Assay of Staphylococcal Enterotoxin from Cheese

Read, R. B.; Bradshaw, J. G.; Pritchard, W. L.; Black, L. A.

doi:10.3168/jds.s0022-0302(65)88246-7

Cited by 18 publications

(7 citation statements)

References 10 publications

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“…Methods for immunodiffusion in agar, quantitative precipitin assays, hemagglutination (HA)-inhibition, and immunofluorescence have been described for this purpose (8,9,11,15,17,21,23). Measurement of enterotoxin in food samples by immunofluorescence, a micro Ouchterlony technique, and the single diffusion technique of Oudin have been described, as have the procedures necessary to eliminate nonspecific proteins and salts that influence the results (4,12,13,14,19,20). HA-inhibition, passive HA, and the quantitative precipitin test have not been used with food samples.…”

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

Silverman¹,

Knott²,

Howard³

1968

Applied Microbiology

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Reversed passive hemagglutination was used to assay enterotoxin in culture filtrates and in food samples. With cells tanned and then sensitized with antitoxin globulin and preserved with either formaldehyde or pyruvic aldehyde, as little as 0.0007 ,ug of enterotoxin was detectable. The results of hemagglutination tests compared well with those obtained by quantitative precipitin tests or by immunodiffusion, but hemagglutination was 50 to 100 times more sensitive than the immunodiffusion technique. In addition, results of the hemagglutination test were available within a few hours, and neither elimination of interfering proteins from food extracts nor concentration of the sample, both of which are necessary for immunodiffusion, was required for this procedure.

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

Silverman¹,

Knott²,

Howard³

1968

Applied Microbiology

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“…Many previously recommended methods are based on the use of ion-exchange material for partial purification of enterotoxins from the food extract (Read et al, 1965a;Gilbert et al, 1972;Reiser et al, 1974). Reiser et al (1974) have proposed a shortened method utilizing batch adsorption of the enterotoxins into ion-exchange *Casman and Bennett, 1965;Hall et al, 1965;Read et al, 1965a, b;Stojanow and Schenk, 1966; Zehren and Zehren, 1968; Gilbert et al, 1972;Reiser et al, 1974;Niskanen and Lindroth, 1976 resin and proteolytic digestion of the partially purified extract.…”

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Suitability of the enzyme treatment and ammonium sulfate precipitation method for detection of staphylococcal enterotoxin from different foods

Niskanen

Lindroth

1977

European J. Appl Microbiol.

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Summary. An enzyme treatment and ammonium sulfate precipitation procedure was adapted to the detection of staphylococcal enterotoxin from high-protein foods. The enterotoxin is extracted from food with distilled water, after which soluble proteins are acid-precipitated (pH 4.5) and the supernatant washed with chloroform (pH 7.5). The extract is then treated with trypsin and Pseudomonas peptidase for 2 h at +37~Residual unhydrolyzed material is precipitated with 60% ammonium sulfate for 15 min at +4~The precipitate is redissolved in phosphate buffer and concentrated by dialysis against polyethyleneglycol. The concentrate is washed with chloroform and lyophilized. The dry material is dissolved in 0.2 ml distilled water and enterotoxin detected by the micro-slide method with 24 h incubation at +37~ Using this method, it has been possible within three days to detect 0.2-1.0/~g staphylococcal enterotoxin A added to minced meat, dry sausage, smoked fish, cheese and milk.

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“…Methods for immunodiffusion in agar, quantitative precipitin assays, hemagglutination (HA)-inhibition, and immunofluorescence have been described for this purpose (8,9,11,15,17,21,23). Measure (4,12,13,14,19,20). HA-inhibition, passive HA, and the quantitative precipitin test have not been used with food samples.…”

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“…After standing for 45 min at room temperature, they were centrifuged at about 15,000 X g for 20 min in a Servall SS-1 centrifuge at 4 C. The clear liquid portion between the sediment and the top fat layer was removed with a syringe having an 18-gauge needle and then was filtered through a single layer of paper towel (Scott Wipers 590, Scott Paper Co., Chester, Pa.) (14). Cheese and milk were prepared essentially as described by Read et al (19,20). The culture filtrate containing enterotoxin was added to the homogenized cheese or directly to the milk before separation of the whey.…”

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

Silverman¹,

Knott²,

Howard³

1968

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(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.

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Assay of Staphylococcal Enterotoxin from Cheese

Cited by 18 publications

References 10 publications

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

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

Suitability of the enzyme treatment and ammonium sulfate precipitation method for detection of staphylococcal enterotoxin from different foods

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

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