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PubMed2000

Common occurrence of enterotoxin genes and enterotoxicity in Bacillus thuringiensis.

Seventy-four strains of Bacillus thuringiensis thuringiensis representing 24 serovars were examined for the presence of three enterotoxin genes/operons; the non-haemolytic enterotoxin Nhe, the haemolytic enterotoxin hbl and the Bacillus cereus toxin bceT using polymerase chain reaction. The nheBC genes were found in all strains examined, the hblCD genes in 65 of the 74 strains and bceT in 63 strains. There was little consistency of the distribution of enterotoxin loci among strains of the same serovar in serovars that were well represented in our collection. Culture supernatants from all but one strain inhibited protein synthesis in Vero cells, generally with a toxicity equivalent to that seen in strains of B. cereus isolated from incidents of food poisoning. Microbiological Societies.

Animals↗

PubMed1980

Enterotoxin production by Yersinia enterocolitica and Yersinia enterocolitica-like microbes at 22 degrees C and 37 degrees C.

A total of 32 strains of Yersinia enterocolitica and Y. enterocolitica-like microbes were examined for their ability to produce E. coli ST-like enterotoxin when grown at 22 degrees C and 37 degrees C, using the infant mouse assay. Enterotoxin production was indicated for 19 (59%) of the 32 strains examined. Nine of ten sucrose non-fermenting strains belonging to O-serogroup 28 produced enterotoxin at both 22 degrees C and at 37 degrees C. Eight of these strains were obtained from the intestinal contents of apparently healthy small mammals or from water samples at three different localities in Norway. One O-serogroup 28 culture was a reference strain received from Institut Pasteur, Paris. With the exception of O-serogroup 28, enterotoxins were detected only after incubation at 22 degrees C. The infant mouse assay was positive for all the four clinical isolates belonging to O-serogroup 3/biotype 4. Six of 13 different reference strains were positive in this assay.

Enterotoxins↗

PubMed1982

Demonstration of Escherichia coli heat-labile enterotoxin using bacterial cell sonicates.

Agar-plate colonies of Escherichia coli were suspended in 0.5 ml distilled water and sonicated for 15 s. The sonicate was tested for E. coli heat-labile enterotoxin by an enzyme-linked immunosorbent assay (ELISA). Sonication of enterotoxin-producing E. coli cells gave detectable toxin concentrations, which correlated well with the results obtained using culture broth supernatants for toxin detection in the ELISA. By using sonicates of isolated bacterial colonies from primary isolation agar plates, the subcultivation on agar plates or in culture broth tubes can be omitted. This may reduce the possibility of losing the plasmids coding for enterotoxin production. The time needed for analysis of suspected toxin producing E. coli strains will be reduced accordingly. Suspensions with bacterial counts of 10(6) per ml or more of E. coli, gave detectable levels of heat-labile enterotoxin in the sonicates.

Bacterial Toxins↗

PubMed1994

Tetanus toxin and Clostridium perfringens enterotoxin as tools for the study of exocytosis.

The role of calmodulin in exocytotic secretion was studied using digitonin-permeabilized bovine adrenal chromaffin cells to examine the effect of calmodulin directly introduced into the cells and using tetanus toxin as a specific inhibitor of exocytotic secretion. Addition of calmodulin to the permeabilized cells increased Ca(2+)-dependent norepinephrine release in a dose-dependent manner. The enhancement of release by calmodulin was specific to calmodulin: bovine serum albumin, actin, and caldesmon had no such effect. Enhancement of release by calmodulin occurred at Ca2+ concentrations of more than 10(-6) M and increased with an increase of Mg2+ concentration. The release of norepinephrine enhanced by calmodulin was inhibited by tetanus toxin. These results indicate directly that calmodulin plays an important role in exocytotic secretion from chromaffin cells. Exocytosis is known to occur by fusion of plasma membrane with limiting membranes of secretory vesicles following an increase in intracellular Ca2+. We used the enterotoxin of Clostridium perfringens type A as a specific tool to modify plasma membrane permeability to induce calcium influx. Multigranular exocytosis was recognized electron-microscopically in addition to the single-granular exocytosis in rat anterior pituitary cells and pancreatic acinar cells treated with the enterotoxin in the presence of extracellular Ca2+. The treatment with the enterotoxin did not induce any drastic change in the fine membrane structures of both types of cells. The enterotoxin-treated anterior pituitary cells and pancreatic acinar cells should provide a useful system for studying the molecular mechanism of fusion of membranes in exocytosis.

