S. pyogenes is "flesh-eating" bacteria. It results from life-theatening myonecrosis caused by this organism. S. pyogenes avoids phagocytosis (mediated primarily by capsule, M and M-like proteins, C5a peptidase), adhere to and invade host cells (M protein, lipoteichoic, F protein), and produce toxins (streptococcal pyrogenic exotoxins, steptolysin S, streptolsin O, streptokinase, DNases).
Suppurative diseases: pharyngitis, soft-tissue infections.
Erysipelas: localised skin infection with pain, inflammation, lymph node enlargement and systemic symptoms.
Cellulitis: infection of the skin that involves the subcutaneous tissues.
Necrotising fasciitis: deep infection of skin that involves destruction of muscle and fat layers.
I think these are most its skin infections. But what about its diagnostics?
I think take biopsy from living tissue, not from necrotic. If pus, then probably from it. I think we can do Gram staining, recognise gram-positive cocci like in a string Then, we can do hydrogen peroxide test - if no bubbles, then suspicion to S. pyogenes, since catalase negative. The do optochin test which is positive for S. pyogenes.
What is the correct procedure for doing skin infection diagnostics for group A streptococci?