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Physiologic and molecular markers for detection of shiga toxin-producing Escherichia coli serotype O26 strains.

Knowledge of physiologic/phenotypic and genetic variation of Escherichia coli O157 and its tight clonality was the basis for development of successful detection protocols for Shiga toxin-producing E. coli (STEC) O157:H7/H. Phenotypic and genetic characteristics of diarrheagenic E. coli O26 isolates from different geographical regions may differ as indicated by representative reports from all continents. In this review, we summarize current knowledge on STEC O26, a pathogen whose emergence predates that of other STEC, including O157:H7/H-. The overall objectives are to integrate information available from peer-reviewed literature on the clinical and public health significance of STEC O26 worldwide, and to highlight phenotypic and genetic markers that could be used for routine detection of this pathogen. Our ultimate goal is to render information that will allow quick, accurate, and specific detection of STEC O26 genotypic variants worldwide, so as to aid with control of this pathogen. The information herein will be invaluable to a variety of scientists that include epidemiologists and microbiologists (medical, veterinary, food, and environmental) with interest in STEC O26--a zoonotic and emerging foodborne pathogen.

Animals↗

Chronic sequelae of foodborne disease.

In the past decade the complexity of foodborne pathogens, as well as their adaptability and ability to cause acute illness, and in some cases chronic (secondary) complications, have been newly appreciated. This overview examines long-term consequences of foodborne infections and intoxications to emphasize the need for more research and education.

Chronic Disease↗

Foodborne disease in the new millennium: out of the frying pan and into the fire?

About four million cases of foodborne infectious disease occur annually in Australia; new foodborne pathogens, such as enterohaemorrhagic Escherichia coli, are emerging. Climate change, combined with changes in how we produce and distribute food and how we behave as consumers, have the potential to affect foodborne disease in the coming century. Foodborne disease outbreaks are now more far-reaching (and sometimes global) due to modern mass food production and widespread food distribution. There are strong seasonal patterns for Salmonella and Campylobacter infection in Australia. Global warming may increase the incidence of infections, such as salmonellosis, and diseases caused by toxins, such as ciguatera.

Australia↗

Large-scale genome analysis of bovine commensal Escherichia coli reveals that bovine-adapted E. coli lineages are serving as evolutionary sources of the emergence of human intestinal pathogenic strains.

How pathogens evolve their virulence to humans in nature is a scientific issue of great medical and biological importance. Shiga toxin (Stx)-producing Escherichia coli (STEC) and enteropathogenic E. coli (EPEC) are the major foodborne pathogens that can cause hemolytic uremic syndrome and infantile diarrhea, respectively. The locus of enterocyte effacement (LEE)-encoded type 3 secretion system (T3SS) is the major virulence determinant of EPEC and is also possessed by major STEC lineages. Cattle are thought to be the primary reservoir of STEC and EPEC. However, genome sequences of bovine commensal E. coli are limited, and the emerging process of STEC and EPEC is largely unknown. Here, we performed a large-scale genomic comparison of bovine commensal E. coli with human commensal and clinical strains, including EPEC and STEC, at a global level. The analyses identified two distinct lineages, in which bovine and human commensal strains are enriched, respectively, and revealed that STEC and EPEC strains have emerged in multiple sublineages of the bovine-associated lineage. In addition to the bovine-associated lineage-specific genes, including fimbriae, capsule, and nutrition utilization genes, specific virulence gene communities have been accumulated in stx- and LEE-positive strains, respectively, with notable overlaps of community members. Functional associations of these genes probably confer benefits to these E. coli strains in inhabiting and/or adapting to the bovine intestinal environment and drive their evolution to highly virulent human pathogens under the bovine-adapted genetic background. Our data highlight the importance of large-scale genome sequencing of animal strains in the studies of zoonotic pathogens.

Animals↗

Inactivation of Escherichia coli O157:H7 and Listeria monocytogenes on plastic kitchen cutting boards by electrolyzed oxidizing water.

