export_ssti bacteria ii Flashcards
Alpha-hemolysis
Green coloration
Beta-hemolysis
Complete hemolysis
Gamma-hemolysis
No color change or lysis
Lancefield Ags
A, B, and D
Distinguish between Strep. species
A Lancefield Ag
Found in S. pyogenes
B Lancefield Ag
S. agalactiae
D Lancefield Ag
S. bovis
Enterococcus
Strep. without Lancefield Ag
S. pneumoniae
S. mutans
Group A strep disease
S. pyogenes
Strep throat
S. pyogenes features
Beta-hemolytic
Sensitive to Bacitracin
S. pyogenes virulence factors
Capsule
Adhesins (F and M protein, LTA)
Toxins (streptolysin O and S, superantigens)
LTA
Adhere to fibronectin
F and M protein
Invasion of epithelial cell
M protein
Anti-phagocytic
Inhibits complement
Facilitates cell invasion (fibrinogen, Ig, factor H)
Streptolysin O and S
Pore forming toxins
Allow invasion and destruction of cells/tissues
Strep. superantigens
SPEs
Proinflammatory cytokine response
C5a peptidase
Degrades C5a (chemoattractin that brings PMNs to site of infection)
SSTI by S. pyogenes
Impetigo
Erysipelas
Cellulitis
Necrotizing fasciitis
What is the most common cause of cellulitis?
S. pyogenes
Diagnostic symptom of necrotizing fasciitis
Pain and tenderness are usually severe
Difference between cellulitis and necrotizing fasciitis
Cellulitis generally looks worse early on, and is less painful
Treatment of necrotizing fasciitis
Debridement of area
Antibiotics are supplemental
Scarlet fever
Complication of GAS pharyngitis
Caused by SPE toxin
Diffuse erythematous rash
Acute rheumatic fever
Complication of GAS pharyngitis
Cross-reactive Abs attack joints, heart valves, etc.