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.

Inhibition of Biological Activity of Staphylococcal Enterotoxin A (SEA) by Apple Juice and Apple Polyphenols

“…Cell proliferation was determined by a spectroscopic method that measures the incorporation of BrdU into newly synthesized DNA (27). Because rapid enzyme-linked immunosorbent assays (ELISAs) that have been developed for SEA do not distinguish between active and inactive toxins present in solution, we adopted our previously reported method to measure the effect of SEA on spleen cells based on the use of BrdU-labeled DNA (37). Figure 1 illustrates the observed linear relationship between the SEA concentration ranging from 0.01 to 1000 ng/mL and the amount of newly synthesized DNA measured spectrophotometrically (n = 3; R = 0.98).…”

“…Inhibition of SEA by Apple Polyphenols (Apple Poly). A possible explanation for the observed differences in the extent of toxin inhibition between freshly prepared Red and Golden Delicious juices is that the Red Delicious apple variety is reported to contain higher levels of phenolic compounds than are present in Golden Delicious apples (36)(37)(38). To obtain additional evidence for this suggestion, we examined the ability of a concentrated commercial apple polyphenol to inhibit the superantigenic activity of SEA.…”

Production of Staphylococcal Enterotoxin A in Cooked Rice and Limitation of its Organoleptic Detection

“…The specificity of SEA detection used in these studies was low, and the estimated values were unreliable in terms of quantitative analysis. The SEA concentration can be more precisely estimated using Western blot analysis, since this method is more sensitive and specific than other assays (Rasooly and Rasooly, 1998;Shimamura and Murata, 2009). Temperature control is important for the prevention of SFP in cooked rice.…”

Selection, identification and application of a DNA aptamer against Staphylococcus aureus enterotoxin A

“…Enzyme-linked immunosorbent assays (ELISA) for SEA are commercially available, are commonly used in the laboratory and demonstrate a good level of detection. 11,12 With the development of multi-scale technologies, biosensors have played an increasingly important role in the ultra-sensitive detection of SEA, such as in surface plasmon resonance (SPR), quartz crystal microbalance with dissipation (QCM-D) and hydrogel-based microarrays. [13][14][15] However, these advanced methods, which are based on antibody recognition with affinity, are limited to the strict conditions of the immunoassays.…”