Final answer:
Streptolysin S is an oxygen-stable enzyme produced by Streptococcus pyogenes, and it is not used as a serologic indicator because it is not antigenic. Its presence is detected by its biochemical actions rather than by DNA analysis.
Step-by-step explanation:
Streptolysin S is an oxygen-stable enzyme produced by Streptococcus pyogenes, also known as group A streptococcus (GAS). This enzyme is one of the extracellular enzymes, along with streptolysins O, hyaluronidase, and streptokinase, that contribute to this bacterium's ability to cause disease and provoke an inflammatory response. It is not antigenic, which means it does not stimulate an antibody response during infection, and thus is not used as a serologic indicator of a recent streptococcal infection. Streptolysin S's presence is not typically detected by DNA analysis, but rather by its biochemical action, such as its ability to cause hemolysis on blood agar plates.