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PubMed1989

Salmonella mbandaka isolated in Italy. 1979-1986.

A total of 350 strains of Salmonella mbandaka were isolated in Italy during the period 1979 to 1986. S. mbandaka was a rare serotype in Italy. It was first isolated from water in 1979. Since that year the number of isolates has increased: 1980 (3), 1981 (21), 1982 (21), 1983 (24), 1984 (54), 1985 (108), 1986 (118). 67.1% of the strains were isolated from humans, 14.6% from food, 15.1% from water and 2.9% from animals. Frozen eggs and egg-based products were the most frequently contaminated foods. Of the forty-six strains tested for drug resistance, two were multiresistant to gentamicin, nalidixic acid and nitrofurantoin and to chloramphenicol, kanamycin, tetracycline and tobramycin, respectively.

Animals↗
PubMed2001

Listeria monocytogenes adheres to many materials found in food-processing environments.

AIMS: To investigate the adhesion of Listeria monocytogenes 10403S to 17 different, food-use approved materials representing metals, rubbers and polymers. METHODS AND RESULTS: Adhesion assays were conducted by placing 'coupons' of the materials in planktonic cultures at 30 degrees C, and then immediately withdrawing them ('short contact') or leaving them submerged in the cultures for 2 h. Adherent cells were recovered by sonication. In the short contact experiments, the logarithm of the mean viable counts ranged from 3.67 +/- 0.43 to 4.78 +/- 0.38. After 2 h contact time, the numbers of adherent cells had increased significantly for all materials with the exception of polypropylene. The highest count (6.33 +/- 0.31) recorded was for stainless steel 405. CONCLUSION: Adhesion to a wide range of materials was time-dependent and characterized by reversible and irreversible stages. SIGNIFICANCE AND IMPACT OF THE STUDY: Adhesion test protocols must account for cell carry-over and cells which are only weakly bound. Material selection may only have a limited role in reducing food contamination by listeria.

Bacterial Adhesion↗
PubMed1981

Enterotoxigenic Escherichia coli diarrhoea: acquired immunity and transmission in an endemic area.

Enterotoxigenic Escherichia coli (ETEC) are an important cause of diarrhoea in developing countries. Studies were made, in an endemic area of Bangladesh, of household contacts of patients with diarrhoea associated with E. coli producing heat-stable and heatlabile toxins (ST/LT) or heat-stable toxin (ST) only. It was found that 11% of contacts were infected in the 10-day study period, and that both the rate of infection and the proportion of infected persons with diarrhoea decreased with increasing age, suggesting the development of immunity. ETEC of the same serotype as that of the index patient were found in 9% of water sources used by index households, in a small number of food and drinking water specimens from the index homes, and in faeces from 3 healthy calves. The rate of infection of household members was highest in houses where there was contaminated food or water, which suggests that infection may take place in the home when contaminated water is brought in.

Bangladesh↗
PubMed1980

Alkali method for rapid recovery of Yersinia enterocolitica and Yersinia pseudotuberculosis from foods.

A new culture method employing a potassium hydroxide treatment was compared with the conventional cold enrichment method for efficacy in recovering Yersinia sp. from naturally and artificially contaminated food. The new method increased the yield of Yersinia sp. fourfold and the sensitivity 100-fold, shortened the incubation period, and appreciably decreased the growth of non-Yersinia bacteria from a variety of meats, shellfish, and vegetables.

Alkalies↗
PubMed1993

[Food borne outbreak of a Salmonella enteritidis epidemic in a large pharmaceutical industry].

