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PubMedDate not supplied

[Molecular characterization of Listeria monocytogenes and the significance for food hygiene].

Research on the pathogen Listeria monocytogenes is a key issue both for the clinical and the food microbiologist owing to the unique pathway of infection and the exposure of humans via contaminated foods. Although, in Austria, the incidence of listeriosis is about 870-fold lower than the incidence for Salmonella infection, the food law manages both foodborne pathogens with a comparable stringency. The current risk management is based on the assumption that environmental L. monocytogenes isolates, from which the pool of "foodborne" isolates is recruited, are of similar pathogenicity compared to clinical and outbreak isolates. This verdict became doubted in the recent years. Characterization of L. monocytogenes by virulence gene sequencing, virulence studies in vivo and in vitro and by molecular typing was considerably stimulating the discussion on virulence variability in L. monocytogenes. This article provides insights in the value of epidemiological follow-up studies by presenting a typing study on 15 cases of listeriosis observed in a district hospital in Turkey. Furthermore results from typing L. monocytogenes either by virulence gene sequencing, mismatch amplification mutation assay or by pulsed field gel electrophoresis are discussed. The close interaction of molecular microbiology with food microbiology both in applied and basic science is currently creating a new discipline of molecular food microbiology. We are convinced that veterinary medicine will contribute to this exiting development in a fruitful way.

Animals↗
PubMed2002

Resistance of domestic cats to a US sheep scrapie agent by intracerebral route.

Feline spongiform encephalopathy (FSE) is thought to have resulted from consumption of food contaminated with bovine spongiform encephalopathy and the latter is believed to result from the consumption of food contaminated with scrapie. However, no direct experimental documentation exists to indicate that the scrapie agent is capable of amplifying in cats, and, therefore, crossing the species barrier. During 1979, 6 cats ranging in age from 3.5 to 18 months were intracerebrally inoculated with sheep scrapie (inoculum G-639-PP) and were observed for an extended period. Inoculated cats did not develop neurologic disease, and microscopic lesions of spongiform encephalopathy were not evident. Immunohistochemistry and Western blot techniques failed to detect the abnormal form of prion protein (PrP(res)). These results indicate that the sheep scrapie agent (G-639-PP) used in this study was not capable of amplifying in cats and therefore was unable to cross the species barrier to produce FSE.

Animals↗
PubMed2003

Food safety and risk assessment: naturally occurring potential toxicants and anti-nutritive compounds in plant foods.

The centralisation and globalisation of the world food supply presents opportunities for massive epidemics of food borne illness. Food processing generally decreases exposure to naturally occurring toxicants. A significant number of deaths are caused in both developed and developing countries from the consumption of naturally occurring toxicants and this exceeds the numbers attributable to artificial food contaminants and pollutants. The risk posed by naturally occurring toxicants is greater in developing countries where food choice and facilities for food processing are limited. The main risk in developed countries is from food important from areas where food safety controls are inadequate. Toxins derived from marine algae present a specific threat to health especially as seafood is being traded from areas where poisoning by algal toxins is known to occur. A systematic approach to food safety using HACCP methodology and identity preservation of the food are crucial in the prevention of food related illness. There is also a need for international agreed standards for tolerable levels of naturally occurring toxicants in foodstuffs but these should derived not be set unreasonably low as this would threaten food security in developing countries. The occurrence of a number of fatalities in developing countries among people consuming herbal teas and dietary supplements underscores the need to assess the safety of these products before they are placed on the market.

Consumer Product Safety↗
PubMed1997

Detection of Escherichia cole O157 in French food samples using an immunomagnetic separation method and the VIDAS E. coli O157.

Two commercially available screening methods, an automated enzyme-linked fluorescent immunoassay (VIDAS E. coli O157) and an immunomagnetic separation followed by culture onto cefixime tellurite sorbitol MacConkey agar (CT-SMAC), were compared for detection of Escherichia coli O157 in naturally and artificially contaminated food samples. A total of 250 naturally contaminated food samples, including raw milk cheeses, poultry, raw sausages and ground beef retail samples, were examined. Four poultry, one raw sausage and one ground beef sample were found to be positive for E. coli O157 by both methods. Of the six positive samples, five were shown to contain sorbitol-positive, O157-positive, H7-negative, motile and non-verotoxin-producing E. coli.

