for concern?

For the past 100 years, since the birth of modern microbiology, this discipline has predominantly relied on the ability to culture micro-organisms in vitro on artificial synthetic culture media under controlled conditions in the laboratory. However, sometimes it is not possible to detect foodborne pathogens using such conventional techniques. Employment of these techniques can also lead to a delay in detection of pathogens. The 'viable but non-culturable' (VNC) cellular form has been demonstrated in Campylobacter jejuni , representing a resting or dormant stage, which is induced through cell stress including starvation. This form is extremely difficult to detect and generally requires complex and sophisticated technology which is usually not available in most routine food microbiology laboratories. This review aims at examining the role of this cell form in Campylobacter , including their historical evolution, formation, physiology, detection and to discuss the challenges that this form presents to food safety.     

Control of Salmonella Contamination of Shell Eggs—Preharvest and Postharvest Methods: A Review

Salmonella Enteritidis is one of the most prevalent foodborne pathogen, its main reservoir being considered the shell egg. As the concerns related to the increasing human salmonellosis cases grow, the need for an application of preventive methods either at the farm level or during the processing steps is crucial for a better control of the foodborne outbreaks due to the consumption of this specific food product. This review focuses on the application of preventive methods at the farm level, on preharvest step, in order to reduce the risk of shell eggs contamination with Salmonella, especially S. Enteritidis, through a better control of the laying hens’ infection with this pathogen. As postharvest methods, a 1st approach is the egg storage conditions and the prevention of Salmonella spp. growth and multiplication. In addition, shell eggs may be subjected to eggshell decontamination, to reduce the risk of foodborne outbreaks. Several of these latter mentioned methods are already authorized to be put in place in different countries, as it is the case in the United States of America and Canada. Their efficacy has been proven and their use is regarded by some as mandatory for ensuring shell eggs safety for the consumers.     

THE MICROBIOLOGY OF FOODBORNE DISEASE OUTBREAKS: AN UPDATE1

Illnesses or diseases transmitted by food are referred to as foodborne illnesses and are the result of consumption of foods contaminated with pathogenic bacteria and/or their toxins, viruses, parasites, chemicals or other substances hazardous to human health. The recent literature has been reviewed. Terminology, sources, economics, prevention and control of foodborne illness outbreaks in the United States in recent years are reported. Bacterial foodborne outbreaks far outweigh those caused by other sources. Three contributing factors are responsible for more than 87% of the foodborne outbreaks for the period 1980–1985. Control of implicated microorganisms can reduce outbreaks of foodborne disease and assure a safe, wholesome and nutritious food supply.     

Microbiological safety of mayonnaise, salad dressings, and sauces produced in the United States: a review

The literature on the death and survival of foodborne pathogens in commercial mayonnaise, dressing, and sauces was reviewed and statistically analyzed with emphasis on Salmonella, Escherichia coli O157:H7, and Listeria monocytogenes. The absence of reports of foodborne illness associated directly with the consumption of commercially prepared acidic dressings and sauces is evidence of their safety. Salmonella, E. coli O157:H7, E. coli, L. monocytogenes, Staphylococcus aureus, and Yersinia enterocolitica die when inoculated into mayonnaise and dressings. Historically, mayonnaise and dressings have been exempt from the acidified food regulations and have justly deserved this status due primarily to the toxic effect of acetic and to a lesser extent lactic and citric acids. These organic acids are inimical to pathogenic bacteria and are effective natural preservatives with acetic being the most effective in killing pathogenic bacteria at the pH values encountered in these products. Statistical analysis on data reported in the literature shows that the most important and significant factor in destroying pathogenic bacteria is pH as adjusted with acetic acid followed by the concentration of acetic acid in the water phase. The reported highest manufacturing target pH for dressings and sauces is 4.4, which is below the 4.75 pKa of acetic acid and below the reported inhibitory pH of 4.5 for foodborne pathogens in the presence of acetic acid. The overall conclusion is that these products are very safe. They should remain exempt from the acidified food regulations providing adequate research has been done to validate their safety, and the predominant acid is acetic and reasonable manufacturing precautions are taken.     

Food Safety Challenges within North American Free Trade Agreement (NAFTA) Partners

Abstract: Organizational elements and limitations influencing the effective operation of the food safety regulatory infrastructures in the United States, Canada, and Mexico are compared. Progress to improve the safety of food in North American countries is hampered by common problems, yet differences exist. Foodborne illness surveillance and reporting are most comprehensive in the United States, but it is uniformly more reactive than proactive in all 3 countries. Food safety policy is based on outbreak data, but that may be short‐sighted because these represent roughly 10% of foodborne illness cases. Food inspection in each country is done at 2 tiers (federal and other) by many agencies at 3 (federal/state‐provincial/municipal) levels. Interagency collaboration at times of crisis is weak and frequent heterogeneity in training, inspection targets, and inspection rigor affect regulatory credibility. Enhanced recognition that industry has the prime responsibility for food safety is warranted (and must not be confused with self‐inspection) along with justifiably aggressive regulatory agency interrogation of food safety system performance. End product testing should be used to verify safety system operation and should not be used to predict product safety. Specific microbial and nonmicrobial challenges to safe food in North America are highlighted and a rationalization of fiscal/human resource allocation to most effectively reduce the burden of foodborne illness is provided.     