Adrenal Medulla↗

PubMed1991

Excretion of enterotoxin-producing Clostridium perfringens in feces by patients during and after diarrhea.

The excretion in the feces of Clostridium perfringens producing enterotoxin by 48 patients in 3 cases of food poisoning was studied during the illness and 1 and 3 months after the onset. Patients in the first outbreak excreted such strains mostly in the form of spores. In the second outbreak, spores and viable count cells were excreted in nearly equal numbers, and about 50% of the spores were enterotoxigenic. In the third outbreak, the strains were detected both as spores and as viable count cells during the illness. In all three groups, most fecal samples contained at least 10(3) spores per gram. About 1 month after the onset of the illness, (long after recovery from symptoms), 12 colonies producing enterotoxin were detected from five of the 22 samples of feces obtained from subjects in the three groups. There were few C. perfringens organisms, mostly spores, in the feces. Enterotoxin was not detected in the feces. About 3 months after onset, colonies producing enterotoxin could not be detected from feces of 11 of the subjects in the first group. We conclude that persons affected by C. perfringens food poisoning might contaminate food for at least 1 month after the onset.

Clostridium perfringens↗

PubMed1993

[Methicillin resistance, production of toxic shock syndrome toxin-1 and types of enterotoxin, protease and coagulase at vaginal isolates of Staphylococcus aureus].

The vaginal colonization with Staphylococcus aureus, including strains that have methicillin resistance and production of toxic shock syndrome toxin-1 (TSST-1), enterotoxins and protease was studied in 308 women at the time of delivery. Thirty-six of these women were colonized with S. aureus in the vagina. All of the isolates were methicillin sensitive S. aureus (MSSA), except one women who had both methicillin resistant S. aureus (MRSA) and MSSA. The strains, included MRSA, did not elaborate the TSST-1 and produced protease. The distribution of protease pattern (types) observed by MSSA strains on standard methods caseinate agar plates was type A, 1 strain; type B, 15 strains; type C, 6 strains; type D, 14 strains. Sixteen of the 36 strains produced non of the enterotoxins and 20 strains produced enterotoxins and the type distribution was enterotoxin type A, 6 strains; type B, 10 strains; type C, 1 strain; A and B, 1 strain; A, B and C, 2 strains. These results provide the possibility of pathogenic S. aureus colonized in vagina transmit to neonates at the time of delivery.

Adolescent↗

PubMed1983

Synthesis and secretion of the plasmid-coded heat-labile enterotoxin of Escherichia coli in Vibrio cholerae.

Both cholera toxin and heat-labile enterotoxin were made and secreted into culture supernatants by Vibrio cholerae containing the enterotoxin plasmid pCG86. Several regulatory mutations in V. cholerae that increased or decreased the synthesis of cholera toxin did not affect production of heat-labile enterotoxin. In contrast, a mutation in V. cholerae that interfered with the secretion of cholera toxin also decreased the secretion of heat-labile enterotoxin, indicating that they are processed by a common secretory pathway. Vibrio cholerae should be useful as a model system for analyzing the secretion of true extracellular proteins by Gram-negative bacteria.

Bacterial Toxins↗

PubMed1972

Effect of secondary metabolites on the organisms producing them: effect of nisin on Streptococcus lactis and enterotoxin B on Staphylococcus aureus.

The effect of secondary metabolites added to cultures of the organisms producing them was investigated. Nisin was added to growing cultures of a nisin-producing strain of Streptococcus lactis (354/07) and enterotoxin B to strains of Staphylococcus aureus (S6 and 243) producing enterotoxin B. One quarter (12 mug/ml) of the amount of nisin formed by the culture of S. lactis inhibited lag-phase cells and lysed log-phase cells. The same amount of nisin added before inoculation or at a time when nisin synthesis had started (in late log phase), caused only transient delay in growth. Inhibition of growth of the two enterotoxin B-producing strains of S. aureus could not be demonstrated at any stage of their growth cycle with as much as 1 mg of enterotoxin B per ml of medium.

Anti-Bacterial Agents↗

PubMed1976

Recovery of staphylococcal enterotoxin from foods by affinity chromatography.

