A reagent for the detection of an extracellular enzymatically active protein produced by a beta-hemolytic streptococcus bacteria found in a host biological fluid includes a proteinaceous substrate or a cholesterol-containing membrane substrate for the extracellular protein. The substrate is nonspecific within the groups of beta-hemolytic streptococcus bacterium and is in contact with an inert solid matrix. Upon reaction between the streptococcus enzymatically activate protein and the substrate, a color change discernable by an unaided human eye results. Extracellular streptococcus protein found in saliva represents a less invasive source of biological fluid for the determination as to whether a host suffers acute pharyngitis.