Streptococcus Pyogenes

Question 1

Type

Answer 1

Gram+ cocci
- Catalase
Negative
- Nonmotile
-facultative
Anaerobe
-Lancefield Group
A
- B hemolysis
producing
Streptolysin S
- Sensitive to
Bacitracin
- SOD
(aerotolerant)
- growth
enhanced by CO2

Question 2

Transmission
& season

Answer 2

Human throat
Direct contact,
respiratory
droplets

Question 3

Presentation

Answer 3

1.supurative
2.scarlet fever
3.non suppurative

Question 4

Suppurative presentation

Answer 4

Pharyngitis, skin & soft
tissue infection, sepsis,
rheumatic fever, acute
glomerulonephritis
● Induces pus due to
leukocidin

Question 5

scarlet fever

Answer 5

pharyngitis
sequelae; diffuse
erythematous rash beginning
on chest & spreading to
extremities, strawberry
tongue

Question 6

non -suppurative

Answer 6

1.rheumatic fever
2.acute PSGN

Question 7

Rheumatic fever

Answer 7

(leading to
rheumatic heart disease)-
Antecedent
pharyngitis*preventable by
penicillin prophylaxis
Predominant featuresis joint sx in adults
Predominant feature in
kids:heart sx

Question 8

Acute PSGN:

Answer 8

: strep
infection of skin(impetigo) or
throat(pharyngitis) →
inflammation of glomeruli -
hematuria, edema, HTN,
proteinuria

Question 9

Pathogenesis

Answer 9

A antigen: group specific carb
in cell wall
M protein: type specific in
CW-serotyping
- Anti-phagocytosis:
1. capsule(hyaluronic
acid),
2. C5a peptidase,
3. M and M-like proteins,
(also entry)
4. LTA,
5. F protein (adherence
to fibronectin)
- Adhere to & invade
cell wall: M protein,
LTA, F protein

Question 10

• Toxins:

Answer 10

1. Streptococcal
   pyrogenic
   exotoxins(SPE):fever
2. Streptolysin S - both S
   & O break down WBC
3. Streptolysin O
4. Streptokinase: break
   down fibrin
5. DNAse: break down
   nucleic acid

Question 11

Diagnostic

Answer 11

Clinical
specimens
-Lab growth
media: Normal
culture
medium=Blood
Agar(BA)
- Yeast
extract+peptone
+5% blood
- ASO
titers(Streptolys
in O)
-Anti-DNAse