Editing Group A streptococcal infection (section)

== Diagnosis ==
[[File:Diagnostic algorithm of possible bacterial infection.png|thumb|Example of a workup algorithm of possible bacterial infection in cases with no specifically requested targets (non-bacteria, mycobacteria etc.), with most common situations and agents seen in a New England setting. Main ''Streptococcus'' groups are included as "''Strep.''" at bottom left.]]
Diagnosis is by a swab of the affected area for laboratory testing. A [[Gram stain]] is performed to show Gram-positive cocci in chains. Then, the organism is cultured on [[blood agar]]. The rapid pyrrolidonyl arylamidase (PYR) test is commonly used, wherein a positive reaction confers a presumptive identification of group A beta-hemolytic streptococci if the appearance and clinical context is consistent. GBS gives a negative finding on the PYR test.<ref>{{cite web|url=http://microbeonline.com/pyrrolidonyl-arylamidase-pyr-test-principle-procedure-results|title=Pyrrolidonyl Arylamidase (PYR) Test: Principle, procedure and results—microbeonline|date=12 November 2013}}</ref> There are also latex agglutination kits which can distinguish each of the main groups seen in clinical practice.