In summer 1991 an outbreak of a Salmonella enteritidis epidemic involving about 600 cases of gastroenteritis occurred at one of the leading pharmaceutical companies in southwestern Germany. The main source was a cold fruit soup, in addition Salmonella were isolated from meat strips and a curd cheese which were used for a salad dressing. A total of 2300 contaminated food portions were served resulting in an attack rate of about 25%. The possible origin could have been an asymptomatic Salmonella-positive member of the kitchen personnel who was the only one who was involved with the preparation of all the incriminated foods. A further spread of the epidemic and especially the possible contamination of pharmaceuticals was avoided by the timely and adequate reaction of the company's occupational medical service. This case exemplifies how classical crisis management, "increased initiative on one's own for prevention of infections in all areas of food processing" (Steuer) and finally the cooperation of the company with different institutions of the public health authorities contribute to the control of such a catastrophic scenario.

Adult↗
PubMed1993

Prediction of pesticide behavior in soil by means of simple field tests.

A simple method is given for forecasting the reaction under different soil and site conditions of 106 pesticides with known binding strength by humus and clay in relation to pH and with known volatility and aerobic and anaerobic degradability. The method is based on easy-to-determine soil characteristics (texture, humus content, pH, groundwater table) and meteorological data (mean temperature, climatic water balance). It is possible to use this method to predict the environmental risk, especially the risk of contamination, and the groundwater pollution potential of a particular pesticide for a particular site in the field. In addition, recommendations for food contamination are given. This simple approach is suitable for use in on-site consultations. A reduction in pesticide input into near-surface groundwater can be expected when the recommendations derived from the model are applied. The use of this pragmatic model by farmers increases the awareness of the vulnerability of the groundwater recourse.

Adsorption↗
PubMed2004

Bioconcentration and redeposition of polychlorinated biphenyls by zebra mussels (Dreissena polymorpha) in the Hudson River.

The potential impact of zebra mussel infestation on the dynamics of polychlorinated biphenyls (PCBs) in the Hudson River was determined by investigating the biodeposition and bioconcentration of PCBs, using algal food contaminated with 2,5,2'- and 2,4,2',4'-chlorobiphenyls (CBPs) in the laboratory. Approximately 46-90% of the total food was ingested depending on the supply rate. The highest proportion of ingested congeners was found in biodeposits (64+/-11% for 2,5,2'-CBP, and 52+/-6% for 2,4,2',4'-CBP), followed by tissues (17+/-3% for 2,5,2'-CBP, and 23+/-5% for 2,4,2',4'-CBP), and the lowest in shells. The clearance rate decreased with increasing food concentration, but increased with dilution rate. On the other hand, ingestion rate (IR) increased with food concentration and dilution rate. IR also increased with food supply rate (food concentrationxdilution rate) following the same linear function whether the supply rate was varied through food concentration or dilution rate. Therefore, the dilution rate- or food concentration-dependent variation in IR was due to the change in the food supply rate. IR was independent of the kind of PCB congeners. The trend of bioaccumulation in mussel tissues from food ingestion was similar to that of IR; bioaccumulation increased linearly with food supply rate, whether the supply rate was varied through the dilution rate or the food concentration. The bioaccumulation of 2,4,2',4'-CBP was significantly higher than that of 2,5,2'-CBP (p<0.05). The bioaccumulation was linearly related to the IR or to the total amount of food ingested. Assimilation efficiency, PCB incorporated in the tissue per total ingested PCB, was higher for 2,4,2',4'-CBP than for 2,5,2'-CBP (p<0.05). The congener concentration in biodeposits increased with food supply rate. However, the concentration of 2,5,2'-CBP was significantly greater than that of 2,4,2',4'-CBP in a mirror image of bioaccumulation. These results indicate that zebra mussels may significantly alter PCB dynamics in the Hudson River through redeposition from the water column and through bioconcentration.

Animals↗
PubMed1988

Outbreaks of listeriosis/Listeria-contaminated foods.

Outbreaks of food-borne listeriosis in recent years have caused governmental regulatory and health agencies and the food industry to focus on the problem of food contamination by Listeria monocytogenes. A review is presented of the association of L. monocytogenes with human illness and its occurrence in foods and the environment.