One milliliter of culture containing a five-strain mixture of Escherichia coli O157:H7 (approximately 10(10) CFU) was inoculated on a 100-cm2 area marked on unscarred cutting boards. Following inoculation, the boards were air-dried under a laminar flow hood for 1 h, immersed in 2 liters of electrolyzed oxidizing water or sterile deionized water at 23 degrees C or 35 degrees C for 10 or 20 min; 45 degrees C for 5 or 10 min; or 55 degrees C for 5 min. After each temperature-time combination, the surviving population of the pathogen on cutting boards and in soaking water was determined. Soaking of inoculated cutting boards in electrolyzed oxidizing water reduced E. coli O157:H7 populations by > or = 5.0 log CFU/100 cm2 on cutting boards. However, immersion of cutting boards in deionized water decreased the pathogen count only by 1.0 to 1.5 log CFU/100 cm2. Treatment of cutting boards inoculated with Listeria monocytogenes in electrolyzed oxidizing water at selected temperature-time combinations (23 degrees C for 20 min, 35 degrees C for 10 min, and 45 degrees C for 10 min) substantially reduced the populations of L. monocytogenes in comparison to the counts recovered from the boards immersed in deionized water. E. coli O157:H7 and L. monocytogenes were not detected in electrolyzed oxidizing water after soaking treatment, whereas the pathogens survived in the deionized water used for soaking the cutting boards. This study revealed that immersion of kitchen cutting boards in electrolyzed oxidizing water could be used as an effective method for inactivating foodborne pathogens on smooth, plastic cutting boards.

Colony Count, Microbial↗

A review of recent taxonomic changes in seven genera of bacteria commonly found in foods.

The purpose of this review is to call attention to the new approaches now in use that classify bacteria primarily on the basis of phylogenetic criteria. The primary laboratory methods for ascertaining phylogenetic relationships entail the use of 16S rRNA and DNA sequence comparisons. These methods have been applied to some long-established genera of bacteria of importance in foods, and seven genera (Bacillus, Clostridium, Flavobacterium, Micrococcus, Pseudomonas, Staphylococcus, and Xanthomonas) are summarized in this review. Some 121 species and strains from these seven genera were recently transferred to 36 newly created genera. The new genera consist of general environmental contaminants and some food spoilage species. To date, significant taxonomic changes have not been reported for foodborne pathogens. These taxonomic shifts need to be examined with respect to the utility of widely used microscopic, cultural, and serologic methods for future use in food microbiology. Phylogeny-based detection and identification methods for foodborne bacteria must be further developed for larger numbers of foodborne genera in order to keep up with the current trends in taxonomy.

Bacteria↗

Biological control of postharvest decays of apple can prevent growth of Escherichia coli O157:H7 in apple wounds.

Fresh cells of the antagonist Pseudomonas syringae at 2.4 x 10(8) CFU/ml inoculated into wounds of 'Golden Delicious' apple prevented Escherichia coli O157:H7 (concentrations ranging from 2.4 x 10(5) to 2.4 x 10(7) CFU/ml) from growing in the wounds. This occurred when the two microorganisms were co-inoculated or inoculation with E. coli O157:H7 was conducted 1 or 2 days after inoculation with the antagonist. In similar tests, application of the commercial formulation of this antagonist prevented the growth of E. coli O157:H7 in wounds when inoculated 1 or 2 days after application of the antagonist. Populations of E. coli O157:H7 in wounds treated with water (control) before inoculation with this pathogen increased approximately 2 log units during the first 48 h after inoculation. These results indicate that biocontrol agents developed for controlling storage decays of fruits may have the additional benefit of preventing the growth of foodborne pathogens in freshly wounded tissue of intact and fresh-cut fruits.

Antibiosis↗

Fate of Listeria monocytogenes, Salmonella typhimurium DT104, and Escherichia coli O157:H7 in Labneh as a pre- and postfermentation contaminant.

Commercially pasteurized milk (approximately 2% milkfat) was heated at 85 to 87 degrees C/30 min, inoculated to contain 2,000 to 6,000 CFU/ml of Listeria monocytogenes, Salmonella typhimurium DT104, or Escherichia coli O157:H7, cultured at 43 degrees C for 4 h with a 2.0% (wt/wt) commercial yogurt starter culture, stored 12 to 14 h at 6 degrees C, and centrifuged to obtain a Labneh-like product. Alternatively, traditional salted and unsalted Labneh was prepared using a 3.0% (wt/wt) starter culture inoculum, similarly inoculated after manufacture with the aforementioned pathogens, and stored at 6 degrees C and 20 degrees C. Throughout fermentation, Listeria populations remained unchanged, whereas numbers of Salmonella increased 0.33 to 0.47 logs during the first 2 h of fermentation and decreased thereafter. E. coli populations increased 0.46 to 1.19 logs during fermentation and remained that these levels during overnight cold storage. When unsalted and salted Labneh were inoculated after manufacture, Salmonella populations decreased >2 logs in all samples after 2 days, regardless of storage temperature, with the pathogen no longer detected in 4-day-old samples. Numbers of L. monocytogenes decreased from 2.48 to 3.70 to < 1.00 to 1.95 logs after 2 days with the pathogen persisting up to 15 days in one lot of salted/unsalted Labneh stored at 6 degrees C. E. coli O157:H7 populations decreased from 3.39 to 3.7 to < 1.00 to 2.08 logs during the first 2 days, with the pathogen no longer detected in any 4-day-old samples. Inactivation rates for all three pathogens in Labneh were unrelated to storage temperature or salt content. Unlike L. monocytogenes that persisted up to 15 days in Labneh, rapid inactivation of Salmonella typhimurium DT104 and E. coli O157:H7 suggests that these emerging foodborne pathogens are of less public health concern in traditional Labneh.