Foodborne disease in the United States, 1946–1986

Not all gastrointestinal illnesses are foodborne, and not all foodborne diseases cause symptoms in the digestive tract. More foodborne disease outbreaks and many more individual foodborne illnesses are being reported in the US every year, but there are reasons to suppose that underreporting by a factor of 10 or more continues, even though reporting in the US may be the most complete and timely of systems in developed countries. Although a great many more causes of foodborne disease have been recognized during the past 40 years, it does not appear that the proportion of outbreaks or cases of foodborne illness for which etiology can be established has increased during this period. The vast majority of reported foodborne illnesses (infections and intoxications) are of microbial etiology. Allergies and intolerances, which are known to be foodborne but affect fewer people, and cancer, heart disease, and behavioral disorders, which are alleged to be at least partially foodborne, have also to be considered in connection with the safety of food supplies in the US and elsewhere.     

大型国际综合性运动会运动员村食品卫生管理模式的研究

为给北京 2 0 0 8年奥运会食品卫生管理提供科学依据 ,应用危险性分析和HACCP原则对2 0 0 1年北京大运会大运村食品卫生进行管理 ,食品合格率达到较高水平 ,实现了杜绝食物中毒的既定目标 ,提示危险性分析和HACCP原则可在大型国际综合性运动会运动员村食品卫生管理中发挥有效作用。     

Using expert elicitation to link foodborne illnesses in the United States to foods

U.S. foodborne illness risk analysis would benefit greatly from better information on the relationship between the incidence of foodborne illness and exposure to foodborne pathogens. In this study, expert elicitation was used to attribute U.S. foodborne illnesses caused by the nine FoodNet pathogens, Toxoplasma gondii, and noroviruses to consumption of foods in 11 broad categories. Forty-two nationally recognized food safety experts responded to a formal written expert elicitation survey. For each pathogen, respondents gave their best estimate of the distribution of foodborne illnesses associated with each of the food categories and the 90% confidence bounds on each of their estimates. Based on the work of Paul Mead and his coauthors, food attribution percentage estimates from this study were used to attribute case, hospitalization, and death incidence estimates to foods according to pathogen. These attribution estimates indicate that 15 food-pathogen pairs account for 90% of the illnesses, 25 pairs account for 90% of hospitalizations, and 21 pairs account for 90% of deaths.     

Microgreen nutrition,food safety,and shelf life: A review

Microgreens have gained increasing popularity as food ingredients in recent years because of their high nutritional value and diverse sensorial characteristics. Microgreens are edible seedlings including vegetables and herbs, which have been used, primarily in the restaurant industry, to embellish cuisine since 1996. The rapidly growing microgreen industry faces many challenges. Microgreens share many characteristics with sprouts, and while they have not been associated with any foodborne illness outbreaks, they have recently been the subject of seven recalls. Thus, the potential to carry foodborne pathogens is there, and steps can and should be taken during production to reduce the likelihood of such incidents. One major limitation to the growth of the microgreen industry is the rapid quality deterioration that occurs soon after harvest, which keeps prices high and restricts commerce to local sales. Once harvested, microgreens easily dehydrate, wilt, decay and rapidly lose certain nutrients. Research has explored preharvest and postharvest interventions, such as calcium treatments, modified atmopsphere packaging, temperature control, and light, to maintain quality, augment nutritional value, and extend shelf life. However, more work is needed to optimize both production and storage conditions to improve the safety, quality, and shelf life of microgreens, thereby expanding potential markets.     

Emerging foodborne pathogens

The broad spectrum of foodborne infections has changed dramatically over time, as well-established pathogens have been controlled or eliminated, and new ones have emerged. The burden of foodborne disease remains substantial: one in four Americans is estimated to have a significant foodborne illness each year. The majority of these illnesses are not accounted for by known pathogens, so more must remain to be discovered. Among the known foodborne pathogens, those more recently identified predominate, suggesting that as more and more is learned about pathogens, they come under control. In addition to the emergence or recognition of new pathogens, other trends include global pandemics of some foodborne pathogens, the emergence of antimicrobial resistance, the identification of pathogens that are highly opportunistic, affecting only the most high-risk subpopulations, and the increasing identification of large and dispersed outbreaks. New pathogens can emerge because of changing ecology or changing technology that connects a potential pathogen with the food chain. They also can emerge de novo by transfer of mobile virulence factors, often through bacteriophage. Though this is rarely observed, it can be reconstructed. Better understanding of the ecology and dynamics of phage transmission among bacteria will help us to understand the appearance of new pathogens in the future. One may look for emerging foodborne pathogens among the silent zoonoses, and among the severe infections affecting the immunocompromised humans. We should expect the unexpected. In the past, separating human sewage and animal manure from human food and water supplies was critical to improving public health. Now, our health depends increasingly on the safety of the feed and water supplies for the animals themselves. The successes of the 20th century and the new challenges we face mean that public health vigilance, careful investigation of new problems, responsible attention to food safety from farm to table, and partnerships to bring about new foodborne disease control measures will be needed for the foreseeable future.     

