Streptococci Flashcards
facultative anerobes
streptococci
alpha-hemolytic strep
S. pneumococci, and viridans
beta-hemolytic strep
S. pyogenes, S. agalactiae
gamma-hemolytic strep
S. salivarius
Group A strep
S. pyogenes
Group B strep
S. agalactiae
Streps that are untypable by the Lancefield system
S. pneumoniae and viridans
strep are catalase _____
negative
staph are catalase _____
positive
strep are oxidase _____
negative
Neisseria are oxidase
positive
GAS diseases
Pharyngitis Scarlet fever (uncommon) Puerperal sepsis (uncommon) Erysipelas Septicemia Tonsilits Cellulitis Impetigo Necrotizing fasciitis Toxic shock syndrome
Sequelae of GAS
acute rheumatic fever (ARF) acute glomerulonephritis (AGN)
Sequela of GAS pharyngitis
ARF
Rheumatic heart disease epidemiology
low-income, developing countries
Sequela of GAS skin infections
acute glomerulonephritis
ARF and AGN are _____-mediated diseases
immune
Oxygen stable GAS hemolysin
streptolysin S (SLS)
Oxygen sensitive GAS hemolysin
streptolysin O (SLO)
GAS virulence factors
SLS/SLO hyaluronic acid capsule M protein lipteichoic acid (LTA) Streptococcal pyrogenic exotoxin A (SpeA), SpeB, etc.
Hyaluronic acid capsule VF mechanism
S. pyogenes hyaluronic acid is identical to huma hyaluronic acid. Antiphagocytic. No antibodies against it.
Stain that allows you to see hyaluronic acid capsule
india ink
Sortase-anchored surface protein. C-terminal half is conserved. N-terminus useful for serotyping. Major antophagocytic factor. Adhesin.
M protein
Adhesin. PAMP that causes innate immune cells to secrete cytokines and chemokines (not as powerful as LPS from gram negative bacteria)
Lipoteichoic acid (LTA)