Disease Outbreaks↗
PubMed2006

Deoxynivalenol and satratoxin G potentiate proinflammatory cytokine and macrophage inhibitory protein 2 induction by Listeria and Salmonella in the macrophage.

Health risks from microbial pathogens and toxins encountered in food and the environment continue to be of worldwide concern. The purpose of this research was to test the hypothesis that trichothecene mycotoxins amplify inflammatory responses to foodborne bacterial pathogens. We assessed the capacity of deoxynivalenol (DON) and satratoxin G (SG) to potentiate chemokine and proinflammatory cytokine production in RAW 264.7 murine macrophages induced by Listeria monocytogenes and Salmonella Typhimurium. When macrophage cultures were incubated with killed irradiated suspensions of the pathogens for 24 h, the minimum Listeria concentrations for induction of macrophage inhibitory protein 2 (MIP-2), interleukin-1beta (IL-beta), IL-6, and tumor necrosis factor alpha (TNF-alpha) were 0.01, 0.01, 1.0, and 1.0 microg/ml (P < 0.05) and the minimum Salmonella concentrations were 0.01, 0.01, 0.1, and 0.1 microg/ml, respectively (P < 0.05). Induction of all four mediators by both pathogens was potentiated by DON (at 100 and 250 ng/ml); observed responses were significantly higher than predicted additive responses (P < 0.05). SG (at 2 and 5 ng/ml) also significantly amplified induction of IL-1beta and TNF-alpha (P < 0.05) by both Listeria and Salmonella. These results indicate that DON encountered in Fusarium-contaminated food and SG from Stachybotrys-contaminated indoor environments could magnify innate inflammatory responses to foodborne bacterial pathogens.

Animals↗
PubMed1990

The neurotoxicology and pathology of organomercury, organolead, and organotin.

The toxicities of many metals, such as mercury and lead, are known to man since the dawn of civilization. Organic compounds of some heavy metals are known to have a particular toxic impact on the central nervous system. Organomercury, particularly alkyl-mercuric compounds (e.g. methylmercury), has a selective effect on the granule cells of the cerebellum, the nerve cells of the calcarine cortex, and the sensory neurons in the dorsal root ganglia. The well known Minamata Bay disease is the result of a massive epidemic episode of human exposure to alkylmercury contaminated food sources. Mental retardation and other developmental defects are also known to be a consequence of exposure to this toxic metal. Organic lead compounds have been employed as gasoline additives and in other industrial purposes. Unlike its inorganic counterpart, organolead compounds have a more prominent impact on the central nervous system. Pathological changes of the brain stem neurons have been described. Organotin compounds have been used in plastic industries and as agricultural chemicals. Both trimethyl and triethyl tin compounds are found to be extremely neurotoxic. Despite the similarity of their chemical structures, trimethyl and triethyl tins have a diversely different toxic property and effects. While triethyl tin is myelinotoxic, producing edematous and vacuolar changes in the central myelin, trimethyl tin is neurotoxic, producing prominent toxic changes in the neurons of the limbic system (hippocampus, entorhinal cortex, etc.). The factors which determine the specificity and selectivity of the neurotoxic impacts by various organometals are still unknown. In view that most of the organometals are still widely employed by many countries for industrial and for agricultural purposes, caution must be made for their proper handling and disposure to avoid undesirable exposures to workers and environmental contamination of water sources and food-chain for the common public. Since organometals are difficult to eliminate from the central nervous system, injuries usually lead to permanent neurological deficits, such tragedies are frequently long lasting and create not only a medical problem, but also a social economical problem for the society.

Animals↗
PubMed1982

Contamination of weaning foods and transmission of enterotoxigenic Escherichia coli diarrhoea in children in rural Bangladesh.

