Antimicrobial resistance among gram-negative foodborne bacterial pathogens associated with foods of animal origin

Antimicrobial-resistant foodborne pathogens are acquired primarily through consumption of contaminated food of animal origin or water. While there is much disagreement on the health burden imposed by resistance in foodborne bacterial pathogens, it is generally agreed that the use of antimicrobials, whether for growth promotion, prevention, or treatment, can select for resistant bacterial pathogens, and that these pathogens can be transmitted on food originating from sites processing treated animals. Information on the evolution and dissemination of antimicrobial resistance in foodborne pathogens shows that the situation is complex and differs by organism and antimicrobial. A clearer understanding of the ecology of resistance is needed in order to support science-based assessments of the public health risks due to the use of antimicrobials in the animal husbandry environment.     

Subtyping of Bacterial Foodborne Pathogens

Phenotype-based and DNA-based subtyping methods allow for differentiation of bacterial isolates beyond the species and subspecies level. Bacterial subtyping methods not only have improved our ability to detect and track foodborne disease outbreaks, but also represent tools to track sources of bacterial contamination throughout the food system. The use of subtyping methods furthermore provides an opportunity to better understand the population genetics, epidemiology, and ecology of different foodborne pathogens. The last 5 years have seen tremendous advancement in the development of sensitive, rapid, automated, and increasingly easy-to-use molecular subtyping methods for a variety of different bacterial foodborne pathogens. This review will highlight key aspects of different subtyping methods for bacterial foodborne pathogens and provide examples of their applications in public health, food safety, epidemiology, and population genetics. Molecular subtyping and characterization methods may also facilitate the development of a novel framework for tracking, preventing, and regulating foodborne bacterial diseases, which is based on evolutionary relationships and genetic characteristics rather than traditional species definitions.     

Emerging foodborne diseases.

The epidemiology of foodborne diseases is rapidly changing. Recently described pathogens, such as Escherichia coli O157:H7 and the epidemic strain of Salmonella serotype Typhimurium Definitive Type 104 (which is resistant to at least five antimicrobial drugs), have become important public health problems. Well-recognized pathogens, such as Salmonella serotype Enteritidis, have increased in prevalence or become associated with new vehicles. Emergence in foodborne diseases is driven by the same forces as emergence in other infectious diseases: changes in demographic characteristics, human behavior, industry, and technology; the shift toward a global economy; microbial adaptation; and the breakdown in the public health infrastructure. Addressing emerging foodborne diseases will require more sensitive and rapid surveillance, enhanced methods of laboratory identification and subtyping, and effective prevention and control.     

PulseNet: the molecular subtyping network for foodborne bacterial disease surveillance, United States

PulseNet, the national molecular subtyping network for foodborne disease surveillance, was established by the Centers for Disease Control and Prevention and several state health department laboratories to facilitate subtyping bacterial foodborne pathogens for epidemiologic purposes. PulseNet, which began in 1996 with 10 laboratories typing a single pathogen (Escherichia coli O157:H7), now includes 46 state and 2 local public health laboratories and the food safety laboratories of the U.S. Food and Drug Administration and the U.S. Department of Agriculture. Four foodborne pathogens (E. coli O157:H7; nontyphoidal Salmonella serotypes, Listeria monocytogenes and Shigella) are being subtyped, and other bacterial, viral, and parasitic organisms will be added soon.     

Intensive swine production and pork safety

Major structural changes in livestock production in developed countries, particularly intensive confinement production and increases in herd and flock sizes, have raised several societal concerns about the future directions and implications of livestock food production, including the safety of meat products. This review of the major parasitic and bacterial foodborne pathogens associated with pork production indicates that pork safety in the United States has improved demonstrably over recent decades. Most notably, changes in swine production methods have been associated with virtual elimination of risk of the foodborne parasites Taenia solium, Trichinella spiralis, and Toxoplasma gondii from pigs reared on modern intensive farms. This represents a substantial public health achievement that has gone largely unheralded. Regulatory changes have led to demonstrably lower prevalence of Salmonella on pork carcasses, but control of bacterial foodborne pathogens on farms remains a significant challenge. Available evidence does not support the hypothesis that intensive pork production has increased risk for the major bacterial foodborne pathogens that are common commensals of the pig (Salmonella, Campylobacter, Listeria, and Yersinia enterocolitica), or that pigs produced in alternative systems are at reduced risk of colonization with these organisms. However, pigs raised in outdoor systems inherently confront higher risks of exposure to foodborne parasites, particularly T. gondii.     

