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PubMed1974

A consideration to immune doses of staphlococcal enterotoxin B to rabbits.

Immune doses of staphylococcal enterotoxin B to rabbits were studied by comparing the efficiency of various immunization schedules. It was experienced that even two subcutaneous injections each with such a small dose as 10 mug of enterotoxin B, the primary one with Freund's complete adjuvant and a booster one without adjuvant, could stimulate a rabbit to develop the antibody to a satisfactorily high titer determined by agar gel diffusion and passive hemagglutination.

Animals↗

PubMed1978

[Studies on staphylococcal enterotoxin B. 1. Quantitative assay by capillary tube single diffusion test (author's transl)].

A method for rapidly identifying and quantitating small amount of staphylococcal enterotoxin B was developed on capillary tube single diffusion test. The high sensitivity of method has the advantages to save antiserum and incubation period. Some factors such as concentration of antigen and antiserum, incubation temperature, buffer systems, and position of capillary tube all might affect the test accuracy. If all those affecting factors were concerned, the toxin would probably be standardized. The most accessible quantitative estimation was accomplished by means of (1) plotting a precipitation curve from the different concentrations of standardized staphylococcal enterotoxin B; (2) the sample to be test was diluted by serial two-fold method with the same buffer system; (3) select suitable 3--5 dilutions to perform capillary tube diffusion test, taking the values of precipitation bands as abcissa and sample dilutions as longitudinal axis, rendered the precipitation curve of sample exquisitely paralled to that of the standard; (4) calibrate the figure values of sample exactly on the precipitation curve, and reading the toxin content of specimen to be tested from standard curve.

Enterotoxins↗

PubMed1999

Analysis of mec regulator genes in clinical methicillin-resistant Staphylococcus aureus isolates according to the production of coagulase, types of enterotoxin, and toxic shock syndrome toxin-1.

The intrinsic resistance of methicillin-resistant Staphylococcus aureus (MRSA) is frequently explained by the production of an additional penicillin-binding protein (PBP), which is encoded by the mecA gene. The mec regulator genes, mecR1 and mecI, was identified in mecA-carrying Staphylococcus aureus N315. Between February and March, 1993, 179 clinical MRSA isolates were collected from institutions in Hiroshima prefecture. According to serological types of coagulase, enterotoxins, and toxic shock syndrome toxin-1 (TSST-1) productions, these strains were classified into 6 groups. In 53 strains chosen from all groups, mec regulatory gene distributions were divided into two groups; one with whole regulatory genes and another with the lacking region, including 3'-partial region of the mecR1 gene and mecI gene. This same deletion was detected across the different groups, suggesting that the deletion occurred at the ancestral strain before branching according to coagulase or enterotoxin productions. The strains with this lacking region showed a high-level of resistance to methicillin, while the strains with whole regulatory genes consisted of low and high levels of resistant strains. The highly resistant strains with whole regulatory genes were found to harbor a point mutation in the mecI gene. The basal levels of mecA gene transcription were elevated in the strains with the lacking region or the mecI point mutations. These data suggest that deletion or mutation of the mecI gene, the repressor on the mecA gene, might play an important role in methicillin resistance in clinical isolates of MRSA.

Bacterial Proteins↗

PubMed1999

Prevalence of enterotoxin gene (stn) among different serovars of Salmonella.

The prevalence of Salmonella enterotoxin (stn) gene among different Salmonella serovars by using polymerase chain reaction (PCR) and its status of expression on the Chinese hamster ovary (CHO) cells were investigated. All the 26 strains of Salmonella enterica such as serovars Typhimurium, Enteritidis, Dublin, Typhi, Newport, Weltevreden, Gallinarum, etc. investigated in this study were found to carry stn gene as examined by the PCR and gene probe. However, only a limited number of stn positive strains (34.6%) were found to express phenotypically the Salmonella enterotoxin (Stn) as tested by the CHO cell assay. The strains of S. bongori were found to be negative for Stn production both genotypically and phenotypically.

Animals↗

PubMed1999

Staphylococcal enterotoxin H displays unique MHC class II-binding properties.

