Crude, concentrated extra-cellular supernatants from Legionella pneumophila produced a soft-tissue necrosis, demonstrated by intraperitoneal or sub-cutaneous injections into infant mice. The reaction ...was rapid and gave a hemorrhagic tissue necrosis within minutes. Being heat-labile, this tissue reaction is different from those of a heat-stable cytotoxin and a heat-stable hemolysin previously described.
One hundred and seventy-seven Escherichia coli strains isolated from food, pigs and humans were tested for the production of heat-labile and heat-stable enterotoxin at 4, 22, and 37 degrees C. ...Heat-labile enterotoxin was detected in culture supernatants by an enzyme-linked immunosorbent assay, and heat-stable enterotoxin by the infant mouse bioassay. Thirty strains produced heat-labile enterotoxin, and twenty heat-stable enterotoxin. None of the strains isolated from food were enterotoxigenic. Fifty-seven per cent of the human and porcine strains producing heat-labile enterotoxin at 37 degrees C also produced the toxin at 4 degrees C. The fact that Escherichia coli enterotoxin may be present in food at consumption must be considered pathogenetically relevant.
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.
Toxoplasma gondii IgG antibodies were measured in 212 goat sera, comparing the Sabin-Feldman dye-test and a three-layer sandwich enzyme-linked immunosorbent assay (ELISA). With 98 % concordance ...obtained between these 2 tests, the results are at the same paragon as for human sera. Accordingly, the ELISA sandwich procedure appears to be suitable for large-scale analysis of goat sera. The discordant 2
%
were ELISA positive and dye-test negative. One possible explanation of the divergent titres is given using an immunized goat model.
Heat-labile enterotoxin producing strains of Escherichia coli were isolated from diarrheal faeces of humans and from the jejunum of pigs which had died of diarrhea. The heat-labile enterotoxin was ...assayed by three different enzyme-linked immunosorbent assays (ELISA). The first assay was based upon immunological cross-reactions between the heat-labile enterotoxins of E coli and Vibrio cholerae, the second on specific E coli heat-labile enterotoxin antibodies and the third on affinity of the toxin to the presumed cell membrane receptor, the ganglioside GM1. The heat-labile enterotoxins of human and porcine origin bound equally well to the same extent in the ELISA procedure, which utilized immunological cross-reactivity between the heat-labile enterotoxins of E coli and V cholerae. The reactivity, however, was quite different in the GM1-ELISA. The binding affinity was high between GM1 and enterotoxin produced by E coli strains of human origin, whereas the binding affinity was low for enterotoxin from porcine strains.
The production of enterotoxins by strains of Staphylococcus aureus of human and animal origin seems to be common. 104 out of 170 strains (61%) produced one or more of the A, B, and C enterotoxins. ...Strains from cow and milk often produced enterotoxin C, and enterotoxin A producing strains were mainly isolated from dogs. Human food poisoning seemed in our material to be induced by enterotoxin A producing strains.
Staphylococcus aureus enterotoxins A, B, and C, were detected by means of a four-layer sandwich ELISA method. With toxin produced in broth supernatants, this ELISA method had a detection limit of 0.5 ...ng enterotoxin per ml. Conjoint with enterotoxin, S. aureus most often produces protein A. The protein A will interfere and produce false positive reactions in a sandwich ELISA, by binding nonspecifically the IgG in different layers, simulating the immunospecific toxin binding. With rabbit IgG coupled to Sepharose CL-4B gel, 99% of protein A could be removed from solutions, bringing the level under the interfering limit in the ELISA.
PDF
