Concentration of Staphylococcal Enterotoxin from Food Extract Using Copper Chelate Sepharose.

A simple and rapid method is described for detecting as little as 1 ng each of staphylococcal enterotoxins A, B, and C in 100 mL samples of food extracts. Samples were fractionated on copper chelate Sepharose 6B and the recovery of added staphylococcal enterotoxin was measured by the reversed passive latex agglutination test. An approximate 100 fold concentration of toxin was obtained.

Purification of an Escherichia coli serogroup O157:H7 verotoxin and its detection in North American hemorrhagic colitis isolates.

Verotoxin (VT), which is immunologically unrelated to VT1 (Shiga-like toxin I), was purified from the culture filtrate of Escherichia coli hemorrhagic colitis serogroup O157:H7 strain 3657 by copper ion chelate affinity chromatography followed by anion-exchange chromatography. The isoelectric point by sucrose density gradient isoelectric focusing was 5.0, the molecular weight by gel filtration on Superose 12 was about 60,000, and the 50% cytopathic dose for Vero cells was about 1 pg.

Evaluation of radioimmunoassay performance for staphylococcal enterotoxin in foods: application of external quality assessment survey.

An external quality assessment survey for staphylococcal enterotoxin A, B, and C2 determinations was performed in the collaborative study. Three analysts in two laboratories took part. Three types of food, cheese, salami, and pasta, were artificially contaminated with either one toxin only or all three toxins.

Staphylococcus aureus Growth and Thermostable Nuclease and Enterotoxin Production in Canned Salmon and Sardines.

Staphylococcus aureus growth, thermostable nuclease (TNase) and enterotoxin production in inoculated canned salmon incubated at 22 ± 1°C for 4 d were dependent on the size of inoculum, and on the amount of oxygen present in the headspace; under nitrogen with an inoculum of 7 cfu/can, 10-10 cfu/g, no TNase and traces of enterotoxins (A, B, C) were observed; under oxygen with the same inoculum ≥10 cfu/g, ≥6.0 μg TNase and up to 5.2 μg total enterotoxins (A, B, and C)/100 g of salmon were observed.

Breakfast and performance in school children.

The results from two studies are reported of the effects on mental performance of omitting breakfast. The objective of the first study was to compare the performances of schoolchildren who habitually ate or did not eat breakfast. In the second study the effects of omitting breakfast by those accustomed to eating the morning meal were investigated.

Improved radioimmunoassay of Staphylococcal enterotoxin a.

A simple solid-phase radioimmunoassay was developed for detecting staphylococcal enterotoxin A (SEA) in food. The method detected 85-100% SEA added to extracts of 6 kinds of foods, and 52-100% SEA added directly to foods at a concentration of 1 ng/g. Assay sensitivity is about 0.

Comparative studies of five heat-labile toxic products of Escherichia coli.

Five heat-labile, partially purified toxic products of Escherichia coli were distinguished by isoelectric focusing, molecular weight, and neutralization with homologous and heterologous antisera. Only two affected the morphology of Y-1 cells, induced fluid accumulation in rabbit ileal loops, and stimulated production of cyclic AMP in Vero cells; these two did not cross-neutralize and only one showed cross-neutralization with cholera antitoxin. The remaining three products were cytotoxic for Vero cells.

Properties of an Escherichia coli cytotoxin.

Isoelectric focusing of a heat-labile cytotoxin of Escherichia coli H30 revealed the presence of two molecular variants, pI 7.2 and a comparatively small quantity of pI 6.8.

Rapid solid-phase radioassay for staphylococcal protein A.

Solid-phase radioassay was applied to the determination of protein A after release from staphylococcal cells with lysostaphin. Assays can be completed in 60-90 min.

Detection of staphylococcal enterotoxin in gastric juice.

The gastric juice of a patient showing symptoms of staphylococcal food poisoning was examined by a radioimmunoassay for the presence of enterotoxins. Assays gave markedly higher results at 35 degrees than at 5 degrees. The source for this discrepancy was attributed to interference due to trypsin activity on the basis of (1) the demonstration of hydrolysis of p-toluenesulfonyl-L-arginine methyl ester by the specimen, (2) inhibition of this activity by trypsin inhibitor from lima bean, and (3) lowered values produced for enterotoxins in gastric juice when the inhibitor was included in the assay system.

Double-antibody radioimmunoassay for staphylococcal enterotoxin C2.

A sensitive double-antibody radioimmunoassay for staphylococcal enterotoxin C2 is described. The assay procedure employs anti-rabbit gamma globulin, prepared in goats, to precipitate the antigen-antibody complex of enterotoxin C2 and anti-enterotoxin C2. The test is sensitive to 100 pg of enterotoxin.

The application of QAE-Sephadex for the purification of two staphylococcal enterotoxins. II. Purification of enterotoxin A.

The last three steps described in the preceding communication Robern, H., Stavric, S. and Dickie, N.

The application of QAE-Sephadex for the purification of two staphylococcal enterotoxins. I. Purification of enterotoxin C2.

A new method developed for purification of enterotoxin C2 from Staphylococcus aureus strain 361 consisted of four steps: batchwise adsorption from culture supernatant on QAE-Sephadex; gel filtration on Sephadex G-100; chromatography on QAE-Sephadex using a buffer of constant pH and molarity; and gel filtration using a volatile buffer of constant pH and molarity; and gel filtration using a volatile buffer as the eluting solvent. The purified enterotoxin appeared homogeneous by gel immunodiffusion, gel chromatography and in the analytical ultracentrifuge, although an apparent heterogeneity was noted on QAE-Sephadex chromatography and polyacrylamide disc electrophoresis at pH 4.5.