[Radioactive contamination of some food products].
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Food Analysis↗
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A simple, rapid and sensitive detection of salmonella in food by polymerase chain reaction.
A polymerase chain reaction (PCR) method was developed for detection of salmonella in food. A set of PCR primers was designed to amplify a 199 bp salmonella-specific DNA fragment derived from a repetitive DNA of Salmonella Weltevreden. The assay detected all 52 most prevalent serovars found in contaminated food in Thailand and no cross-reaction was observed with other non-salmonella organisms. The limit of detection was 1 fg of purified target DNA or five bacteria from pure culture. The detection of artificially contaminated food performed following a 6 h enrichment step was three bacteria per gram and the result was obtained within 4 h.
Animals↗
An analysis of economic costs associated with an outbreak of typhoid fever.
We examined the costs of a typhoid fever outbreak caused by exposures to contaminated food over a 47-day period at a restaurant. For the 49 respondents, the patient-related costs (+215,548) were primarily medical expenses (+183,902) and lost income or productivity (+28,603). The estimated patient-related costs for all 80 outbreak-associated cases was +351,920. Had contaminated food continued to be served, the prevention-related costs (+36,500) would have been offset by patient-related costs (+7,488/day) within 5 days.
Adult↗
[Environmentally induced contamination of foods by carcinogenic hydrocarbons in the GDR and the Hungarian People's Republic].
In the GDR the benzo[a]pyrene (BaP) contents of vegetables grown in areas far from industrial plants range from 0.01 to 2.3 microgram/kg of fresh weight with a mean of 0.43 microgram/kg; and in the Hungarian People's Republic the BaP contents of such vegetables lie between 0.05 and 3.85 microgram/kg with a mean of 0.6 microgram/kg. The BaP contents of vegetables from areas near industrial plants or in the immediate proximity of emitters range from 0.15 to 12.4 microgram/kg (in the GDR) and from 0.05 to 19.6 microgram/kg (in the Hungarian People's Republic), being markedly superior to the values obtained with comparable vegetables from areas far from industrial plants. The BaP contents of samples from the Hungarian People's Republic collected near a relatively new petrochemical plant were 3.5 times as high as those of samples collected in areas far from industrial plants; and the BaP contents obtained with samples collected in the proximity of an old petrochemical plant were 8 times as high as those observed with samples collected in areas far from industrial plants. The contamination depends strongly upon the type of emitter. Samples collected in the GDR in the immediate proximity of coal-preparation plants (such as tar extraction, coking or carbon black plants) contained BaP contents 10 to 100 times as high as those found in samples collected in areas far from industrial plants. Targeted measures aiming at diminishing air pollution will widely reduce the contamination of harvested crops with cancerogenic hydrocarbons.
Carcinogens↗
Foodborne and waterborne parasites.
More than 72 species of protozoan and helminth parasites can reach humans by food and water, and most of these infections are zoonoses. Some parasites show a cosmopolitan distribution, others a more restricted distribution due to their complex life cycles, which need the presence of one or more intermediate hosts. Of this large number of pathogens, only Toxoplasma gondii can be transmitted to humans by two different ways, i.e., by cysts present in infected meat and by oocysts contaminating food and water. Eleven helminthic species (Taenia saginata, Taenia solium, Taenia asiatica, Trichinella spiralis, Tr. nativa, Tr. britovi, Tr. pseudospiralis, Tr. murrelli, Tr nelsoni, Tr. papuae and Tr. zimbabwensis) can grow in meat of different animal species and can be transmitted to humans by the consumption of raw meat or meat products. Twenty trematode species, four cestode species and seven nematode species can infect humans through the consumption of raw sea- and/or fresh-water food (fishes, molluscs, frogs, tadpoles, camarons, crayfishes). Six species of Cryptosporidium, Isospora belli, Cyclospora cayetanensis, Giardia duodenalis and Entamoeba histolytica/E. dispar can contaminate food and water. Among the helminths, seven trematode species, seven cestode species and five species of nematodes can reach humans by contaminated food and water. Diagnostic and detection methods that can be carried out routinely on food and water samples are available only for few parasites (Cryptosporidium sp., Giardia sp., Anisakidae, Trichinella sp., Taenia sp.), i.e., for parasites which represent a risk to human populations living in industrialised countries. The majority of food and waterborne infections of parasitic origin are related to poverty, low sanitation, and old food habits.
