Ch. 22 - Streptococcus

Question 1

Streptococcus

Answer 1

G+c in chains
FA
Ferment carbs --> lactic acid
CAT -
Hemolytic
Lancefield antigen in cell wall

Question 2

Strep. pyogenes

Answer 2

G+c in chains
Group A beta hemolytic Strep.
Most common cause of bacterial pharyngitis
Flesh eating bacteria

M protein --> virulence
(Class I and II; only Gp. A with class I M protein causes rheumatic fever)

Treat with Penicillin

Question 3

Strep pyogenes exotoxin

Answer 3

Pyogenic exotoxin (superantigen cytokine release)

Streptolysin O and S –> lyse blood cells

Streptokinase

Question 4

Strep. pyogenes supprative disease

Answer 4

Pharyngitis (can also see rheumatic fever with M protein I)
Pyoderma (impetigo)
Erysipelas
Cellulitis
Necrotizing Fasciitis (Strep. Gangrene) –> toxin
Strep TSS –> toxin
Bacteremia

Question 5

Strep. pyogenes non-supprative disease

Answer 5

Rheumatic Fever (complication of Gp. A Strep pharyngitis (M protein I)

Acute glomerulonephritis (complication of Gp. A Strep infections)

Diagnose with ASO titer for Streptolysin O antibody

Question 6

Strep. agalactiae

Answer 6

G+c in chains
Gp. B beta hemolytic Strep.
Large colony, small zone of beta hemolysis

Most common cause of newborn meningitis and septicemia

Colonize lower GI, GU, and transient vaginal carriage

Question 7

Strep. agalactiae disease

Answer 7

Septicemia
Pneumonia
Meningitis

Newborns and puerperal sepsis

Question 8

Strep. pneumoniae

Answer 8

G+c lancet-shaped in pairs or short chains
Decolorize with age
Autolyse with age

Alpha hemolytic (pneumolysin breaks down hemoglobin –> green)

Fastidious
Virulence –> encapsulated (smooth) strains
Mucoid colonies

Treat with penicillin

Question 9

Strep. pneumoniae diseases

Answer 9

Pneumonia
Meningitis
Bacteremia
Sinusitis
Otitis media