Evaluation of Identification Methods for Staphylococcus aureus and Development of Modified Detection Methods for Staphylococcal Enterotoxin A

Abstract

We evaluated whether the agar plate method using a Baird Parker + rabbit plasma fibrinogen (RPF) agar could be used in place of the combination of a latex agglutination test (PS-latex) and a tube coagulase test for identification of Staphylococcus aureus from other strains of staphylococci. The PS-latex and tube coagulase tests showed positive results for 96 (100%) and 87 (90.6%) S. aureus strains, respectively. However, the PS-latex test showed positive results for 32 non-S. aureus strains. On the other hand, the agar plate method was positive for all the strains of S. aureus and showed no false-positive or -negative results. Next, we developed a highly sensitive and selective enzyme-linked immunosorbent assay (ELISA) for the detection of staphylococcal enterotoxin A (SEA). The interference by protein A and an unknown protein were eliminated using proteolytic digestion. This improved method is useful for SEA detection.