Cheese↗
PubMed2006

Determination of resorcylic acid lactones in biological samples by GC-MS. Discrimination between illegal use and contamination with fusarium toxins.

An EU project, FAIR5-CT-1997-3443, has been undertaken to distinguish illegal use of zeranol from consumption of food contaminated with Fusarium spp. toxin. One of the tasks was development of screening and confirmatory methods of analysis. This paper describes a new method based on two-step clean-up and GC-MS analysis. The first clean-up step is matrix-dependant; the second is applicable to both urine and meat. The MS is operated in negative chemical ionisation mode. The method is quantitative for zeranol and taleranol, alpha- and beta-zearalenol, and zearalenone and qualitative for zearalanone. Validation was performed according to the latest EU performance criteria (Commission Decision 2002/657). For analysis of urine CC(alpha) and CC(beta) for the method (microg L(-1)) were 0.06-0.11 for zeranol, 0.07-0.12 for taleranol, 0.07-0.11 for alpha-zearalenol, 0.21-0.36 for beta-zearalenol, 0.35-0.60 for zearalenone, and 0.19-0.33 zearalanone. Within-laboratory reproducibility was 16.2, 11.2, 31.9, 30.1, 26.6, and 54.2% for zeranol, taleranol, alpha-zearalenol, beta-zearalenol, zearalenone, and zearalanone, respectively. It was found that all the compounds are stable in urine at -20 degrees C for at least a year. Part of the validation program was organisation of a small proficiency study (ringtest) and a correlation study with an LC-MS-MS method developed by the Veterinary Science Division (VSD; Belfast, UK-NI). This study showed there was good correlation between results from both laboratories. The method can be used for quantitative analysis discriminating illegal use of zeranol from consumption of zearalenone-contaminated food.

Animals↗
PubMed2006

Injector-internal thermal desorption from edible oils performed by programmed temperature vaporizing (PTV) injection.

Injector-internal thermal desorption is a promising technique for the analysis of a wide range of food components (e.g., flavors) or food contaminants (e.g., solvent residues, pesticides, or migrants from packaging materials) in edible oils and fats or fatty food extracts. Separation from the fatty matrix occurs during injection. Using programmed temperature vaporizing (PTV) injection, the oily sample or sample extract was deposited on a small pack of glass wool from which the components of interest were evaporated and transferred into the column in splitless mode, leaving behind the bulk of the matrix. Towards the end of the analysis, the oil was removed by heating out the injector and backflushing the precolumn. The optimization dealt with the gas supply configuration enabling backflush, the injector temperature program (sample deposition, desorption, and heating out), separation of the sample liquid from the syringe needle and positioning it on a support, deactivation of the support surface, holding the plug of fused silica wool by a steel wire, and the analytical sequence maintaining adsorptivity at the desorption site low. It was performed for a mixture of poly(vinyl chloride) (PVC) plasticizers in oil or fatty food. Using MS in SIM, the detection limit was below 0.1 mg/kg for plasticizers forming single peaks and 1 mg/kg for mixtures like diisodecyl phthalate. For plasticizers, RSDs of the concentrations were below 10%; for the slip agents, oleamide and erucamide, it was 12%. The method of incorporating PTV injection was used for about one year for determining the migration from the gaskets of lids for glass jars into oily foods.

Dietary Fats, Unsaturated↗
PubMed2005

[Establishment of standards and specifications for chemical substances in foods and evaluation of exposure to maintain food safety].

Currently, consumers are very anxious about many chemical substances contained in foods. To maintain food safety, the Ministry of Health, Labour and Welfare of Japan establishes standards and specifications on toxic chemical substances in foods, establishes analytical methods for surveillance, and investigates the daily dietary intake of food contaminants every year. This paper describes what sorts of standards and specifications for toxic chemical substances in foods have been established and what kinds of research on daily dietary intake have been performed. As the subjects for description, pesticide residues, toxic metals, dioxins, acrylamide, food additives, genetically modified food products, so-called health foods, and food allergens are included.

Allergens↗
PubMed1999

Trans,trans-muconic acid, a biological indicator to low levels of environmental benzene: some aspects of its specificity.

