Streptococcus Flashcards
Consist pf a large family of medically important species, including Streptococcus spp. and Enterococcus spp.
Streptococcaceae
Facultative anaerobes.
Streptococcus
Some species are capnophilic.
Streptococcus
Growth is enriched on media containing blood or serum.
Streptococcus
Hemolyze red blood cells in vitro in varying degrees.
Hemolysis
[4] Hemolysis
- β hemolysis
- α hemolysis
- non-hemolytic
- Alpha-prime (α′) or wide zone hemolysis
Complete disruption of erythrocytes with clearing of the blood around the bacterial growth.
[hemolysis]
β hemolysis
Incomplete lysis of erythrocytes with reduction of hemoglobin and the formation of green pigment.
[hemolysis]
α hemolysis
Sometimes called gamma hemolysis.
[hemolysis]
Non-hemolytic
The colonies are surrounded by a very small zone of no hemolysis and then a wider zone of β-hemolysis: Viridans group.
[hemolysis]
Alpha-prime (α′) or wide zone hemolysis
It cause res spreading rash: scarlet fever; caused by streptococcal pyrogenic exotoxins, formerly called erythrogenic toxins.
S. pyogenes
Caused by streptococcal pyrogenic exotoxins, formerly called erythrogenic toxins.
Scarlet fever
It resist phagocytosis and adheres bacterial cell to mucosal cells.
M protein
Attachment of streptococci to the oral mucosal cells.
Fibronectin binding
It is weekly immunogenic
Hyaluronic acid capsule
It is acid-labile and hea-labile.
T substance
Strep throat
Pharyngitis
Pyodermal infections
Impetigo, Erysipelas, and Cellulitis
“Flesh eating bacteria”: infection tends to disseminate into deeper tissues: categorized as type 1, 2, or 3
Necrotizing Fascilitis