Staphylococcal enterotoxin H (SEH) has been described as a superantigen by sequence homology with the SEA subfamily and briefly characterized for its in vivo activity. In this study, we demonstrate that SEH is a potent T cell mitogen and inducer of T cell cytotoxicity that possesses unique MHC class II-binding properties. The apparent affinity of SEH for MHC class II molecules is the highest affinity ever measured for a staphylococcal enterotoxin (Bmax1/2 approximately 0.5 nM for MHC class II expressed on Raji cells). An excess of SEA or SEAF47A, which has reduced binding to the MHC class II alpha-chain, is able to compete for binding of SEH to MHC class II, indicating an overlap in the binding sites at the MHC class II beta-chain. The binding of SEH to MHC class II is like SEA, SED, and SEE dependent on the presence of zinc ions. However, SEH, in contrast to SEA, binds to the alanine-substituted DR1 molecule, betaH81A, believed to have impaired zinc-bridging capacity. Furthermore, alanine substitution of residues D167, D203, and D208 in SEH decreases the affinity for MHC class II as well as its in vitro potency. Together, this indicates an MHC class II binding site on SEH with a different topology as compared with SEA. These unique binding properties will be beneficial for SEH to overcome MHC class II isotype variability and polymorphism as well as to allow an effective presentation on APCs also at low MHC class II surface expression.

Alanine↗

PubMed1999

[Isolation of toxigenic strains of Clostridium difficile and enterotoxin producing Bacteroides fragilis from fecal specimens of patients suspected of antibiotic associated diarrhoea].

Fifty faecal samples from patients suspected of AAD (antibiotic associated diarrhoea) were studied for Clostridium difficile and enterotoxin producing Bacteroides fragilis (ETBF). Using TCD (Becton-Dickinson) and C. difficile Toxin A test (Oxoid) in 34% of specimens the presence of toxin A was detected. From all specimens 25 C. difficile strains were isolated. All isolated strains produced toxin B in vitro which was shown in Mc Coy cytotoxicity test. Eighteen strains only were toxin A positive in vitro. From all isolated C. difficile strains 28% were tox A (-) tox B (+). By means of PCR presence of toxin A and toxin B genes was tested directly in faecal samples and in strains. From the same 50 faecal samples 17 B. fragilis strains were isolated. Four of them produced the enterotoxin (fragilisin) which was detected on the HT 29/C1 cell line. Genes of fragilisin were found in strains and directly in faecal samples. Toxin producing C. difficile and B. fragilis (ETBF) together were found in 3 samples. From one faecal sample only ETBF was cultured.

Adult↗

PubMed2000

Properties and actions of heat-stable enterotoxin of Escherichia coli.

The heat-stable enterotoxins (STs) produced by enterotoxigenic Escherichia coli are classified into two groups, methanol-soluble (STI) and methanol-insoluble (STII) enterotoxins. These are distinct toxins with unique properties. Their features in common include heat-stability, low molecular weight, secretion from the bacteria, and ability to induce fluid secretion from the intestine. STI is an 18- or 19-amino acid extracellular peptide with three intramolecular disulfide bonds, which is produced by proteolytic cleavage of 72 amino acid precursor. The STI in the lumen of the intestine binds to specific protein receptors (guanylate cyclase C) located in the brush border membrane and leads to elevation of intracellular cyclic GMP level. Several factors involved in the activation of guanylate cyclase by STI have been identified. Elevation of cyclic GMP level induces intestinal fluid secretion by stimulation of chloride secretion. Cystic fibrosis transmembrane conductance regulator, which is a chloride channel, might be involved in chloride secretion. In contrast, STII is a 48-amino acid peptide with two intramolecular disulfide bonds, which results from 71 amino acid precursor. Compared with STI, the steps that lead to intestinal fluid secretion by STII are not well established. It has been proposed that sulfatide in the brush border is a receptor for STII and that the STII bound to the receptor opens GTP-binding regulatory protein-linked calcium channels. These actions of STII induce not only stimulation of the production of secretagogues such as prostaglandin E2 and serotonin, but also activation of the calcium-calmodulin-dependent protein kinase II in the cells.