In longitudinal studies of infectious diseases and nutrition in Bangladesh, we determined the degree of bacterial contamination of traditional weaning foods and evaluated the role of these foods in the transmission of diarrhoeal diseases. 41% of samples of food items fed to weaning aged children contained Escherichia coli; these organisms were used as indicators of faecal contamination. Milk and foods prepared particularly for infants were more frequently and heavily contaminated with E. coli than was boiled rice, and E. coli levels were found to be related to the storage of cooked foods at high environmental temperatures. 50% of drinking water specimens also contained E. coli, but colony counts were approximately 10-fold lower than in food specimens. The proportion of a child's food samples that contained E. coli was significantly related to the child's annual incidence of diarrhoea associated with enterotoxigenic E. coli. This observation underscores the importance of seeking locally available foods that are hygienic as well as nutritious to supplement the diets of breastfeeding children in developing countries.

Bangladesh↗
PubMed1994

Evaluation of the Vitek Immunodiagnostic Assay System (VIDAS) for the detection of Salmonella in foods.

A Salmonella Assay using the Vitek Immunodiagnostic Assay System (VIDAS) was compared with a conventional cultural method (CCM) for the detection of salmonellas in 141 samples of artificially and naturally contaminated foods. There was an overall agreement of 92.9% between the methods. The productivity of the VIDAS Salmonella Assay (VSA) was not improved using an alternative enrichment protocol for the detection of Salmonella in 12 raw meat samples. The sensitivity and specificity of the VSA was assessed using pure cultures of salmonellas and non-salmonellas. The detection limit was 1.8 x 10(6) salmonellas ml-1 in M-broth and some Citrobacter freundii strains gave false-positive results. Using an immunomagnetic separation (IMS) technique and an abbreviated cultural enrichment, the VSA results could be obtained a day earlier than the standard VSA method.

Bacteriological Techniques↗
PubMed2003

Calicivirus infections in children.

PURPOSE OF REVIEW: Caliciviruses are a major cause of human illness, and are listed as category B pathogens according to the National Institute of Allergy and Infectious Diseases classification of pathogens important for biodefense. Caliciviruses are commonly encountered in contaminated food and water, and a large variety has been implicated as sources of infection during outbreak investigations. RECENT FINDINGS: New names for two of the four genera of the Caliciviridae were approved in 2002. They are Norovirus, for what were previously called Norwalk-like viruses or small, round-structured viruses, and Sapovirus, for what were previously called Sapporo-like viruses. Caliciviruses are highly diverse genetically and antigenically. This diversity complicates the design of diagnostic assays, yet can be used to discriminate contaminating and infecting strains during outbreak investigations. Of particular interest is the recent finding of naturally occurring recombinant Norovirus strains, all of which have been virulent and are widely dispersed and apparently ecologically indistinguishable from other calicivirus strains. This finding is considered in light of the evidence for recombination between caliciviruses and picornaviruses, and recombination as a more general phenomenon for virus evolution. SUMMARY: Continued investigations of calicivirus outbreaks are now focusing on the implicated sources of infection. While many foods and environmental waters have long been implicated as outbreak sources, the methods for detecting caliciviruses are being developed and refined. Recognition is now turning to unexpected sources of contamination, such as presumably clean foods and waters, including bottled water and minimally handled foods. Parallels between Norovirus and Salmonella ecology and epidemiology are noted, as a guide to understanding evolving new information about caliciviruses.

Caliciviridae↗
PubMed1985

Escherichia coli in retail processed food.

Four thousand two hundred and forty six samples of retail processed food were examined for the presence of Escherichia coli. Overall 12% of samples contained this organism, cakes and confectionery being more frequently contaminated (28%) than meat and meat based products (9%). Contamination was more frequent in the summer months than in the colder weather and 27% of the contaminated foods contained greater than 10(3) E. coli/g. E. coli from meat and meat based products were more commonly resistant to one or more antibiotics (14%) than were confectionery strains (1%). The significance of these findings in relation to the E. coli population of the human bowel is discussed.

Anti-Bacterial Agents↗
PubMed2005

Use of ramification amplification assay for detection of Escherichia coli O157:H7 and other E. coli Shiga toxin-producing strains.

