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Biomedical subjects

S Notermans

Publications and source records attributed to S Notermans.

At least 55 records · Page 3Linked to original sources
PubMed1990

The use of DNA probes for confirming enterotoxin production by Staphylococcus aureus and micrococci.

DNA-DNA colony hybridization was employed to evaluate the results obtained by different immunological methods for detection of staphylococcal enterotoxin. Staphylococcus aureus strains tested for staphylococcal enterotoxin production by immuno-assays and micrococci not previously tested for staphylococcal enterotoxin production were examined for presence of the genes encoding for staphylococcal enterotoxin A, B, C and E by using three corresponding DNA probes. The staphylococcal enterotoxin A probe also detected staphylococcal enterotoxin E gene because of 100% homology. The optimal sensitivity plate method showed the best accordance between the immuno-assay and the hybridization reactions. The enzyme-linked immunosorbent assay detected 12.5 to 17% staphylococcal enterotoxin producers without hybridization reactions. The microslide gel double diffusion test and the reversed passive latex agglutination test showed rather poor accordance with the hybridization reactions. All 17 strains of different micrococci investigated were negative in hybridization with all three DNA probes.

Base Sequence↗
PubMed1990

Evaluation and interpretation of data obtained with immunoassays and DNA-DNA hybridization techniques.

During the last decade several new analytical techniques have been developed for testing food products and clinical samples. One technique uses sensitive immunoassays such as enzyme-linked immunosorbent assay (ELISA) and latex agglutination. The most important step in developing sensitive immunoassays is the evaluation of the assay for specificity, cross-reactivity and sensitivity. False-negative results can easily be detected by adding known quantities of antigen to the sample. The most appropriate way to detect false-positive results is the specific inhibition of the immunological reaction by addition to the test-sample of either synthetic epitopes or anti-idiotype antibodies. The progress in recombinant DNA techniques now offers opportunities for application as analytical tools in food and clinical microbiology. Methods are being developed to detect microorganisms by their nucleic acid sequence using the so-called hybridization procedure. With this technique, labelled DNA fragments (probes) are hybridized with a complementary base sequence present in the microorganism. Foodborne pathogens can be detected by using a probe with a complementary base sequence which codes for toxin production. DNA-DNA hybridization techniques may replace the traditional cultural techniques for assaying pathogenic micro-organisms. However, more experience with these techniques is needed before further evaluation can be given.

Antigens, Bacterial↗
PubMed1990

Survival of pathogenic microorganisms in an egg-nog-like product containing 7% ethanol.

A liquor consisting of whole egg, saccharose (25% w/v) and ethanol (7.0% w/v) was artificially contaminated with Salmonella enteritidis, S. typhimurium, Staphylococcus aureus (three different strains), Bacillus cereus and Listeria monocytogenes. After 3 weeks of incubation at 22 degrees C the numbers of Salmonella, S. aureus and L. monocytogenes decreased more than 3 log10 units. Under such conditions, however, the total number of microorganisms increased 3 log10 units. At 4 degrees C the decrease of pathogenic microorganisms was much slower and a decrease of 3 log10 units was observed only after 7 weeks of incubation. Egg-nog, without ethanol, incubated at 22 degrees C allowed growth of Salmonella and S. aureus, while the numbers of B. cereus spores remained unchanged. Vegetative cells of B. cereus as well as L. monocytogenes decreased in numbers. However, after prolonged incubation the numbers of L. monocytogenes increased significantly.

Alcoholic Beverages↗
PubMed1990

Aerolysin of Aeromonas sobria: evidence for formation of ion-permeable channels and comparison with alpha-toxin of Staphylococcus aureus.

Aerolysin from Aeromonas sobria AB3 was isolated and purified. The pure toxin formed sodium dodecyl sulfate-insoluble oligomers in a lipidic environment. The addition of aerolysin to the aqueous phase bathing lipid bilayer membranes resulted in the formation of ion-permeable channels which had a single-channel conductance of about 70 pS in 0.1 M KCl. This defines the toxin as a channel-forming component similar to other toxins but without any indication for an association-dissociation reaction, since the channels had a long lifetime at low voltages. At voltages higher than 50 mV, the aerolysin channel switched into a closed state with a low residual conductance. The single-channel conductance was a linear function of the total aqueous conductance, which suggested that the toxin oligomers formed aqueous channels with an estimated minimal diameter of about 0.7 nm. The aerolysin pores were found to be slightly anion selective. The pore-forming properties of aerolysin were compared with those of alpha-toxin of Staphylococcus aureus. Both aerolysin and alpha-toxin share secondary structure features, must oligomerize to form pores in lipid bilayer membranes, and form channels with similar properties.