Popular Ethnic Foods in the United States: A Historical and Safety Perspective

In recent years, a dramatic increase in the demand for ethnic foods in the United States has been observed. Interestingly, with their rise in popularity, more foodborne illness outbreaks associated with ethnic foods have also been reported. Despite a more than 200‐y history of ethnic foods in the United States, there is a paucity of information about them. Furthermore, there is also a lack of research on food safety issues involving ethnic foods. Therefore, this paper provides a comprehensive overview of ethnic foods, including the history, types, popularity, characteristics, ingredients, and consumer attitudes toward them. Importantly, this review provides an analysis of the statistics of foodborne illness outbreaks associated with ethnic foods based on data from the Centers for Disease Control and Prevention (CDC). The breakdown of etiology of ethnic foods identified the number of total outbreaks, the causative microorganisms, the food vectors, and the locations where foodborne disease outbreaks have occurred. Also covered is a review of the Hazard Analysis Critical Control Point (HACCP) system implementation, food safety training, and inspection score systems related to ethnic foods and how these can serve as effective tools for the prevention of foodborne illness outbreaks. This study contributes to the body of food safety literature by providing helpful information about ethnic foods in the United States.     

INCIDENCE AND DIARRHEGENIC POTENTIAL OF BACILLUS CEREUS IN PASTEURIZED MILK AND CEREAL PRODUCTS IN THAILAND

ABSTRACT

Bacillus cereus, bacteria that commonly occur in foods, can potentially cause foodborne illness. Two important factors that contribute to the illness are the number of B. cereus in food and the ability of the organism to produce enterotoxins. This study investigated the number of B. cereus cells in dairy and cereal products in Thailand, using the plate count method and the presence of diarrheal‐enterotoxin genes in the isolates through the polymerase chain reaction (PCR). The genes encoding hemolysin BL (hblA, hblC, hblD), nonhemolytic enterotoxin (nheA, nheB, nheC), cytotoxin K (cytK) and enterotoxin FM (entFM) were the targets of the PCR. B. cereus was found in all pasteurized milk samples and in 37.7% of the cereal product samples, ranging from 50 to 1.7 × 10³ cfu/g. PCR results revealed that each gene occurred in more than half of the foodborne isolates tested. A large proportion (96%) of the isolates harbored enterotoxin genes and is considered to be potentially diarrhegenic.

PRACTICAL APPLICATIONS

Significant frequency of Bacillus cereus contamination in pasteurized milk and cereal products, and the large proportion of diarrhegenic strains among foodborne B. cereus indicate the high risk of foodborne illness that could be caused by consumption of these foods in Thailand. This suggests that B. cereus should not be disregarded in its significance in disease control and prevention programs. Also, as complete elimination of this organism from pasteurized milk and most of the cereal products through the processing steps is not possible, proper handling and storage of these foods should be strictly applied by the food industry. This is necessary in order to prevent the growth of the organism to levels that can cause foodborne illness. This research is also relevant to other developing countries having similar situations as Thailand, where data concerning the number of B. cereus in foods, frequency of contamination and proportion of enterotoxigenic B. cereus are limited, and where B. cereus gastroenteritis could be underestimated.     

国内外急性胃肠炎和食源性疾病负担研究进展

食源性疾病是全球重要的公共卫生问题,也是中国最大的食品安全问题.急性胃肠炎人群负担的评估是食源性疾病负担评估的一个中心问题,许多国家已开展急性胃肠炎和食源性疾病负担评估研究,我国于2010-2011年在部分省份开展了研究疾病负担的试点工作.本文对急性胃肠炎和食源性疾病负担评估国内外研究进展进行综述.     

Salmonella and broiler processing in the United States: Relationship to foodborne salmonellosis

Salmonella is one of the leading causes of foodborne illness worldwide, with over 40,000 cases reported each year in the United States alone. Salmonella is often associated with foods of animal origin, with chicken and dishes containing chicken often thought to be the most likely source. The Food Safety Inspection Service of the United States Department of Agriculture keeps data on the serotypes of Salmonella isolated from Hazard Analysis Critical Control Point verification samples obtained each year. The Centers for Disease Control and Prevention (CDC) publishes the most common Salmonella serotypes isolated from human disease each year. In addition, CDC maintains records of all reported foodborne outbreaks and the vehicle of illness, when determined. This review examines the overall prevalence of Salmonella serotypes isolated from broilers, the serotypes most commonly associated with human illness, and serotypes most commonly found in foodborne salmonellosis associated with chicken or chicken containing products.