Foodborne pathogens in milk and the dairy farm environment: food safety and public health implications

Milk and products derived from milk of dairy cows can harbor a variety of microorganisms and can be important sources of foodborne pathogens. The presence of foodborne pathogens in milk is due to direct contact with contaminated sources in the dairy farm environment and to excretion from the udder of an infected animal. Most milk is pasteurized, so why should the dairy industry be concerned about the microbial quality of bulk tank milk? There are several valid reasons, including (1) outbreaks of disease in humans have been traced to the consumption of unpasteurized milk and have also been traced back to pasteurized milk, (2) unpasteurized milk is consumed directly by dairy producers, farm employees, and their families, neighbors, and raw milk advocates, (3) unpasteurized milk is consumed directly by a large segment of the population via consumption of several types of cheeses manufactured from unpasteurized milk, (4) entry of foodborne pathogens via contaminated raw milk into dairy food processing plants can lead to persistence of these pathogens in biofilms, and subsequent contamination of processed milk products and exposure of consumers to pathogenic bacteria, (5) pasteurization may not destroy all foodborne pathogens in milk, and (6) inadequate or faulty pasteurization will not destroy all foodborne pathogens. Furthermore, pathogens such as Listeria monocytogenes can survive and thrive in post-pasteurization processing environments, thus leading to recontamination of dairy products. These pathways pose a risk to the consumer from direct exposure to foodborne pathogens present in unpasteurized dairy products as well as dairy products that become re-contaminated after pasteurization. The purpose of this communication is to review literature published on the prevalence of bacterial foodborne pathogens in milk and in the dairy environment, and to discuss public health and food safety issues associated with foodborne pathogens found in the dairy environment. Information presented supports the model in which the presence of pathogens depends on ingestion of contaminated feed followed by amplification in bovine hosts and fecal dissemination in the farm environment. The final outcome of this cycle is a constantly maintained reservoir of foodborne pathogens that can reach humans by direct contact, ingestion of raw contaminated milk or cheese, or contamination during the processing of milk products. Isolation of bacterial pathogens with similar biotypes from dairy farms and from outbreaks of human disease substantiates this hypothesis.     

Food safety in the 21st century.

The global importance of food safety is not fully appreciated by many public health authorities despite a constant increase in the prevalence of foodborne illness. Numerous devastating outbreaks of salmonellosis, cholera, enterohaemorrhagic Escherichia coli infections, hepatitis A and other diseases have occurred in both industrialized and developing countries. In addition, many of the re-emerging or newly recognized pathogens are foodborne or have the potential of being transmitted by food and/or drinking water. More foodborne pathogens can be expected because of changing production methods, processes, practices and habits. During the early 21st century, foodborne diseases can be expected to increase, especially in developing countries, in part because of environmental and demographic changes. These vary from climatic changes, changes in microbial and other ecological systems, to decreasing freshwater supplies. However, an even greater challenge to food safety will come from changes resulting directly in degradation of sanitation and the immediate human environment. These include the increased age of human populations, unplanned urbanization and migration and mass production of food due to population growth and changed food habits. Mass tourism and the huge international trade in food and feed is causing food and feedborne pathogens to spread transnationally. As new toxic agents are identified and new toxic effects recognized, the health and trade consequences of toxic chemicals in food will also have global implications. Meeting the huge challenge of food safety in the 21st century will require the application of new methods to identify, monitor and assess foodborne hazards. Both traditional and new technologies for assuring food safety should be improved and fully exploited. This needs to be done through legislative measures where suitable, but with much greater reliance on voluntary compliance and education of consumers and professional food handlers. This will be an important task for the primary health care system aiming at "health for all".     