Aeromonas↗
PubMed1990

Synthetic DNA probes for detection of enterotoxigenic Clostridium perfringens strains isolated from outbreaks of food poisoning.

Four synthetic oligonucleotides encoding different parts of the Clostridium perfringens enterotoxin gene were used to test the enterotoxigenicity of C. perfringens strains isolated from confirmed outbreaks of food poisoning. Of the 245 strains isolated from food and feces originating from 186 separate outbreaks, 145 (59%) gave hybridization reactions with each of the four DNA probes used, while 104 strains did not hybridize with any of the probes. There was no correlation between serotype and the presence of the enterotoxin gene, although the C. perfringens enterotoxin gene was rarely detected among nontypable strains (17%). Results show that DNA hybridization is a suitable method for the identification of C. perfringens strains which have the potential to produce enterotoxin.

Base Sequence↗
PubMed1989

Cloning and sequencing of the Clostridium perfringens enterotoxin gene.

Several gene banks of Clostridium perfringens in E. coli were constructed. Using a mixture of synthetic 29-mer DNA probes clones were selected containing inserts from the C. perfringens gene coding for the enterotoxin. This has allowed sequencing of the complete gene and its flanking regions. The decuded amino acid sequence (320 a.a.) was found to differ at several sites from the sequence published previously by others. Two 40-mer DNA-probes were used to detect the toxin gene in C. perfringens strains isolated from the faeces of different non-symptomatic animals. Only 6% of the strains were found to possess the gene.

Base Sequence↗
PubMed1989

Carbon assimilation and extracellular antigens of some yeast-like fungi.

Many yeast-like fungi assimilated n-hexadecane, butylamine and putrescine as sole carbon sources. Methanol was not assimilated. This points to a physiological similarity to endomycetous, hydrocarbon-utilizing yeasts. Stephanoascus ciferrii assimilated uric acid, adenine and allantoin as sole source of carbon and nitrogen. All strains of Geotrichum candidum and many other yeast-like fungi assimilated acetoin and butan-2,3-diol. Assimilation tests for adenine, uric acid, allantoin, acetoin and butan-2,3-diol were found to be suitable for taxonomic purposes. Extracellular antigens immunologically related to those produced by Geotrichum candidum were detected in the cell-free culture liquids of several yeast-like fungi. The extracellular antigen excreted by Stephanoascus ciferrii was species-specific.

Alkanes↗
PubMed1989

DOT-enzyme linked immunosorbent assay for detection of Clostridium perfringens type A enterotoxin.

A procedure, which we have termed DOT-ELISA, to detect Clostridium perfringens type A enterotoxin on nitrocellulose paper is described. Seventy eight preparations from 39 cultures of C. perfringens type A were tested simultaneously by this and by Plate-ELISA methods. The results were comparable. DOT-ELISA detected as little as 0.02 micrograms of purified enterotoxin and 0.13 micrograms of enterotoxin in cell-free culture supernatant. As little as 0.02 micrograms purified enterotoxin mixed with human faeces could be detected specifically. The method is simple and does not require an ELISA reader.

Clostridium perfringens↗
PubMed1989

Detection of beta-galactofuranosidase production by Penicillium and Aspergillus species using 4-nitrophenyl beta-D-galactofuranoside.

An assay was developed for detecting beta-galactofuranosidase produced by Penicillium and Aspergillus spp. The substrate for the assay, 4-nitrophenyl beta-D-galactofuranoside, was synthesized from penta-O-acetyl-beta-D-galactofuranose and 4-nitrophenol by a tin chloride catalyzed reaction followed by O-deacetylation. Aspergillus spp. produced only small quantities of beta-galactofuranosidase during 30 d at 25 degrees C. Only the biverticillate Penicillium spp. (P. funiculosum, P. islandicum, P. rubrum and P. tardum) produced substantial beta-galactofuranosidase after 1-4 weeks at 25 degrees C. No extracellular antigens of these four Penicillium spp. could be detected in culture filtrates by the sandwich ELISA technique when antibodies to the extracellular beta-galactofuranoside-containing polysaccharide antigen of P. digitatum was used. Antigens to all other Penicillium and Aspergillus spp. were easily detected in their culture filtrates.