Animals↗

The Wisconsin State Laboratory of Hygiene and emerging enteric pathogens.

At the turn of the 20th century, typhoid fever was common in Wisconsin, and was a major impetus for the establishment of the Wisconsin State Laboratory of Hygiene (WSLH) in 1903. By the 1940s, typhoid was virtually eliminated in the United States due to public health measures such as disinfection of drinking water, sewage treatment, pasteurization, and shellfish bed sanitation. However, new food and waterborne pathogens have emerged to take the place of Salmonella Typhi. Infections with non-typhoidal Salmonella strains in the United States have increased almost 10-fold since the 1950s. In the last 20 years, the emergence of foodborne pathogens, such as Escherichia coli O157:H7, Cyclospora cayetanensis, Noroviruses (Norwalk-like viruses), Cryptosporidium parvum, Campylobacter jejuni, Yersinia enterocolitica, and multi-drug-resistant Salmonella, has identified a need for accurate laboratory diagnosis of enteric disease and outbreaks.

Communicable Diseases, Emerging↗

Growth performance and shedding of some pathogenic bacteria in feedlot cattle treated with different growth-promoting agents.

Eighty steers with a mean body weight of 319 kg were used in a study to evaluate the effect of a growth-promoting implant (trenbolone acetate plus estradiol benzoate), monensin, and oxytetracycline on the steer performance and shedding of some foodborne pathogens. The steers were allotted to one of eight treatment combinations according to a randomized complete block design with 16 pens of five animals. Rectal fecal samples were collected before treatment commenced and over a period of more than 24 weeks to study the influence of treatments on the intestinal microbiology of the animals. Results supported the beneficial effect of the hormonal implant on the performance of feedlot steers (average daily gain, feed efficiency, and fat thickness), on carcass characteristics (hot carcass weight, lean yield), and economic value of the carcasses (P < 0.01). The levels of Escherichia coli in feces were not affected by treatments but remained high throughout the study period. Antibiotic-resistant isolates of E. coli were more frequently found as the study progressed but were not associated with any specific treatment. Also independently of treatment, we observed a reduction over time in the shedding of Campylobacter and Yersinia during the feeding period, whereas the shedding of Enterococcus was increased. The results of this study confirmed the beneficial economic effect of growth-promoting agents in beef production and showed that the agents tested did not specifically affect the overall microbial evolution of the animal gut. However, the study also showed, independently of the growth promoter used, the shedding of Campylobacter, Yersinia, and antibiotic-resistant E. coli in the feedlot environment. These bacteria also may be found in the colonic tissue of steers at slaughter and might be a source of carcasses contamination.

Anabolic Agents↗

HACCP and food hygiene in hospitals: knowledge, attitudes, and practices of food-services staff in Calabria, Italy. Collaborative Group.

OBJECTIVES: To determine adherence to Hazard Analysis and Critical Control Points (HACCP) methods and to evaluate knowledge, attitudes, and practices of food-services staff with regard to food hygiene in hospitals. DESIGN: A survey. PARTICIPANTS: Hospital medical directors and food-services staff of 36 hospitals in Calabria, Italy. METHODS: A questionnaire about hospital characteristics, food-services organization, and measures and procedures for the control and prevention of foodborne diseases was sent to medical directors; a questionnaire about demographic and practice characteristics, knowledge, attitudes, and behaviors about control and prevention of foodborne diseases was sent to food-services staff. Multiple logistic regression analysis was performed. RESULTS: Only 54% of the 27 responding hospitals were using the HACCP system and, of those using HACCP, 79% adopted a food-hygiene-practice manual; more than one half already had developed written procedures for food storage, personal hygiene, cleaning and disinfection; one half or less performed microbiological assessment of foods and surfaces. Of the 290 food-services staff who responded, 78.8% were aware of the five leading foodborne pathogens; this knowledge was significantly higher among those with a higher educational level and those who worked in hospitals that had implemented the HACCP system. Younger staff and those who had attended continuing educational courses about food hygiene and hospital foodborne diseases had a significantly higher knowledge of safe temperatures for food storage. A positive attitude toward foodborne-diseases prevention was reported by the great majority, and it was significantly higher in older respondents and in those working in hospitals with a lower number of beds. Only 54.9% of those involved in touching or serving unwrapped raw or cooked foods routinely used gloves during this activity; this practice was significantly greater among younger respondents and in those working in hospitals using HACCP. CONCLUSION: Full implementation of the HACCP system and infection control policies in hospital food services is needed.