2007-2014年细菌性食源性疾病病原菌检测结果分析

摘要:目的　分析厦门市思明区多年来细菌性食源性疾病病原菌种类、尤其是流行特征及实验室检测情况,为预防和控制食源性疾病提供科学依据。方法　对思明区2007-2014年细菌性食源性疾病实验室检测样品信息及结果进行统计分析。结果　8年共接到114起疑似细菌性食源性疾病送检样本,检测各类样本共857份,其中71起检出目标病原菌。依次以副溶血性弧菌（38.6%）、金黄色葡萄球菌（10.5%）、蜡样芽胞杆菌（5.3%）、致泻性大肠埃希菌（2.6%）和沙门菌（2.6%）为主要致病菌,第三季度发生率最高为49.1%（56/114）。结论　思明区细菌性食源性疾病以副溶血性弧菌为主要病原菌,且O3血清型为主;夏秋为高发季节。诺如病毒是非细菌性食源性感染的主要病毒。掌握食源性疾病的发生规律,加强食品卫生安全监督管理,制定针对性的预防措施,可有效预防和控制食源性疾病的发生。     

细菌性食源性疾病实验诊断及关键控制点分析研究

目的：对扬州市近10年70起细菌性食源性疾病实验诊断结果进行分析，进行危害分析(HA)并寻找细菌性食源性疾病的关键控制点(CCPs)。方法：对引起70起细菌性食源性疾病病原菌、病原菌的来源、主要污染食物、发生季节进行分析。结果：由致病性弧菌引起食源性疾病占58．57％。厨师带菌引起食源性疾病占54．28％。熟食间检出的致病菌株占食品株的91．30％。7～9月份发生的食源性疾病占65．72％。结论：细菌性食源性疾病主要危害因素是致病性弧菌、沙门菌、金黄色葡萄球菌。冷盘(菜)是引起食源性疾病的主要食物。熟食间卫生管理、从业人员的健康体检及卫生素质培训、防止交叉污染、夏秋季节防止细菌繁殖是控制食源性疾病的关键控制点。     

Standardization of pulsed-field gel electrophoresis protocols for the subtyping of Escherichia coli O157:H7, Salmonella, and Shigella for PulseNet

Standardized rapid pulsed-field gel electrophoresis (PFGE) protocols for the subtyping of Escherichia coli O157:H7, Salmonella serotypes, and Shigella species are described. These protocols are used by laboratories in PulseNet, a network of state and local health departments, and other public health laboratories that perform real-time PFGE subtyping of these bacterial foodborne pathogens for surveillance and outbreak investigations. Development and standardization of these protocols consisted of a thorough optimization of reagents and reaction conditions to ensure that the protocols yielded consistent results and high-quality PFGE pattern data in all the PulseNet participating laboratories. These rapid PFGE protocols are based on the original 3-4-day standardized procedure developed at Centers for Disease Control and Prevention that was validated in 1996 and 1997 by eight independent laboratories. By using these rapid standardized PFGE protocols, PulseNet laboratories are able to subtype foodborne pathogens in approximately 24 h, allowing for the early detection of foodborne disease case clusters and often aiding in the identification of the source responsible for the infections.     

Preliminary FoodNet data on the incidence of foodborne illnesses--selected sites,United States, 2002

In the United States, an estimated 76 million persons contract foodborne illnesses each year. CDC's Emerging Infections Program Foodborne Diseases Active Surveillance Network (FoodNet) collects data on 10 foodborne diseases in nine U.S. sites. FoodNet follows trends in foodborne infections by using laboratory-based surveillance for culture-confirmed illness caused by several enteric pathogens commonly transmitted through food. This report describes preliminary surveillance data for 2002 and compares them with 1996-2001 data. The data indicate a sustained decrease in major bacterial foodborne illnesses such as Campylobacter and Listeria, indicating progress toward meeting the national health objectives of reducing the incidence of foodborne infections by 2010 (objectives 10-1a to 10-1d). However, the data do not indicate a sustained decline in other major foodborne infections such as Escherichia coli O157 and Salmonella, indicating that increased efforts are needed to reduce further the incidence of foodborne illnesses.     

