Biomedical subjects
Publications and source records attributed to F S Fluer.
A highly sensitive and specific enzyme immunoassay system for the determination of staphylococcal toxic shock exotoxin (TSE), permitting the detection of TSE at a concentration of 5-10 ng/ml, has been developed. The possibility of using this assay system for the selection of TSE-producing strains has been shown. 84% of staphylococcal strains under study have been found to produce TSE.
The authors suggest a simple and rapid technique, staphylococci coagglutination, for rapid detection of the toxic shock exotoxin (TSE)-producing S. aureus strains. The method is based on the sensitization of formalin-treated Cowan-1 S. aureus cells with immunoglobulins to TSE. The reagent thus obtained coagglutinates with the supernatant of TSE-producing S. aureus tested strains. This method is more sensitive than the routinely used gel immunoprecipitation. The technique for preparing the supernatant of S. aureus tested cultures is also described.
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The possibility has been demonstrated of using the method of aggregate-haemagglutination for the detection of B. cereus exo-enterotoxin in both food products and culture media. It has been established that 0.004 mug/ml of enterotoxin can be detected by this method. The applied antisera to B. cereus enterotoxin did not yield cross reactions with enterotoxins produced by E. coli, Cl. perfringens, St. aureus, V. cholerae or Sh. dysenteriae.
The authors elaborated a method of purification of staphylococcus enterotoxin, type B, consisting of three stages: the first stage--lyophilization and dialysis of the culture fluid against distilled water for 36 hours, the second stage--precipitation of dialyzed preparation with 2 volumes of ethanol at --15 degrees C, and the third stage--gel-chromatography of the enterotoxin preparation precipitated with alcohol on a column with Sephadex G-100 in a 0.015 M solution of NaCl (pH 7.0). Preparation isolated by the mentioned method possessed enterotoxic activity in a dose of 0.015 mg of protein per 1 kg of cat weight; by antigenic composition it represented a two-component system. In immunization of rabbits with a purified enterotoxin preparation an antiserum with the prevalence of antibodies to enterotoxin, type B, was obtained.
The possibility of using the aggregate-hemagglutination technique for detection of Bacillus cereus exo-enterotoxin in foodstuffs and culture media is shown. A 0.004-mug quantity of enterotoxin per ml can be detected by this method.
"Sandwich" variant of ELISA was used to identify staphylococcal enterotoxins (SE), types A and B, in S. aureus filtrates inducing food poisoning, in extracts of the lactic acid product for infants "Biphilin" that caused staphylococcal infection, and in foods contaminated with SE in varying concentrations. It has been shown that ELISA used for SE identification in foods permits revealing SE, types A and B, in liquid products in concentrations of 1-2 ng/ml (that is 1000-fold more sensitive, than the immunodiffusion test, 400-800-fold more sensitive than the passive hemagglutination test, and 10-fold more sensitive than the indirect passive hemagglutination test), and in solid products--in concentrations of 5-10 ng/g (after artificial contamination).
The activity of lecithaniase was determined in 24 strains of Bacillus thuringiensis on four growth media. The highest accumulation of lecithinase was found on the Hottinger medium containing 0.5% of glucose and 0.56% of sodium bicarbonate. Lecithinase appears at the logarithmic growth phase, and its activity is maximal after 10 hours of growth (at the beginning of the stationary phase). Biosynthesis and accumulation of lecithinase occur at pH 6.0 to 9.0. Lecithinase was purified by salting out with ammonium sulphate (75% saturation). Lecithinase is a thermolabile protein; it is stable within pH range of 3.0 to 9.0 and is resistant to the action of trypsin and 8M urea.
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