Adult↗

Antagonistic action of cells of Lactobacillus delbrueckii subsp. lactis against pathogenic and spoilage microorganisms in fresh meat systems.

Cells of Lactobacillus delbrueckii subsp. lactis RM2-5 were added to various meat model systems that had been inoculated with Escherichia coli O157:H7 or Salmonella Typhimurium to determine whether these lactobacilli were antagonistic to the pathogens during storage at 5 degrees C. Experiments in which L. delbrueckii subsp. lactis RM2-5 was directly applied to the surfaces of beefsteaks resulted in significant (P < 0.05) reductions in the growth of psychrotrophs and coliforms plus a slight decrease in the numbers of E. coli O157:H7 over time relative to those for control samples to which no lactobacilli had been added. Experiments involving the direct application of L. delbrueckii subsp. lactis RM2-5 to the surfaces of freshly slaughtered beef and pork carcass samples inoculated with either E. coli O157:H7 or Salmonella Typhimurium showed significant (P < 0.05) declines in numbers of the pathogens as well as a reduction in the growth of psychrotrophs during storage at 5 degrees C for 6 days. The results of the experiments suggest that lactobacillus cultures have potential for use in an intervention technology for the control of foodborne pathogens, especially on the surfaces of beef and pork carcasses. The results of this study also suggest that an extension of the shelf life of meat can result from the decreased growth of psychrotrophic spoilage organisms.

Animals↗

Foodborne illness primer for physicians and other health care professionals.

Foodborne illness is a serious public health problem. According to the Centers for Disease Control and Prevention (CDC), it is estimated that every year, 76 million Americans get sick, leading to over 300,000 hospitalizations and 5000 deaths. Recent outbreaks underscore Americans' vulnerability to foodborne pathogens. Primarily the very young, the elderly, and the immunocompromised are affected. Recent changes in human demographics and food preferences, changes in food production and distribution systems, and microbial adaptation have led to the emergence of novel as well as traditional foodborne diseases. With increasing travel and trade opportunities, it is not surprising that now there is a greater risk of contracting and spreading a foodborne illness locally, regionally, and even globally. To better recognize, diagnose, treat, and prevent foodborne illnesses, the Foodborne Illness Primer Working Group collaborated to publish the new, updated edition of Diagnosis and Management of Foodborne Illnesses: A Primer for Physicians and Other Health Care Professionals. Physicians and other health care professionals have a critical role in the prevention and control of food-related disease outbreaks. This primer is intended to provide practical and concise information on the diagnosis, treatment, reporting, and prevention of foodborne illnesses.

Centers for Disease Control and Prevention, U.S.↗

Effect of environmental stresses on antibody-based detection of Escherichia coli O157:H7, Salmonella enterica serotype Enteritidis and Listeria monocytogenes.

AIMS: To study the reaction patterns of selected antibodies to Escherichia coli O157:H7, Salmonella enterica serotype Enteritidis and Listeria monocytogenes cells exposed to various environmental stresses. METHODS AND RESULTS: Escherichia coli O157:H7, Salmonella Enteritidis and L. monocytogenes cells subjected to different environmental stress of temperatures (4 and 45 degrees C), NaCl (5.5%), oxidative stress (15 mmol(-1) H2O2), acidic pH (5.5) and ethanol (5%) for 3 h (short-term stress) or for 5 days (long-term stress) were analysed by ELISA and Western blotting. The ELISA results indicated that most stresses caused 12-16% reductions in reaction for anti-E. coli O157:H7 and 20-48% reductions for anti-Salmonella polyclonal antibodies during short-term stress, whereas the most stresses exhibited enhanced reaction (44-100% increase) with the anti-L. monocytogenes polyclonal antibody. During long-term stress exposure to combined stress conditions of pH 5.5, 3.5% NaCl at 12 degrees C or at 4 degrees C, antibody reactions to the three pathogens were highly variable with the combined stress at 4 degrees C showing the most reductions (8-40%). Likewise, there were about 18-59% reductions in antibody reactions with pathogens when cultured in hotdog samples with the combined stress conditions. Western blot analyses of crude cell surface antigens from both short- and long-term stressed cells revealed that the changes in antibody reactions observed in ELISA were either because of repression, expression or possible denaturation of antigens on the surface of cells. CONCLUSIONS: Overall, the antibody reactions were significantly reduced in pathogens exposed to both short- and long-term environmental stresses in culture medium or in meat sample because of expression, repression or denaturation of specific antigens in cells. SIGNIFICANCE AND IMPACT OF THE STUDY: In order to ensure the reliable detection of foodborne pathogens using antibody-based methods, the influence of stress on antibody reactions should be thoroughly examined and understood first as the physiological activities in cells are often altered in response to a stress.

