Detection of staphylococcal enterotoxin H by an enzyme-linked immunosorbent assay

A double-antibody sandwich enzyme-linked immunosorbent assay (ELISA) was developed for the detection of a newly identified staphylococcal enterotoxin H (SEH). Peroxidase was conjugated to antibodies specific to the enterotoxin. 2,2'Azino-bis(3-ethylbenz-thiazoline-6-sulfonic acid)(ABTS) in hydrogen peroxide solution was used as the enzyme substrate. A standard curve of purified SEH was prepared with concentrations ranging from 1.3 to 50 ng/ml. SEH at levels equal to 2.5 ng/ml and higher were detected by this procedure. Culture supernatant from the growth of selected Staphylococcus aureus strains was analyzed by using the ELISA. SEH was produced by three of 20 strains that produced one identified enterotoxin. Ten of 21 strains, previously shown to produce substances that induced emesis in monkeys but not any known enterotoxins (A through E), were also positive for SEH production. The other 11 strains gave negative results in the ELISA, indicating that other unidentified serological types of enterotoxin exist.