Animals↗
Epidemiological aspects in food safety.
The rapid growth of international trade in food products has resulted in increased hazards from trans-boundary foodborne infections and intoxication. Therefore, the development of multinational surveillance and registration of foodborne diseases or food contamination, of both biological and chemical origin, is of utmost importance for their prevention and control. Recognizing the importance of accurate and adequate epidemiological data for decision making with respect to priorities, resources and management, the World Health Organization (WHO) launched in 1976 the Joint UNEP/FAO/WHO Food Contamination Monitoring Programme (GEMS/Food) and in 1980 the surveillance programme for control of foodborne infections and intoxications in Europe. Although the response of participating countries in both programmes was very positive, many questions have arisen during this period which require further improvements through national and international action. Monitoring and surveillance of food contamination and foodborne infections and intoxications is a multidisciplinary process and requires the active involvement of experts in medical and veterinary food hygiene, food chemistry and epidemiology. Since health risk management with respect to food safety is frequently delegated to different authorities, much better coordination between the sectors is needed in order to improve epidemiological analysis at national and international level. The purpose of this paper is to review the WHO regional programme for prevention and control of foodborne infections and intoxications in the light of accumulated experience and to discuss plans and possibilities for further improvements through national and international action in the 1990s.
Disease Outbreaks↗
Argemone oil induced cellular damage in the reproductive tissues of transgenic Drosophila melanogaster: protective role of 70 kDa heat shock protein.
We explored the reproductive toxicity of argemone oil and its principal alkaloid fraction in transgenic Drosophila melanogaster (hsp70-lacZ) Bg(9). The toxicity of argemone oil has been attributed to two of its physiologically active benzophenanthridine alkaloids, sanguinarine and dihydrosanguinarine. Freshly eclosed first instar larvae of transgenic Drosophila melanogaster were transferred to different concentrations of argemone oil and its alkaloid fraction contaminated food. Virgin flies that eclosed from the contaminated food were pair-mated to look into the effect on reproduction. The study was further extended by investigating hsp70 expression and tissue damage in larval gonads, genital discs, and reproductive organs of adult fly. Our results showed that argemone oil was more cytotoxic than its principal alkaloid fraction. Moreover, it was the male fly that was more affected compared to its opposite number. The accessory glands of male reproductive system of the fly, which did not express hsp70, exhibited severe damage as evidenced by Trypan blue staining. This prompted us to explore the ultrastructural morphology of the gland, which showed acute signs of necrosis in both the cell types as evident by necrotic nuclei, higher vacuolization, and disorganized endoplasmic reticulum, decrease in the number of Golgi vesicles and disorganized, loosely packed filamentous structures in the lumen of the accessory gland, at the higher concentrations of the adulterant. The study showed the reproductive toxicity of argemone oil and its alkaloid fraction in transgenic Drosophila melanogaster and further confirmed the cytoprotective role of hsp70.
Alkaloids↗
Importance of international cooperation in food safety.
All countries need to ensure that national food supplies are safe, of good quality and available in adequate amounts at affordable prices to ensure good nutrition and health for all population groups. The enforcement of food standards by efficient national food control authorities in domestic markets and at the points of import and export has been increasingly recognized as a means of raising the value of exported goods by reducing the number of rejected or reconditioned consignments, and of ensuring the safety of the food and its acceptability by the final consumer. However, those national efforts have sometimes induced some non-tariff barriers to food trade and distribution. In addition, new developments in the technologies of food production, processing and marketing pose a new challenge to ensure safety of food. The strengthening of national food control infrastructures in particular in developing countries including the strengthening of staff capabilities, the need for harmonization of food at international levels, the need for collection and exchange of data on food control and food contamination issues are essential elements to ensure food safety in the world. International cooperation has an important role to play in achieving these essential elements.
Food Additives↗
Circumstances associated with the contamination of food by aflatoxin in a high primary liver cancer area.