Animals↗

PubMed2001

Enterotoxins of Staphylococcus aureus induce a cytopathic effect in cell lines.

We describe the use of cell cultures for the detection of Staphylococcus aureus enterotoxins. Madin Darby Bovine Kidney (MDBK), Bovine Embryo lung cells (PEB) and Dog Carcinoma Cell line (A-72) cell monolayers were tested. MDBK, A-72 and PEB cell lines proved to be susceptible to the cytotoxic effect induced by staphylococcal enterotoxins. A cytopathic effect was observed in some cases after 2 hours of incubation. The PEB cell line was the most susceptible and may be used as a useful and cheap method for screening enterotoxigenic S. aureus strains.

Animals↗

PubMed2001

[Enterotoxin-producing Bacteroides fragilis strains isolated from horses].

Seven Bacteroides fragilis strains were cultured from samples collected from horses. From all the tested strains, as well as from the reference B. fragilis strains: enterotoxigenic NCTC 11925 and nonenterotoxigenic IPL 323 strain, DNA was isolated using Genomic DNA PREP PLUS isolation kit manufactured by A&A Biotechnology (Poland). To detect the enterotoxin (fragilysin) gene, polymerase chain reaction (PCR) was applied, using the following starters: 404 (GAG CCG AAG ACG GTG TAT GTG ATT TGT) and 407 (TGC TCA GCG CCC AGT ATA TGA CCT AGT). DNA obtained from bacterial cells was amplified in a thermocycler (Techne). The temperature profile was as follows: 1 cycle (4 min. 94 degrees C), 40 cycles (1 min. 94 degrees C, 1 min. 52 degrees C, 1 min. 74 degrees C). Amplification products were detected by electrophoresis in agarose gel (1%) with ethidium bromide added. The presence of the fragilysin gene was detected in two strains. Among the strains isolated from horses enterotoxin gene-possessing Bacteroides fragilis strains (ETBF) can be detected.

Animals↗

PubMedDate not supplied

Presence and characterization of sensitization to staphylococcal enterotoxins in patients with allergic rhinitis.

Exotoxins derived from Staphylococcus aureus appear to be involved in the pathogenesis of allergic diseases, especially atopic dermatitis (AD). However, little is known about sensitization to enterotoxins in cases of respiratory allergies. Because the nasal cavity is a primary site of colonization by S. aureus, we sought to determine the prevalence and role of serum immunoglobulin E (IgE) antibodies against staphylococcal enterotoxin A (SEA) and SEB in patients with allergic rhinitis (AR). The presence of SEA- and SEB-specific IgE was determined in 40 patients with AR and 16 healthy control subjects. In the rhinitis group, nasal symptom score, total serum IgE, sensitization to other inhaled allergens and the presence of sinusitis were determined. Twenty-five percent of patients with AR were sensitized to SEA/SEB whereas 6.3% of controls were sensitized to the toxins. Sensitization to SEB was predominant relative to SEA. There were no significant differences in the severity of nasal symptoms and complications of other allergic diseases including AD and bronchial asthma, between patients with or without sensitization to SEA/SEB. However, patients sensitized to these toxins were likely to show increased total serum IgE and polyvalent sensitization, suggesting that exposure and subsequent sensitization to SEA/SEB may be involved in polyvalent sensitization.

Adolescent↗

PubMed2001

[Adhesion of human granulocytes and T lymphocytes to vascular endothelial cells after stimulation with Bacteroides fragilis endotoxin and enterotoxin].

