A Rapid Sensitive Assay for Staphylococcal Enterotoxin and a Comparison of Serological Methods

Abstract

(8,9,11,15,17,21,23 (4,12,13,14,19,20Formalin-preserved sheep erythrocytes (SRBC) were obtained from Difco. They were washed once with 0.038 M NaHSO, in 0.85% saline and then twice with saline. We observed previously (Bacteriol. Proc., 1966, p. 43) that formaldehyde decreases the serological activity of enterotoxin B; therefore, the initial washing with NaHSO, was included to neutralize free aldehyde. Fresh SRBC, collected in an equal volume of modified Alsever's solution (3), were treated with pyruvic aldehyde as described by Ling (16).Antienterotoxin globulin was prepared from rabbit antiserum by saturation with (NH4)2SO4 to 50%. The precipitate was washed several times with 50% saturated (NH4)2SO4, dialyzed against 0.15 M boratebuffered saline (pH 8.4) until free of S042-ions, and then freeze-dried and stored at 4 C. Approximately 90% of the antibody was recovered. Rabbits were immunized as described previously (21). Recent data have indicated that initial injections of toxoid in Freund's adjuvant into the foot pad, followed after 3 to 4 weeks by intravenous injections of alum-adsorbed toxoid and the alum-adsorbed toxin, produce high-1019 Vol. 16,No. 7 Printed in U.S.A.

Rapid and sensitive method for quantitation of Legionella pneumophila serogroup 1 antigen from human urine

“…The reversed passive hemagglutination (RPHA) test has been successfully used in the past for detection or assay or both of tetanus toxin (2) and staphylococcal enterotoxin B in culture fitrates and in food samples (5).…”

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“…A considerable amount of immunoglobulin other than homo-specific immunoglobulin is present in the immunoglobulin obtained through gel filtration on Sephadex G-200 or by DEAE-cellulose chromatography performed after sedimentation with ammonium sulfate. The presence of impurities in fractionated immunoglobulin is considered to be the cause of the non-specific reaction reported by Silverman et al (13) and Bennett et al (1). Therefore, in this …”

“…In 1968, Silverman et al (13) proposed RPHA for the assay of enterotoxin B in food or culture filtrates. In routine practice, however, many researchers (1,2) pointed out the occurrence of false positives or cross-reactions among the toxin types.…”

Comparison of different purification procedure for extraction of staphylococcal enterotoxin A from foods

“…Heat treatment has been used in some extraction methods (2,24) and has been considered to have a positive effect in reducing the level of components interfering with the microslide method. The high loss of SEA (50%) and corresponding low loss of TN (15%) observed in our research indicate that this method is rather unsound.…”