The variable incidence of primary liver cancer has been shown to be related to the average daily intake of aflatoxin in various parts of the world. This study was made to detect and report strategic points of contamination of foodstuffs in the region with the highest known incidence of liver cancer. Methods of food production, harvesting, storage and preparation were examined, and defects which promote fungus growth on food were found at each stage. Most meals consisted of a single dish with three basic ingredients -- a protein, bulk carbohydrate and green vegetables. Groundnuts were the main source of protein, but were also the main cause of aflatoxin contamination, since casual traditional methods of agriculture are not suited to the production of this exotic crop. Aflatoxin production appears to occur in the main sources of carbohydrate, such as cassava and maize, during storage. Leaves of various kinds provide substitutes for green vegetables and common methods of handling the crop promote fungal growth. Western-type foods had a particularly low aflatoxin content, or were free of it. Education and economic opportunities external to the subsistence economy structure are contributing to the westerisation of some living habits, a process believed to be responsible for the observed decrease in the incidence of primary liver cancer. Current knowledge indicates that a pertinent but simple educational programme could further markedly reduce the incidence of the disease.
Aflatoxins↗
Formation of heterocyclic amines during meat extract processing and cooking.
Standardized biological in vitro systems and in particular those used for cancer prediction are being used to monitor the development of food products in order to ensure the absence of potential mutagens or carcinogens. Maillard reactions occurring during meat extract production was followed in order to reduce the formation of heterocyclic amines. Possibilities to reduce the content of heterocyclic amines during meat extract processing have been proposed. However, several aspects, such as interaction with food-borne mutagen or carcinogen inhibitors, keeping quality, and organoleptic properties have also been taken into consideration. Whenever possible, food contaminants must be analytically determined and compared to total intake exposure and tolerated levels of other comparable food contaminants to establish realistic "tolerated" contamination levels.
Amines↗
PCR detection of Listeria monocytogenes: a study of multiple factors affecting sensitivity.
AIMS: To test, under comparable conditions, several parameters affecting sensitivity of PCR detection in order to establish a PCR procedure suitable for the routine detection of Listeria monocytogenes in food. METHODS AND RESULTS: Beef samples artificially inoculated were used to determine sensitivity of PCR detection under different parameters. As few as 1 CFU g(-1) were detected by DNA extraction using a DNeasy Tissue Kit (Qiagen GmhH, Hilden, Germany) of 1 ml aliquot and PCR amplification with primers directed to the hlyA gene. This PCR protocol was applied in 60 naturally contaminated foods, comparing two enrichment procedures with the traditional culture method. The highest number of positives was recorded by PCR following a 24-h pre-enrichment step at 30 degrees C and a 24-h enrichment step at 37 degrees C. Afterwards, it was applied in 217 naturally contaminated foods and 56 of them tested positive for L. monocytogenes in which only 17 tested positive using the culture method. CONCLUSIONS: The PCR procedure described has proved to be a rapid and sensitive method suitable for the routine analysis of different types of food. SIGNIFICANCE AND IMPACT OF THE STUDY: The method proposed for the detection of L. monocytogenes, has been validated in naturally contaminated food and is suitable to implement in the food industry.
Animals↗
AnDiaTec Salmonella sp. PCR-ELISA for analysis of food samples.
A commercially available PCR kit (AnDiaTec Salmonella sp. PCR-ELISA) was developed and evaluated for the detection of Salmonella sp. in food samples. The test is based on PCR amplification and hybridization of the amplified DNA to a microtiter plate followed by the detection of PCR product in the manner of an enzyme-linked immunosorbent assay test. The sensitivity and specificity were evaluated first with Salmonella pure cultures and artificially contaminated food samples, including food types for which an inhibition of the PCR reaction was expected. Both experiments proved a very good sensitivity, specificity, and reliability of the test with a very broad range of food types. In a second evaluation study, more than 1,100 food samples of different types were tested in parallel with the PCR method and with the International Standardization Organization 6579 bacteriological reference method. The results of this evaluation study and the results from other experiments on dilutions of artificially contaminated food samples led to the establishment of a positive-negative cutoff value (optical density at 450 nm of more than 0.9) with respect to the conventional bacteriological method. Using this positive-negative cutoff, 98% agreement to the bacteriological method was obtained.
