Streptococcus pyogenes (Group A Strep)

Gram Stain

• Gram positive cocci in chains (aerobic)

Clinical Significance

This organism is associated with pharyngitis, skin/soft tissue infections (including necrotizing cellulitis/fasciitis), endocarditis, meningitis, postpartum sepsis, bone/joint infections, pneumonia, septicemia, and toxic shock-like syndrome.

S. pyogenes pharyngitis may be associated with acute rheumatic fever and glomerulonephritis.

Usual Susceptibility Pattern

This organism is susceptible to penicillin.

Resistance to macrolides and clindamycin is significant.

Although historically thought to be inherently resistant to TMP/SMX, this is now thought to have been an in-vitro effect and hence susceptibility is likely variable.  There is insufficient evidence to recommend this agent empirically for serious infections.