南京市主要细菌性病原体食源性疾病负担研究

目的 研究南京市主要细菌性病原体致食源性疾病负担,提出食源性疾病监测策略。方法 根据南京市11个区17家食源性疾病哨点医院主动监测和食源性疾病负担调查结果,结合各主要细菌性病原体的食源性比例等各项乘数,获得人群中各主要细菌性病原体的发病率及疾病负担。结果 2015年全市共采集1 208份食源性疑似病例生物标本,检出非伤寒沙门氏菌31株、副溶血性弧菌20株、致泻大肠埃希氏菌15株,检出率分别为2.57%、1.66%、2.56%;全市疾病负担调查3 600人,急性胃肠炎的月患病率为3.9%,年发病率为0.55次/人年;推算出南京市非伤寒沙门氏菌食源性感染发病率为1 292/10万,0~4岁年龄组发病率最高(3 481/10万);副溶血性弧菌食源性感染发病率为619/10万,15~24岁年龄组发病率最高(2 076/10万),致泻性大肠埃希氏菌的食源性感染发病率为1 653/10万,5~14岁年龄组发病率最高(5 263/10万)。结论 南京市非伤寒沙门氏菌、副溶血性弧菌、致泻性大肠埃希氏菌感染负担较重,儿童非伤寒沙门氏菌和致泻性大肠埃希氏菌、青壮年副溶血性弧菌的感染负担尤为突出,针对不同人群加强相应病原体的监测,同时应进一步完善相关监测及研究,为制定相应的风险控制措施提供科学依据。     

From Farm to Table to Brain: Foodborne Pathogen Infection and the Potential Role of the Neuro-immune-endocrine System in Neurotoxic Sequelae

The American diet is among the safest in the world; however, diseases transmitted by foodborne pathogens (FBPs) still pose a public health hazard. FBPs are the second most frequent cause of all infectious illnesses in the United States. Numerous anecdotal and clinical reports have demonstrated that central nervous system inflammation, infection, and adverse neurological effects occur as complications of foodborne gastroenteritis. Only a few well-controlled clinical or experimental studies, however, have investigated the neuropathogenesis. The full nature and extent of neurological involvement in foodborne illness is therefore unclear. To our knowledge, this review and commentary is the first effort to comprehensively discuss the issue of FBP induced neurotoxicity. We suggest that much of this information supports the role of a theoretical model, the neuro-immune-endocrine system, in organizing and helping to explain the complex pathogenesis of FBP neurotoxicity.     

Risk factors for antibiotic resistance in <Emphasis Type="Italic">Campylobacter</Emphasis> spp. isolated from raw poultry meat in Switzerland

Background  

The world-wide increase of foodborne infections with antibiotic resistant pathogens is of growing concern and is designated by the World Health Organization as an emerging public health problem. Thermophilic Campylobacter have been recognised as a major cause of foodborne bacterial gastrointestinal human infections in Switzerland and in many other countries throughout the world. Poultry meat is the most common source for foodborne cases caused by Campylobacter. Because all classes of antibiotics recommended for treatment of human campylobacteriosis are also used in veterinary medicine, in view of food safety, the resistance status of Campylobacter isolated from poultry meat is of special interest.     

From farm to table to brain: foodborne pathogen infection and the potential role of the neuro-immune-endocrine system in neurotoxic sequelae

The American diet is among the safest in the world; however, diseases transmitted by foodborne pathogens (FBPs) still pose a public health hazard. FBPs are the second most frequent cause of all infectious illnesses in the United States. Numerous anecdotal and clinical reports have demonstrated that central nervous system inflammation, infection, and adverse neurological effects occur as complications of foodborne gastroenteritis. Only a few well-controlled clinical or experimental studies, however, have investigated the neuropathogenesis. The full nature and extent of neurological involvement in foodborne illness is therefore unclear. To our knowledge, this review and commentary is the first effort to comprehensively discuss the issue of FBP induced neurotoxicity. We suggest that much of this information supports the role of a theoretical model, the neuro-immune-endocrine system, in organizing and helping to explain the complex pathogenesis of FBP neurotoxicity.     