DNA, Bacterial↗
An update on oral anaphylaxis from mite ingestion.
OBJECTIVE: To review systemic reactions due to the oral ingestion of mites. DATA SOURCES: We performed a MEDLINE search of peer-reviewed research articles published between 1993 and 2004 relevant to the subject of anaphylactic reactions to mite-contaminated foods. STUDY SELECTION: Recent studies that emphasized the potentially life-threatening nature of anaphylactic reactions, responsible foodstuffs and mites, populations at risk, and pathogenesis were selected for inclusion in this review. RESULTS: Although relatively few new cases of oral mite anaphylaxis are reported in the literature, we speculate that this clinical condition is occurring more frequently than realized in many geographic locations, and only the suspicion of an informed physician can contribute to its diagnosis and prevention. Oral anaphylaxis from mite-contaminated foods may be lethal if not promptly recognized and treated, and some preventive measures may be helpful for individuals at risk. Frequent cross-reactions among domestic, storage, and phytophagous mites explain the increased risk of oral mite anaphylaxis in sensitive patients living in both urban and rural areas. The enzymatic activity of some mite allergens contributes to the pathogenesis of this syndrome by means of mucosal damage and enhanced allergen absorption through the oral route. CONCLUSIONS: Oral mite anaphylaxis is a severe, potentially lethal allergic condition that occurs in many countries and is frequently undiagnosed. Early recognition may lead to the implementation of simple prophylactic measures in at-risk populations of allergic patients.
Allergens↗
Negative chemical ionization studied of human and food chain contamination with xenobiotic chemicals.
Negative chemical ionization mass spectrometry with a mixture of isobutane, methylene chloride, and oxygen as the reagent gas has been used to explore contamination of environmental substrates with xenobiotic chemicals. The substrates in question, fish tissue, human seminal plasma, and human adipose tissue, were cleaned up by one of the following three cleanup procedures: (1) continuous liquid-liquid extraction steam distillation; (2) gel-permeation chromatography; and (3) adsorption on activated carbon followed by elution with toluene. The third procedure was used only for the examination of planar polychlorinated aromatic hydrocarbons in environmental samples. Using these techniques, we have found evidence for contamination of fish samples with polychloronaphthalenes, polychlorostyrenes, polychlorobiphenyls, polychlorodibenzofurans, and polychlorodibenzodioxins among other chemicals. The polychlorodibenzodioxins appeared only in the spectra of extracts of fish obtained from the Tittabawassee River at Midland Michigan. The polychlorodibenzofuran ions appeared in NCI mass spectra of fish that were significantly contaminated (above 2 ppm) with polychlorobiphenyls. Toxic substances occurring in human seminal plasma included pentachlorophenol, hexachlorobenzene, DDT metabolites, and polychlorobiphenyls. We have investigated toxic substances in human seminal plasma because of the apparent decrease in sperm density in U.S. males over the last 30 years. Results of screening human adipose tissue for contamination with xenobiotic chemicals have been largely coincident with result of the EPA human monitoring program. Polychlorobiphenyls, DDT metabolites, nonachlor, and chlordane have appeared in most samples examined. Detection limits for all of these chemicals were of the order of 1 ppb.
Adipose Tissue↗
Shiga toxin-producing Escherichia coli isolates from cases of human disease show enhanced adherence to intestinal epithelial (Henle 407) cells.