BACKGROUND: The specificity of trans,trans-muconic acid (MA) as a biomarker of exposure to low benzene levels and the role of sorbic acid (SA) as a confounding factor were evaluated. MA, a urinary ring-opened metabolite of benzene, has been recently proposed for the biological monitoring of populations exposed to low levels of this chemical. The usual presence of MA in urine of non-occupationally exposed people is generally attributed to benzene world-wide contamination (mainly by smoking habits, urban pollution, and maybe by food contamination). However, the scientific literature reveals that the common food preservative and fungistatic agent SA is converted into MA though in trace amounts. METHODS: Urinary benzene and MA before and after administration of SA were measured in smokers and non-smokers. Benzene dissolved in urine was analyzed injecting a headspace sample in a gas-chromatografic system. Urinary MA was measured by means of a HPLC apparatus. RESULTS: The mean background values of MA were about 60 mg/L (or 50 mg/g creat.); after experimental administration of SA (447 mg), the mean urinary MA concentration became more than 20 times higher. The biotransformation rates of SA into MA after ingestion of 447 mg of SA ranged from 0.05 to 0.51%. The ratio between unmetabolized benzene in the two groups of smokers and non-smokers was significantly different from the ratio between MA in the same two groups. DISCUSSION: Other sources of MA excretion, different from benzene, influence the urinary concentration of the metabolite: only 25% of MA background values can be attributed to benzene. The urinary MA induced by 100 mg of ingested MA is 77% of that expected after an 8-hour benzene exposure to 0.5 ppm (current threshold limit value according to ACGIH). In conclusion, MA is not a sufficiently specific biomarker of low benzene exposure; a significant effect of SA ingestion is predictable.

Adult↗
PubMed2006

Canadian listeriosis reference service.

Listeria monocytogenes, a psychrotrophic organism capable of growing at refrigeration temperatures, is of major concern in extended shelf life, refrigerated foods. Considering that as much as 80-90% of human listeriosis cases are linked to the ingestion of contaminated food, human cases are predominantly seen in high-risk individuals, including organ-transplant recipients, patients with AIDS and HIV-infected individuals, pregnant women, cancer patients, and the elderly. In 2001, the Canadian Listeriosis Reference Service (LRS) was created by the Bureau of Microbial Hazards (Health Canada) and the National Microbiology Laboratory (now part of the Public Health Agency of Canada). Major goals of the LRS include investigation of listeriosis cases and maintenance of a national collection of isolates. The LRS intends to create a comprehensive molecular epidemiological database of all isolates in Canada for use as a resource for outbreak investigations, research and other microbiological investigations. The PFGE profiles are being established and stored for clinical, food, environmental, and possibly animal strains of L. monocytogenes. The LRS pursues research activities for investigation and implementation of other molecular methods for characterizing L. monocytogenes isolates. Ribotyping, Multi-locus Sequence Typing (MLST), Variable Number of Tandem Repeats (VNTR), Multi-locus virulence sequence typing (MLVA), microarray- based technologies and sequence-based typing schemes, are being investigated on selected diversity sets. The LRS has also used PFGE typing for outbreak investigations. The molecular epidemiological data, timely coordination and exchange of information should help to reduce the incidence of listeriosis in Canada. In Canada, listeriosis is not a national notifiable disease, except for the province of Quebec, where it has been since 1999. The LRS, Canadian Public Health Laboratory Network, and federal epidemiologists are currently working on making human listeriosis notifiable throughout Canada.

Canada↗
PubMedDate not supplied

Reveal for Salmonella test system.

