Streptococci
Morphology
- Gram Positive Cocci
- Arranged in chains
- Think Streptococcus throat like necklace
- May elaborate capsular polysaccharide that impedes phagocytosis » Slime
- Pili project from capsule
Classification
- ß-Haemolytic
- Produce Haemolysins
- Group A
- Streptococcus pyogenes
- Majority of pathogens
- Group B (B = Baby)
- Streptococcus agalactinae
- Normal flora of female genital tract
- Important in neonatal infections
- Group G (G = Gut)
- Normal enteric flora
- Enterococcus
- Streptococcus faecalis
- Streptococcus faecium
- Normal enteric flora
- Non-ß-Haemolytic
- Streptococcus pneumoniae
- Cause pneumonia
- Streptococcus Viridans
- Normal respiratory flora
- Peptostreptococci
- Gut Anaerobes
- Streptococcus pneumoniae
Toxins/ Enzymes
- Haemolysins
- Haemolyse RBC
- Incomplete disruption - Alpha haemolysis
- Complete disruption - Beta haemolysis
- Group A - ß-Haemolytic Strep produce
- Streptolysin O
- Streptolysin S
- Streptolysin O
- Haemolyse RBC
- Streptokinase
- Converts Plasma Plasminogen to Plasmin
- Proteolytic enzyme that digests fibrin
- Hyaluronidase
- Splits Hyaluronic acid
- Aids in spreading infection
- Erythrogenic Toxin
- Causes rash of Scarlet Fever
Pathology
- ß-Haemolytic Streptococcus
- Commonly cause
- Erysipelas
- Strep Throat
- Impetigo
- Infective Endocarditis (SBE)
- Rheumatic Fever
- Acute Glomerulonephritis
Treatment
- All sensitive to Penicillin G
Webpage Last Modified: 27 January, 2010