Extraction, concentration, and serological detection of staphylococcal enterotoxins from foods are laborious and time consuming. By exposing food extracts to an insoluble matrix tagged with specific anti-enterotoxin B, we have been able to recover the toxin from foods in a sensitive and rapid way. After mixing the reagents for 2 h at room temperature, immunoglobulin G antibodies were attached to CNBr-activated Sepharose 4B at pH 8.5 (0.1 M carbonate buffer with 0.5 M NaCl). Sepharose-antibody complex (1 ml) specifically recovered 0.1 to 30 mug of enterotoxin B from 400 ml of food extract (100 g of food) after mixing for 2 h at 4 C. The Sepharose-antibody-toxin complex was washed with 0.02 M phosphate-buffered saline at pH 7.2, and the toxin was dissociated by 2 to 4 ml of 0.2 M HCl-glycine plus 0.5 M NaCl buffer at pH 2.8. The recovered enterotoxin was free of interfering food components and could be detected serologically. Work to couple antibodies A, B, C, D, and E to Sepharose to recover all five toxins in one step is under study.

Antigen-Antibody Complex↗

PubMed1976

Biochemistry of Vibrio cholerae virulence: purification of cholera enterotoxin by preparative disc electrophoresis.

Procedures for cholera enterotoxin purification previously developed in this labarotory were not applicable to large-scale purification, and these methods resulted in low yields of pure toxin. An efficient scheme has been developed whereby pure cholera enterotoxin can be obtained from 6 to 8 liters of culture supernatant fluid. This method consists of concentration by membrane ultrafiltration followed by gel filtration and cation-exchange chromatography. Pure cholera enterotoxin of high biological potency was obtained after a final step of preparative acrylamide gel electrophoresis. The degree of purity of the toxin-antigen as well as its biological activity were determined at various setps of purification. This alternate technique for purification is offered because of the widespread interest in cholera enterotoxin as a specific stimulator of adenyl cyclase.

Animals↗

PubMed1979

Magnesium and iron addition to casein hydrolysate medium for production of staphylococcal enterotoxins A, B, and C.

From comparisons of 4% N-Z Amine NAK made with distilled water, naturally hard water, and synthetic salt solutions, it appeared that magnesium and, to a lesser extent, iron were limiting factors in the production of staphylococcal enterotoxins B and C but not A. Maximum enterotoxin production with NAK medium was achieved by the addition of 5 mg of Mg2/ per liter (for a total of 9 mg of Mg2+ per liter) and 0.5 mg of Fe2+ per liter. Higher levels of magnesium were not inhibitory. Supplementing NAK with commonly used complex components, which added Mg2+ above the 9-mg/liter level, did not result in maximum yields of enterotoxin. Variability in the ability of different lots of NAK to support enterotoxin production may be minimized by supplementing NAK medium with magnesium and iron.

Caseins↗

PubMed1980

Identification of a chromosomal determinant of enterotoxin A production in Staphylococcus aureus.

Chromosomal mapping of the determinants for enterotoxin A and enterotoxin B production in three strains of Staphylococcus aureus was attempted by using conventional transformation procedures and a series of multiply marked derivatives of NCTC 8325 as recipients. A gene governing enterotixin A production (entA+) in strain S-6 was located on the chromosome between the pur-110 and ilv-129 markers, very close to a determinant of alpha-hemolysin production, hla+. The entA+ gene of strain FRI-196E was shown not to be located at the same position; its location could not be determined. The entB+ genes of strains S-6 and C243 were not located within the known linkage groups examined. Recombinants were screened for enterotoxin production by a new procedure that combined characteristics of immune serum plate and optimal sensitivity plate procedures. The strains and methods used in this study of enterotoxin determinants should prove useful in genetic studies to locate other chromosomal determinants of S. aureus whose phenotypes are difficult to score or select for.

Chromosome Mapping↗

PubMed1983

Medium-dependent production of extracellular enterotoxins by non-O-1 Vibrio cholerae, Vibrio mimicus, and Vibrio fluvialis.

Fluid accumulation at 4 h in the intestines of suckling mice enabled us to distinguish non-O-1 Vibrio cholerae, V. mimicus, and V. fluvialis clinical isolates from environmental isolates. Enterotoxin production was culture medium dependent. Filtrates of cultures grown in tryptic soy broth without glucose but with added 0.5% NaCl did not exhibit marked enterotoxin activity in the assay. Culture filtrates of all clinical strains grown in brain heart infusion broth supplemented with 0.5% NaCl induced large amounts of fluid accumulation in mouse intestines. However, most environmental strains grown in brain heart infusion broth amended as described above were unable to induce fluid accumulation. The enterotoxin present in culture filtrates lost activity at 56 degrees C and appeared to be distinct from previously described virulence factors, including the well-described cholera toxin. The new enterotoxin could represent an important virulence mechanism common to all three species.