The aim of presented study was to estimates the number of human granulocytes and T lymphocytes adhering to 1 mm2 of vascular endothelial cell culture stimulated by Bacteroides fragilis endotoxins (LPS) and enterotoxin (BFT). HMEC-1 cells were activated with bacterial preparations at the concentration of 10 (micrograms/ml for 4 and 24 hours. Granulocytes and T lymphocytes were isolated from peripheral blood of healthy blood donors. The adhesion tests of granulocytes and adhesion tests of resting and activated with PMA (at the concentration of 10 ng/ml) T lymphocytes to the non-stimulated and stimulated by B. fragilis compounds (LPS and BFT) vascular endothelium were performed. The number of viable leukocytes, which adhered to the endothelium, was determined using inverted microscope (magnification 200x). The results were presented as the number of viable cells adhering to 1 mm2 of the endothelial cell culture. The results of experiments indicate that granulocytes and T lymphocytes (resting and after activation with PMA even in greater number) adhere to the endothelial cells stimulated by B. fragilis endotoxins and enterotoxin. B. fragilis toxins are weaker stimulants of human leukocyte adhesion to the HMEC-1 cells than E. coli O55:B5 LPS. B. fragilis LPS and BFT preparations stimulate endothelial cells to the adhesion of granulocytes in similar manner, whereas the activation of vascular endothelium to the adhesion of T lymphocytes is differentiated.

Bacteroides fragilis↗

PubMed2000

[The sifnificance and characteristics of the internal distribution of Staphylococcal enterotoxin B in burned rats with sepsis].

OBJECTIVE: To investigate the role of staphylococcal enterotoxin B (SEB) in the development of postburn staphylococcus aureus sepsis. METHODS: Rats inflicted with 20% TBSA III degree scald followed by Staphylococcus aureus sepsis were used as the experimental subjects. The distribution of SEB in the vital organs such as the heart, liver, lungs, kidneys and plasma was observed with concomitant serial measurement of the relative organ functional indices. RESULTS: The plasma SEB content increased transiently in the early stage of sepsis (P < 0.01) and then fell to near that of control group. The SEB contents in the heart, liver, lungs and kidneys increased evidently 2 hours after staphylococcus aureus challenging (P < 0.01) and continued to increase afterwards. The functions of multiple organs were impaired obviously at 24 postburn hours, and the function impairment was aggravated by S. aureus challenge. The degree of organ injury of liver and kidneys correlated positively with tissue content of SEB (P < 0.05 similar 0.01). CONCLUSIONS: Staphylococcal enterotoxin B might play a role in the development of MODS induced by postburn sepsis.

Animals↗

PubMed2002

[Enterotoxin production as a diagnostic test in intestinal dysbacterioses ].

The new approach to advancing diagnostic of dysbacterioses grounded on determination of the pathogenic factors of potential-pathogenic microflora is proposed. The method of reacting of an indirect hemagglutination with usage of erythrocital diagnosticums ostend availability of production of staphylococcal enterotoxines of types A and B in 40% of the strains of staphylococcuses, isolated at dysbacterioses. The intensity of production of staphylococcal enterotoxines for strains of microorganisms, isolated at dysbacterioses and carrying of S. aureus, and at food borne diseases, is various. The availability of clinical developments of an intestinal dysfunction in faeces of the patients contacts with persistence of enterotoxigenics S. aureus, and their elimination--with successful police of the disturbed microbiocenosis.

Bacterial Infections↗

PubMedDate not supplied

[Enzyme immunoassay system for detection of staphylococcal enterotoxin, type C].

An enzyme immunoassay (EIA) system for detection of staphylococcal enterotoxin, type C, has been developed. The sensitivity of the system is 1 ng/ml. The optimum EIA parameters have been worked out. The absence of false positive results with heterologous toxins confirms the specificity of the assay system. The possibility of the detection of staphylococcal enterotoxin, type C, in staphylococci isolated from different sources has been shown.

Enterotoxins↗

PubMedDate not supplied

[Determination of thermostable and thermolabile enterotoxins in Escherichia coli strains by genetic, biological, and immunoserological methods].

The Escherichia coli strains (75) isolated from patients suffering from diarrhea were screened for ability to produce the temperature-labile or stable toxins (ST or LT) by the different techniques (the hybridization with DNA probes, biological, enzyme immunoassay). The majority of tested strains was shown to harbor the tox-genes controlling the synthesis of ST, LT or both enterotoxins. However, the phenotypic expression of the genes was registered in only some of the strains. The hybridization with the DNA probes is noted to be most perspective in the mass screening of toxigenic strains. The DNA probe used contained the fused estA-eltB genes that makes one able to detect the genes for both enterotoxins.