Shiga toxin-producing Escherichia coli (STEC) strains are a diverse group of organisms which are known to cause diarrhea and hemorrhagic colitis in humans. We have recently described a large food-borne outbreak of STEC disease caused by contaminated semidry fermented sausage (A. W. Paton, R. Ratcliff, R. M. Doyle, J. Seymour-Murray, D. Davos, J. A. Lanser, and J. C. Paton, J. Clin. Microbiol. 34:1622-1627, 1996). STEC strains belonging to several O serotypes were isolated from the contaminated food source, but of these, only a subset were isolated from patients with diarrhea or hemolytic-uremic syndrome (HUS). In the present study, we characterized these STEC isolates with respect to the presence of putative virulence-associated genes and the capacity to adhere to a human intestinal epithelial cell line (Henle 407). The O111:H- STEC strain 95NR1 (isolated from one of the outbreak HUS patients) was shown to adhere to Henle 407 cells in a dose-dependent, mannose-resistant fashion. Microscopic examination revealed a diffuse pattern of adherence for this as well as several other STEC strains. Interestingly, the adherence of STEC strains from HUS cases (both outbreak related and sporadic) was significantly greater than that of STEC strains found in the contaminated food source but not found in any patients. These studies support the hypothesis that an enhanced capacity to adhere to intestinal cells is one of the factors which distinguishes human-virulent STEC strains from those of lesser clinical significance.
Animals↗
Several sporadic outbreaks of El Tor cholera in Sunpathong, Chiang Mai, September-October, 1987.
From September through October 1987, a cholera outbreak involving 59 cases of biotype El Tor, serotype Inaba occurred in Sunpathong district, Chiang Mai. No cases died. Twenty-seven cases were males and 32 were females. The age ranged between 4 months and 85 years, with a median of 36 years. The outbreak affected 7 small communities, and showed different vehicles of infection. Six housewives and one girl were infected with cholera in the first localized outbreak. The transmission of infection appeared due to the consumption of packed food contaminated by an infected food handler. In the second localized outbreak, 6 young males acquired cholera after eating uncooked fish harvested from a canal contaminated with cholera organisms. Another outbreak of cholera with 24 culture-confirmed cases occurred among guests at a funeral held in one rural village. The source of infection was traced to uncooked pork contaminated from an infected butcher: Early detection of infected persons, rapid identification of possible vehicles of transmission, and prompt implementation of control measures effectively curtailed the extension of these outbreaks.
Adolescent↗
A field study of the microbiological quality of fresh produce of domestic and Mexican origin.
Produce is responsible for an increasingly larger proportion of foodborne disease outbreaks. In particular, the globalization of the food supply may introduce new food safety risks and allow widespread distribution of contaminated food, particularly produce. The objectives of this study were to: (i) compare the overall quality of domestic and Mexican produce throughout the packing process; (ii) examine changes in microbiological quality of both domestic and Mexican produce at each stage of production and processing; and (iii) evaluate the prevalence of select pathogens on fresh produce, including leafy green, herbs, melons, and vegetables. Furthermore, we also sought to characterize the antibiotic resistance profiles of Enterococcus faecium and Enterococcus faecalis strains isolated from fresh produce. A total of 466 produce and matching environmental swab samples was collected from various locations in packing sheds in the southern US from November 2002 through December 2003. These samples were assayed by enumerative tests for total aerobic bacteria (APC), total coliforms, total Enterococcus, and E. coli. Produce samples were also analyzed for the presence of Salmonella, Listeria monocytogenes, Shigella, and E. coli O157:H7. A total of 112 E. faecium and E. faecalis isolates were further screened for antibiotic resistance using a panel of seventeen antibiotics. Overall, the microbiological quality of fresh produce ranged from 4.0 to 7.9 log(10) CFU/g (APC); less than 1.0 log(10) to 4.5 log(10) CFU/g (coliforms); less than 1.0 log(10) to 4.0 log(10) CFU/g (E. coli); and less than 1.0 log(10) to 5.4 log(10) CFU/g (Enterococcus). No Salmonella, Shigella, or E. coli O157:H7 were detected from the 466 25-g produce samples tested. However, three domestic cabbage samples were found to be positive for L. monocytogenes. Of the Enterococcus isolates, E. faecium had a higher degree of resistance to antibiotics in general, while Enterococcus spp. isolated from Mexican produce had a higher degree of antibiotic resistance when compared to strains isolated from produce samples of domestic origin. Despite increased attention to the role of imported produce in foodborne disease, this study does not support the assumption that domestic produce is of higher microbial quality than Mexican produce.
Anti-Bacterial Agents↗
Evaluation of certain food additives and contaminants.
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Animals↗