Antimicrobial susceptibility of foodborne pathogens in organic or natural production systems: an overview

Organic and natural food production systems are increasing in popularity, at least partially because consumers perceive that these niche markets provide healthier and safer food products. One major difference between these niche markets and conventional production systems is the use of antimicrobials. Because antimicrobial agents exert selective pressures for antimicrobial resistance, relating antimicrobial susceptibility of foodborne bacteria to niche market production systems is of interest. Other differences between production systems might also influence the susceptibility of foodborne pathogens. The objective of this review is to compare the impact of food animal production systems on the antimicrobial susceptibility of common foodborne bacterial pathogens. Studies comparing the susceptibility of such pathogens were diverse in terms of geographic location, procedures, species of bacteria, and antimicrobials evaluated; thus, it was difficult to draw conclusions. The literature is highly variable in terms of production type and practices and susceptibility associations, although few studies have compared truly organic and conventional practices. When statistical associations were found between production type and minimum inhibitory concentrations or percentage of isolates resistant for a particular pathogen, the isolates from conventionally reared animals/products were more commonly resistant than the comparison group (organic, antibiotic free, etc.). Therefore, further studies are needed to better assess public health consequences of antimicrobial resistance and food animal production systems, specifically organic or natural versus conventional.     

2011年株洲市食源性致病菌监测分析

目的了解株洲市售食品中食源性致病菌污染状况及分布。方法在全国食源性疾病监测网控制体系下,2011年1～9月采集了株洲市5个监测点内的九大类食品共计159份,对这些样品进行了菌落总数、大肠菌群、霉菌、沙门菌、大肠杆菌O157:H7、单核细胞增生李斯特菌、金黄色葡萄球菌、志贺菌、阪崎菌9种食源性致病菌的监测分析。结果 159份食品样中,分离出目的菌21株,其中金黄色葡萄球菌11株,蜡样芽胞杆菌8株,沙门菌1株,单核细胞增生李斯特菌1株,总检出率13.20%。结论通过对株洲市售食品中食源性致病菌主动监测,掌握食源性致病菌的污染及流行情况,及时发现食品安全隐患,确保有效预防食源性疾病的发生     

Molecular typing methodologies for microbial source tracking and epidemiological investigations of Gram-negative bacterial foodborne pathogens

Gram-negative bacterial foodborne pathogens are a worldwide cause of morbidity and mortality. The ability to carry out epidemiological investigations to determine the primary sources of bacterial contamination is important to improve public health. Multiple methods are available for bacterial source tracking and to determine the distribution of pathogens isolated from sick patients. The molecular based typing methods available fall into three general categories: those based on restriction analysis of the bacterial DNA; those based on polymerase chain reaction (PCR) amplification of particular genetic targets; and those based on the identification of DNA sequence polymorphisms. The techniques that are examined in this review include: plasmid analysis, restriction fragment length polymorphism methods, pulsed-field gel electrophoresis, amplified fragment length polymorphism analysis, PCR-based genotyping, variable number of tandem repeat analysis, multilocus sequence typing, and single nucleotide polymorphism analysis. These methods are described along with a discussion of the strengths and weaknesses of the techniques for genotyping the major Gram-negative foodborne pathogens—Campylobacter spp., Salmonella enterica, Shigella spp., Escherichia coli, and Yersinia enterocolitica.     

Food-related illness and death in the United States.

To better quantify the impact of foodborne diseases on health in the United States, we compiled and analyzed information from multiple surveillance systems and other sources. We estimate that foodborne diseases cause approximately 76 million illnesses, 325,000 hospitalizations, and 5,000 deaths in the United States each year. Known pathogens account for an estimated 14 million illnesses, 60, 000 hospitalizations, and 1,800 deaths. Three pathogens, Salmonella, Listeria, and Toxoplasma, are responsible for 1,500 deaths each year, more than 75% of those caused by known pathogens, while unknown agents account for the remaining 62 million illnesses, 265,000 hospitalizations, and 3,200 deaths. Overall, foodborne diseases appear to cause more illnesses but fewer deaths than previously estimated.     

Perceived etiology of foodborne illness among public health personnel.

Few data exist about perceptions regarding the etiology of foodborne illness. Among public health staff throughout Tennessee, the three pathogens most commonly believed to cause foodborne illness in the United States actually account for only 12% of disease. Fewer than 3% of respondents correctly identified the leading cause of foodborne illness.