Antibodies, Bacterial↗

A novel role for the LisRK two-component regulatory system in listerial osmotolerance.

Understanding how pathogenic bacteria sense and respond to environmental signals, including those involved in triggering virulence gene expression, is a fundamental biological goal. It is now known that the two-component regulatory system LisRK has a novel role in osmosensing and osmoregulation in the intracellular foodborne pathogen Listeria monocytogenes. Furthermore, htrA, a gene linked to osmotolerance and virulence potential in L. monocytogenes, is now known to be under the transcriptional control of LisRK.

Bacterial Proteins↗

The isolation and detection of Escherichia coli O157 by use of immunomagnetic separation and immunoassay procedures.

The use of immunomagnetic separation (IMS) techniques has been reported to reduce the total test time, and improve the sensitivity, of microbiological tests done on foods. This approach is being adopted in epidemiological investigations into suspected foodborne outbreaks of Escherichia coli O157 infection and has gained acceptance by public health laboratories and the food industry. This study demonstrated the ability of a commercially available IMS procedure, Dynabeads anti-E. coli O157, to enable detection of a few cells of E. coli O157 in 25 g of inoculated minced beef, giving results 1 d earlier than a cultural analysis of similar sensitivity. With correct choice of enrichment broths, IMS may increase isolation rate of E. coli O157 compared to that obtained using conventional cultural methods. It is suggested that this may be due to an increase in relative concentration of E. coli O157 compared with the background microflora present in minced beef, which may reduce reliability of non-IMS detection procedures by masking or mimicking target cells on selective/differential solid media. The use of an immunoassay incorporating an IMS step, EHEC-Tek (Organon-Teknika), enabled detection of a few cells of E. coli O157 in 25 g of minced beef. Comparison of the IMS-ELISA with a standard ELISA procedure (Tecra) indicated the sensitivity of the latter system to be greater, perhaps resulting in the higher isolation rate. The use of a method to reliability isolate and detect extremely low levels of E. coli O157 in a food is necessary to aid reduction in the incidence of this most serious of foodborne pathogens.

Animals↗

[Study on national active monitoring for food borne pathogens and antimicrobial resistance in China 2001].

OBJECTIVE: To survey food borne pathogens and antimicrobial resistance in China. METHODS: A total of 4034 samples of foods (raw meats, raw milk, cooked meats, ice cream, yoghurt, aquatic product and vegetable) were examined for the presence of Escherichia coli O157:H7 Salmonella spp and Listeria monocytogens by national active foodborne pathogens surveillance system. The samples were obtained from 11 provinces in 2001. RESULTS: Approximate 5.50% of the all samples yielded 3 pathogenes, whereas Escherichia coli O157:H7 (0.82%), Salmonella servoars (3.32%) and Listeria monocytogens (1.29%). The most heavy contamination by three food borne pathogens are in raw meat (12.96%). Top seven serotype of the 137 Salmonella isolates are S. derby, S. agona, S. enteritidis, S. reading, S. anatum. S. muenster, S. typhimurium. CONCLUSION: Serotypes and antibiotic resistance patterns of Salmonella isolates are different in 11 provinces. E. coli O157:H7 strains that are isolated from raw meat and cooked meat have VT2, eae, Hly genes. Salmonella and E. coli strains of multidrug resistance were isolated and identified.

Drug Resistance, Multiple↗

Norwalk virus outbreak at a college campus.

An epidemic of nonbacterial gastroenteritis affected nearly 100 students at a college campus in Jefferson County, Alabama. The outbreak closely resembled food poisoning, since there was a rapid occurrence of multiple cases within a short period. Vomiting occurred in 79% and diarrhea in 64%; fever was uncommon. We found a significant association between the illness and the eating of lettuce at a meal one day before the outbreak began. Paired serologic specimens showed evidence of Norwalk virus infection. Twenty acutely ill students had leukocytosis (mean WBC 12,780/cu mm) and lymphopenia--a pattern that may be characteristic of Norwalk virus gastroenteritis. Outbreaks of Norwalk virus infection as well as other nonbacterial gastroenteritis may closely mimic epidemics caused by more familiar foodborne pathogens such as staphylococci.

Alabama↗