Escherichia coli O157:H7 and other Shiga toxin-producing E. coli (STEC) strains are important human pathogens that are mainly transmitted through the food chain. These pathogens have a low infectious dose and may cause life-threatening illnesses. However, detection of this microorganism in contaminated food or a patient's stool specimens presents a diagnostic challenge because of the low copy number in the sample. Often, a more sensitive nucleic acid amplification method, such as PCR, is required for rapid detection of this microorganism. Ramification amplification (RAM) is a recently introduced isothermal DNA amplification technique that utilizes a circular probe for target detection and achieves exponential amplification through the mechanism of primer extension, strand displacement, and ramification. In this study, we synthesized a circular probe specific for the Shiga toxin 2 gene (stx(2)). Our results showed that as few as 10 copies of stx(2) could be detected, indicating that the RAM assay was as sensitive as conventional PCR. We further tested 33 isolates of E coli O157:H7, STEC, Shigella dysenteriae, and nonpathogenic E. coli by RAM assay. Results showed that all 27 STEC isolates containing the stx(2) gene were identified by RAM assay, while S. dysenteriae and nonpathogenic E. coli isolates were undetected. The RAM results were 100% in concordance with those of PCR. Because of its simplicity and isothermal amplification, the RAM assay could be a useful method for detecting STEC in food and human specimens.

Animals↗
PubMed2006

How terrestrial snails can be used in risk assessment of soils.

Among soil invertebrates, terrestrial snails are herbivorous and detritivorous organisms exposed to polluted soils by both digestive and cutaneous routes. Using laboratory-reared snails (Helix aspersa aspersa), we describe how the effects of contaminants on survival and growth of snails can be evaluated in laboratory bioassays. A national ring test was performed to assess the effect of Cd added to the soil or to the food. The ecotoxicity of sewage sludge also was evaluated. The present results demonstrate that toxicity depends on both the pollutants and the exposure route. Cadmium was sixfold more toxic for snails exposed via food contamination (median effective concentration [EC50], 68-139 microg/g) than via soil contamination (EC50, 534-877 microg/g), whereas the opposite occurred with the sewage sludge (EC50, 55% of sludge in the food and 10% of waste in the soil). A logistic relationship linked growth inhibition and internal Cd concentrations, which can reach 2,000 microg/g in the viscera of snails exposed to 626 microg/g in the food. No clear trend was found between Cu, Zn, Pb, Cr, and Ni concentrations in the sludge and in snail tissues. These data enabled the development of an international standard, which should enhance the use of terrestrial gastropods for both fundamental research and routine risk assessment in the terrestrial environment.

Animals↗
PubMed1992

Evaluation of the MPN, Anderson-Baird-Parker, Petrifilm E. coli and Fluorocult ECD method for enumeration of Escherichia coli in foods of animal origin.

Commercially available beta-D-glucuronidase (GUR) based methods, Petrifilm E. coli (PEC) and Fluorocult ECD (FECD), and ISO standard MPN and Anderson-Baird-Parker (ABP) procedures were evaluated for routine enumeration of E. coli in naturally contaminated foods of animal origin. The methods concerned were classifiable in a sequence of best qualities for: production, MPN > ABP = PEC = FECD; costs, FECD > ABP = PEC > MPN; time per measurement, ABP = PEC = FECD > MPN; practical use, PEC > FECD > ABP > MPN; detection at low contamination, MPN > ABP = PEC > FECD. The ABP and PEC method appeared useful for routine counting of E. coli in raw meat, poultry and meat products, whereas the MPN procedure turned out to be more sensitive, however, impractical and considerably more expensive. The FECD method was inexpensive although suitable for the enumeration of E. coli at higher contamination level (> 50 cfu/g). The indole and MUG indicators both applied to demonstrate E. coli with the ABP or FECD method proved to be equal in specificity.

Colony Count, Microbial↗