Bacterial Toxins↗

PubMed1992

Effects of thermostable Escherichia coli enterotoxin peptide on the isolated rat kidney.

In order to compare the function of sodium transport between the intestine and renal tubule, we studied the effect of thermostable E. coli enterotoxin on rat kidneys. Isolated kidneys from adult male hooded rats weighing 240-335 g were perfused with Krebs-Henseleit solution containing 60 mg/ml dialyzed bovine serum albumin. The effects of E. coli enterotoxin (STa; molecular weight approximately 2000; 18 amino acids with three disulfide bonds) were studied on glomerular filtration rate (GFR), net urinary flow rate (UF) and fractional sodium reabsorption (% TNa+). All experiments were preceded by a 30-min control period, and in some kidneys the time course of the variables was followed without toxin infusion, for a paired control. STa (0.1 microgram/ml) infused into the perfusate 30 min after the beginning of the experimental period promoted a significant decline in % TNa+ from 78.4 +/- 1.6 (control period) to 51.6 +/- 6.8 (P < 0.001) 90 min after the administration of the toxin. This effect was followed by an increase in net urinary flow (UF) in toxin-treated kidneys (UFSTa = 0.120 +/- 0.009 vs UFcontrol = 0.056 +/- 0.011 ml g-1 min-1, P < 0.008). The GFR of control and STa-treated kidneys did not change during the total time of perfusion and after toxin infusion. Our data demonstrate that STa promotes a specific decrease in tubular sodium transport in the rat kidney.

Animals↗

PubMed1992

In vivo induction of apoptosis in immature thymocytes by staphylococcal enterotoxin B.

Staphylococcal enterotoxins are potent T cell mitogens. Recent studies have shown that the binding of these toxins to class II MHC molecules on accessory cells is essential for the stimulation of T cells which bear specific V beta segment of TCR. In the present study we show that i.v. administration of staphylococcal enterotoxin B (SEB) results in an enlargement of spleen and lymph nodes but causes thymus atrophy. Elimination of CD4+CD8+ cells predominantly accounted for the shrinkage of thymus, and the lowest level of this cell population was reached 4 days after SEB injection. Furthermore, this decrease in CD4+CD8+ cells was accompanied by a relative increase in the percentages of CD4+CD8-, CD4-CD8+ and CD4-CD8- cells, whereas their absolute numbers actually reduced on day 4. The thymus shrinkage involved apoptosis which was characterized by DNA fragmentation and morphologic changes. The depletion of Thy-1 high, TCR-alpha beta low and TCR-alpha beta intermediate cells also occurred with a kinetic correlated to the reduction of CD4+CD8+ cells. Our results further showed that the percentages of V beta 8+ cells reduced 12 h post SEB injection, increased after 2 days, and decreased again thereafter. SEB thus causes both apoptotic and stimulative effects in the thymus. Apparently, the tremendous loss of double-positive cells (greater than 90% in cell number on day 4) is not simply due to the reduction of V beta 8+ cells, the possible modulatory effect of other factors or hormones which may play a role in the cell death is discussed.

Animals↗

PubMed1976

Effect of cholera enterotoxin preparations on cutaneous response in rabbit under varied conditions.

Enterotoxic activity of two preparations obtained from Vibrio cholerae, B-53-6 Inaba and B-53-10 Ogawa was tested in ligated ileal loops of rabbit. The biologically active enterotoxic preparations were further used to study the permeability reaction in rabbit skin. Cutaneous response tended to be linear only with higher concentrations of the toxin and showed maximum blueing intensity between 16 and 24 hrs of intracutaneous inoculation. Exposure of enterotoxin preparations to elevated temperatures greatly reduced the cutaneous response and the activity was completely lost at 100 degrees C. Change in pH towards alkaline side lowered the permeability activity to lesser extent as compared to a shift on acidic side. However, a residual activity could still be detected when pH of the enterotoxins was lowered to 3 at 30 degrees C for 4 hrs.

Animals↗