Culture Media↗

PubMed1985

Synthetic oligodeoxyribonucleotide probes for detecting heat-stable enterotoxin-producing Escherichia coli by DNA colony hybridization.

DNA colony hybridization was used to identify and enumerate enterotoxigenic Escherichia coli strains in foods. The cells were identified and enumerated by using synthetic polynucleotide probes for the heat-stable enterotoxin genes. These 22-base oligonucleotides, made from known nucleotide sequences of the genes for the heat-stable enterotoxins of human and porcine strains of E. coli, contain two mismatches between the two heat-stable enterotoxins. Colonies were replicated from agar medium onto paper filters and lysed with alkali followed by steam; probes were end labeled. After overnight hybridization at 40 degrees C and washing at 50 degrees C, autoradiograms were exposed at -70 degrees C. Results were consistent with suckling-mouse tests for heat-stable enterotoxins. A stronger signal was obtained on paper filters than on nitrocellulose filters. Enterotoxigenic E. coli cells were detected when mixed with a 1,000-fold excess of nonenterotoxigenic E. coli cells. This procedure appears to be more acceptable for routine testing than the use of cloned DNA fragments, labeling by nick translation, and lysing colonies on nitrocellulose filters.

Bacterial Toxins↗

PubMed1988

Novel method for purification of staphylococcal enterotoxin A.

A novel single-step procedure for the purification of staphylococcal enterotoxin A (SEA), namely, dye ligand affinity chromatography with the triazine dye Red A, was developed. SEA purified by this method produced a single band when subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The yield from 5 liters of culture supernatant was 0.113 g, corresponding to an overall yield of 55%. In some instances, purification of SEA from culture supernatants by dye ligand affinity chromatography produced two enterotoxin peaks that could be eluted from the column with 300 and 500 mM phosphate buffer (pH 6.8). Enterotoxin from these peaks produced a single band when subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis, but multiple bands were observed on isoelectric focusing gels. This method of purification represents a significant improvement in time, yields, and purity of enterotoxin over previously published purification methods.

Chromatography, Affinity↗

PubMed1994

Identification and analysis of the antigens detected by two commercial Bacillus cereus diarrheal enterotoxin immunoassay kits.

The usefulness of two commercial immunoassays for the detection of diarrheal enterotoxin of Bacillus cereus is unclear because the identity of the enterotoxin(s) has not been proven and the kits detect different proteins. We found that the Bacillus cereus Enterotoxin-Reversed Passive Latex Agglutination kit (Oxoid) detects the L2 component from hemolysin BL, and the Bacillus Diarrhoeal Enterotoxin Visual Immunoassay (Tecra) detects two apparently nontoxic proteins.

Agglutination Tests↗

PubMed1968

Heat inactivation of enterotoxin A from Staphylococcus aureus in veronal buffer.

Serological tests were used to determine the slope of the thermal inactivation curve of crude enterotoxin A in Veronal buffer (pH 7.2), and the resulting z value was 27.8 C. (50 F). Serological assays also showed that the heat inactivation at each time-temperature depended on the original concentration of enterotoxin A. The usefulness of the Oudin tube serological test for determining end points of inactivation of naturally produced enterotoxin A (not concentrated) is discussed. We concluded that this test cannot be used to determine end points of heat inactivation for enterotoxin A in the minute quantities naturally produced in foods.

Buffers↗

PubMed1971

Effect of toxin concentration on the heat inactivation of staphylococcal enterotoxin A in beef bouillon and in phosphate buffer.

The slope of the thermal inactivation curve of enterotoxin A in beef bouillon (initial pH 6.2) was found to be approximately 27.8 C (50 F) with three different concentrations of toxin. Inactivation by heat was dependent on the concentration of enterotoxin A heated. Enterotoxin A was inactivated by less heat in a pH 7.2 phosphate buffer than in beef bouillon as detected by serology. Results indicate that natural (usually low) levels of toxin rather than concentrated enterotoxin A should be used in heat inactivation studies.

Animals↗