FIG. 2.

Frequency distribution of the productivity of SEG, SEH, and SEI by S. aureus isolates. All S. aureus isolates were grown in brain heart infusion broth-1% yeast extract at 37°C for 48 h. The culture supernatants were preincubated with 20% (vol/vol) normal rabbit serum overnight and were diluted with phosphate-buffered saline-Tween 20 to reduce the background caused by protein A. These pretreated culture supernatants were each subjected to sandwich ELISA, and the concentrations of SEG, SEH, and SEI were determined by use of standard curves.