Antigens, Fungal↗
PubMed1989

Specific gene probe for detection of biotyped and serotyped Listeria strains.

A total of 284 strains of Listeria, including all known serovars and biovars together with Listeria grayi and Listeria murrayi, were biotyped and serotyped. Biotyping and serotyping could be done in 2 days. A gene probe encoding a delayed hypersensitivity factor (DTH) was used in the detection of pathogenic biotypes and serotypes of the tested strains. The gene was found in all 117 tested Listeria monocytogenes strains of serogroups 1/2a, 1/2b, 1/2c, 3a, 3b, 3c, 4c, 4d, 4e, 4ab, and 7. It was also present in Listeria ivanovii. Of 78 L. monocytogenes strains of serogroup 4b, 77 strains contained the gene, whereas it was absent in all 10 tested L. monocytogenes strains of serogroup 4a. Furthermore, the gene was absent in Listeria seeligeri, L. grayi, L. murrayi, and L. innocua of serogroups 3c, 4b, and 6a and in L. welshimeri of serogroups 1/2b, 3b, 6a, and 6b. Since L. monocytogenes and L. ivanovii are the only two biotypes of the genus Listeria considered pathogens, the data obtained indicate that the DNA probe tested may be a useful tool in the detection of virulent Listeria isolates in clinical, environmental, and food samples.

Bacterial Typing Techniques↗
PubMed1989

The use of the Listeria monocytogenes DTH gene for the detection of pathogenic biovars in food.

A gene probe encoding a Listeria monocytogenes delayed type hypersensitivity factor (DTH) was used for the detection of pathogenic biovars/serovars of the genus Listeria isolated from soft cheese. A total of 187 strains, isolated by plating techniques, were screened. The probe reacted with all isolated serovars of L. monocytogenes (except one 4b strain) and did not react with any of the Listeria innocua strains. Using the mouse bio-assay, as described by Kaufmann, a significant correlation was found between probe reaction and pathogenicity.

Animals↗
PubMed1988

Effect of environmental conditions during soya-bean fermentation on the growth of Staphylococcus aureus and production and thermal stability of enterotoxins A and B.

During tempe manufacture, Staphylococcus aureus was able to survive in newly started soya-bean soaks (final pH 4.7), whereas it died during soaks with accelerated souring (final pH 4.0). No S. aureus were detected after subsequent heat treatment of soaked beans. S. aureus strain S6 could produce enterotoxins A and B if inoculated on cooked soya-beans. Its growth and enterotoxin production were not influenced by inoculation rate nor by the presence of actively growing Rhizopus oligosporus, the fungus responsible for tempe formation. Enterotoxin levels were highest after 48 h fermentation. Presence of lactobacilli (L. brevis or L. plantarum) during the tempe fermentation did not influence staphylococcal growth, but enterotoxin levels were reduced. Reduced oxygen pressure did not affect staphylococcal growth, but resulted in lower enterotoxin levels after 48 h incubation. The thermal stability of enterotoxin A in tempe was significantly lower than in Brain Heart Infusion broth of comparable pH. Heating of enterotoxin-containing tempe mash reduced enterotoxin A by 99.7% as measured with ELISA and animal feeding methods.

Animals↗
PubMed1988

The effect of growth conditions on production and excretion of extracellular antigens by three ascomycetous yeasts.

Ascomycetous yeasts produce extracellular antigens that are almost specific for the species. The antigen production by Hansenula wickerhamii and Stephanoascus ciferrii was independent of the carbon source and was proportional to the final cell density of the cultures. The same was true of chemostat cultures of Stephanoascus ciferrii, irrespective of the dilution rate and whether glucose or ammonia was the limiting nutrient. In cultures of Saccharomyces cerevisiae, however, antigen excretion mainly took place in the late exponential growth phase. Large amounts of antigen were extracted from the cell wall of Saccharomyces cerevisiae. A small amount was detected in the cytoplasm.