The Reveal for Salmonella (RSS) test system is a presumptive qualitative test that detects the presence of Salmonella organisms in foods within 21 h total testing time, allowing the user to release negative products 24 h earlier than when using other rapid test kits. Foods are enriched with a proprietary resuscitation medium called Revive and then selectively enriched with either Selenite Cystine or Rappaport-Vassiliadis selective media. The enriched culture is used to inoculate the RSS detection device, which initiates a lateral flow through a reagent zone containing anti-Salmonella antibodies conjugated to colloidal gold particles that capture antigens present in the culture. The antigen-antibody complex migrates farther and is captured by an additional anti-Salmonella antibody, causing the colloidal gold to precipitate and form a visual line, indicating a positive result. A procedural control line also will form regardless of the presence of Salmonella organisms to indicate the test is working properly. Existing AOAC Official Methods for Salmonella organisms require a 48 h enrichment before testing. Hence, a food product has to be held before release, adding extra cost to the company and the consumer. The RSS test system was evaluated by quantitative spiking studies. Although AOAC encourages inclusion of naturally contaminated foods, almost all microbiological AOAC validation studies have been performed with artificially contaminated foods for absolute control over the study. The RSS test system is designed to test many food types for Salmonella organisms and has a limit of detection of 5-10 colony-forming units (cfu)/25 g with a false-negative rate of < 1% and a false-positive rate of < 5.0%. It showed an 81% overall agreement with the traditional procedure of the U.S. Department of Agriculture's Food Safety Inspection Service.

Animals↗
PubMed2006

Validated PCR assay for the routine detection of Salmonella in food.

We developed a rapid and reliable PCR assay with genus-specific primers for the detection of Salmonella in food samples. With these primers, no primer-specific amplicons were detected when challenged with cultures of microorganisms other than salmonellae, and positive results, i.e., Salmonella-specific bands, were obtained with pure cultures of all 125 Salmonella isolates tested, which represented 100 serovars. The PCR assay was optimized using both pure cultures and artificially inoculated food samples. The assay results were compared with those of the Australian standard culture methods, using more than 500 "naturally" contaminated food samples, over a period of 9 years. Food samples were subjected to nonselective preenrichment in buffered peptone water followed by selective enrichment in Rappaport Vassiliadis (RV) broth and mannitol selenite cystine (MSC) broth. A simple sample preparation method was developed based on concentrating bacterial cells from 1 ml of RV or MSC broths. The PCR results were in perfect agreement with the results of the standard culture methods; no false-positive or false-negative results were obtained. However, the PCR assay was extremely rapid, and results could be obtained within 4 h of testing of enrichment broths.

Australia↗
PubMed2004

Detection of Bacillus species in selected meals from an apulian catering service.

The authors have started a microbiological survey of the meals given in a factory canteen in the town of Bari with the evaluation of food contamination from the bacteria of the genus Bacillus. In the examined meals, all the detected Bacillus species have the potential to cause food-borne illnesses, even if the relatively low bacterial counts are not dangerous for healthy consumers. The study underlines the need of guidelines to enstablish which levels of food contamination are significant potential risks to all community catering service users.

Bacillus↗
PubMed2003

Comparison of predictive models for growth of parent and green fluorescent protein-producing strains of Salmonella.

The green fluorescent protein (GFP) from the jellyfish Aequorea victoria can be expressed in, and used to follow the fate of, Salmonella in microbiologically complex ecosystems such as food. As a first step in the evaluation of GFP as a tool for the development of predictive models for naturally contaminated food, the present study was undertaken to compare the growth kinetics of parent and GFP-producing strains of Salmonella. A previously established sterile chicken burger model system was used to compare the growth kinetics of stationary-phase cells of parent and GFP strains of Salmonella Enteritidis, Salmonella Typhimurium, and Salmonella Dublin. Growth curves for constant temperatures from 10 to 48 degrees C were fit to a two- or three-phase linear model to determine lag time, specific growth rate, and maximum population density. Secondary models for the growth parameters as a function of temperature were generated and compared between the parent and GFP strain pairs. The effects of GFP on the three growth parameters were significant and were affected by serotype and incubation temperature. The expression of GFP reduced specific growth rate and maximum population density while having only a small effect on the lag times of the three serotypes. The results of this study indicate that the growth kinetics of the GFP strains tested were different from those of the parent strains and thus would not be good marker strains for the development of predictive models for naturally contaminated food.

Animals↗
PubMedDate not supplied

[Sudden death of twins: botulism because of contamination by pap vegetables].