Ammonia↗
PubMed1988

(1----5)-linked beta-D-galactofuranosides are immunodominant in extracellular polysaccharides of Penicillium and Aspergillus species.

Aspergillus and Penicillium species produce extracellular polysaccharides which are immunologically active. Methyl beta-D-galactofuranoside interferes with the reaction between the polysaccharide antigens and the antibodies raised in rabbits. Of the different interlinked dimers of beta-D-galactofuranosides (1----2; 1----3; 1----5; 1----6) the (1----5) interlinked beta-D-galactofuranoside gave the highest inhibition. An increasing inhibitory effect of di-, tri-, tetra-, penta-, hexa-, and heptamer of (1----5) interlinked beta-D-galactofuranosides was observed. It was noticed that the penta-, hexa- and heptamer of (1----5) interlinked beta-D-galactofuranosides were able to link antibodies raised against the extracellular polysaccharides produced by Penicillium species. The tetramer molecule was able to neutralize the binding of antibodies, which are naturally present in human sera, to the polysaccharides produced by Penicillium and Aspergillus species.

Antibodies, Fungal↗
PubMed1988

Production of enterotoxins and thermonuclease by Staphylococcus aureus in cooked egg-noodles.

Production of enterotoxin A (SEA), enterotoxin C (SEC), and thermonuclease (TNase) by Staphylococcus aureus was determined during growth in cooked egg-noodles at different temperatures (15-37 degrees C). Both SEA and SEC and TNase were detected when greater than or equal to 4.0 x 10(7) colony forming units (cfu)/g were present. The contents of SEA, SEC, and TNase in egg-noodles mainly increased at the end of the exponential growth phase. In contrast with SEA and SEC the production of TNase always continued till the end of each experiment. Recovery rates of SEA and TNase in cooked noodles were dependent on their amounts. High amounts (64 ng SEA/g; 1 unit TNase/g) were recovered at a rate of 93% (SEA) and 54% (TNase) respectively, whereas low concentrations (1 ng SEA/g; 0.004 units TNase/g) were recovered at a rate of only 45% (SEA) and 1.1% (TNase). TNase usually is produced at all conditions which allow growth of S. aureus. Evidence of TNase was proposed for screening for staphylococcal enterotoxins (SE) in foods. But sometimes foods contain no TNase but SE. For this reason the ELISA-test which is simple and sensitive should be used for determination of SE-production in foods.

Animals↗
PubMed1988

Human serum antibodies to extracellular polysaccharides (EPS) of moulds.

The presence of antibodies to extracellular polysaccharides (EPS) of moulds in sera of healthy subjects (N = 125) was determined. Antibodies against the EPS of Penicillium digitatum, Mucor racemosus, Cladosporium cladosporioides, Fusarium moniliforme and Botrytis tulipae were found in relatively high amounts in all sera. No effect of age on antibodies present could be demonstrated. Antibodies against each of the EPS tested were only neutralized by the homologous EPS and by EPS of moulds belonging to the same genus or a taxonomically closely related genus. Antibodies against the EPS of P. digitatum were inhibited by methyl-beta-D-galactofuranoside, indicating that the galactofuranose part of this EPS is immunodominant.

Antibodies, Fungal↗
PubMed1988

Synthetic enterotoxin B DNA probes for detection of enterotoxigenic Staphylococcus aureus strains.

DNA-DNA colony hybridization experiments with three different synthetic probes were carried out with 210 strains of Staphylococcus aureus. The synthetic probes encoded the amino acids 15 to 29 (probe 1), 179 to 192 (probe 2), and 207 to 219 (probe 3) of staphylococcal enterotoxin B (SEB). The amino acid sequences of these parts of SEB are identical to those of SEC1. All 21 SEB-producing strains tested reacted with each of the three probes. Of the 69 SEC-producing strains, 21 reacted with probe 1, none reacted with probe 2, and all 69 reacted with probe 3. With other strains no hybridization signals were obtained. The results presented here show that with a single synthetic DNA probe (probe 3) both SEB- and SEC-producing strains are detectable.

Amino Acid Sequence↗