Botulism is caused by the blockage of the neural transmission in the cholinergic synapses by botulinum neurotoxin (BoNT) which is produced by Clostridium botulinum or other Clostridia. The classic form of botulism occurs after the ingestion of food contaminated by BoNT. The course of the infection can be asymptomatic, mild with subtle paralysis ("failure to thrive") oder severe with generalized paralysis ("floppy infant"). Infected infants can also die sudden and unexpectedly. These deaths often are attributed to Sudden Infant Death Syndrome (SIDS), unless a thorough postmortem examination reveals Botulism. The rate of fatal Botulism falsely attributed to SIDS is not known, because it is difficult in most cases to show the causal relationship between contamination, disease and death. We report the sudden and unexpected simultaneous death of twins of 22 months which could be attributed to Botulism. Contamination of food, colonization of the gut by Clostridia and infection with specific pathomorphological changes could be proven. The initial suspicion of infanticide could be excluded. lt could be shown, that Botulism is a potential cause of simultaneous unexpected deaths in twins.

Botulinum Toxins↗
PubMed2004

Microbiological evaluation of foodservice contact surfaces in Iowa assisted-living facilities.

A study of 40 assisted-living facilities in Iowa was conducted to assess the microbiological quality of food-contact surfaces (work tables/counters, cooking equipment such as mixing bowls, and cutting boards) and a surface that could cross-contaminate food (refrigerator or freezer handles) to determine the effectiveness of cleaning and sanitation. Standards were set for foodservice for aerobic plate count, Enterobacteriaceae, and Staphylococcus aureus . Two facilities met standards for all five surfaces for each of the three tests. Fewer facilities met the standard for aerobic plate count than for the other two tests, and nearly three fourths of the facilities failed to meet the aerobic plate count for cutting boards. Critically, cross-contamination from these surfaces could result in contamination of food; thus, attention needs to be given to training and supervision to ensure proper hand washing and appropriate cleaning and sanitation procedures to reduce or eliminate cross-contamination.

Assisted Living Facilities↗
PubMed2005

Coagulase-positive Staphylococci and Staphylococcus aureus in food products marketed in Italy.

Staphylococcus aureus is a very common organism capable of producing several enterotoxins (SEs) that cause intoxication symptoms of varying intensity in humans when ingested through contaminated food. This paper reports the results of an investigation on the presence of Coagulase-Positive Staphylococci (CPS) and S. aureus in several food products marketed in Italy and on food contact surface swabs sampled from the food industry. A total of 11,384 samples were examined and 1971 of them (17.3%) were found to contain CPS. The assays performed on 541 CPS strains led to the identification of 537 S. aureus strains on which characterization of type A, B, C and D staphylococcal enterotoxins (SEA, SEB, SEC and SED) was performed. A total of 298 S. aureus strains (55.5%) produced one or more SEs: 33.9% of the strains produced SEC, 26.5% SEA, 20.5% SEA+SED, 13.4% SED, 2.7% SEB, 1.7% SEA+SEB, 0.7% SEC+SED and 0.3% produced SEA+SEC and SEB+SEC. The investigation highlighted that these organisms are very common and constitute a potential risk for consumers' health.

Coagulase↗
PubMed2000

Comparison of three enrichment media for the isolation of Campylobacter spp. from foods.

AIM: This study compared the performance of three Campylobacter enrichment broths: Bolton broth (BB), Campylobacter Enrichment broth (CEB) and Preston broth (PB). METHODS AND RESULTS: Pure cultures of target and competitor organisms, and naturally-contaminated food samples, were used to establish the performance of these media. In pure culture the PB supported the growth of the greatest number of strains of Campylobacter spp. but failed to inhibit some competitor organisms. The CEB showed the opposite result, inhibiting all 15 competitor organisms used but failing to support the growth of five Campylobacter strains. By comparison, BB showed the best compromise between inhibition of competitors and growth of Campylobacter. CONCLUSIONS: Plates inoculated with BB and CEB food enrichments resulted in more Campylobacter growth than those inoculated with PB, which supported significantly less typical growth (P < or = 0.001). The most common competitor organism isolated from PB was Escherichia coli, and Pseudomonas spp. were frequently isolated from BB and CEB. Both BB and CEB were better than PB for the isolation of Campylobacter from naturally-contaminated foods, although BB yielded more confirmed Campylobacter growth than CEB. SIGNIFICANCE AND IMPACT OF THE STUDY: This study highlighted differences in performance of media used to isolate Campylobacter spp. from foods.

Campylobacter↗