Lesson 1: STREPTOCOCCUS Flashcards
Family Streptococcaceae 3 genera
Streptococcus
Enterococcus
Lactococcus
Catalase negative
Streptoccoci
Media used for Streptococci
BAP
CHOC
Todd-Hewitt Broth
Streptococci
Facultative anaerobes and needs ? CO2 for growth
5-10%
● Green discoloration
Alpha hemolytic
Organisms w A-hemolysis
S. pneumoniae
S. viridans
Clear or colorless zone of hemolysis surrounding bacterial colony
Beta hemolytic
Organisms w B-hemolysis
S. pyogenes
S. agalactiae
Non-hemolytic
Gamma hemolytic
Organisms w Gamma hemolysis
Enterococcus spp.
Physiologic divisions
Pyogenic division
Viridans division
Enterococcus division
Lactic division
Found in Sherman 1937
Bergey’s/Academic Classification
PHYSIOLOGIC DIVISION (Streptococci)
- streptococcal organisms = diseases associated w PUS FORMATION
Pyogenic division
PHYSIOLOGIC DIVISION (Streptococci)
Includes beta hemolytic strains
Pyogenic division
Lancefield groups
A, B, C, E, F, and G
PHYSIOLOGIC DIVISION (Streptococci)
Difference between Viridans and Enterococcus division
Viridans - not salt tolerant
Enterococcus - salt tolerant
PHYSIOLOGIC DIVISION (Streptococci)
● Not beta hemolytic
● Not salt tolerant
● Grow at high pH
Viridans division
PHYSIOLOGIC DIVISION (Streptococci)
● Salt tolerant
● Grow at high pH
Enterococcus division
PHYSIOLOGIC DIVISION (Streptococci)
Enterococcus division
Temp range
10C-45C (optimal growth temp)
PHYSIOLOGIC DIVISION (Streptococci)
● Not clinically significant
● Associated with dairy industry
Lactic division
Developed Lancefield Grouping
Rebecca Lancefield (1933)
Divides the Streptococci into serological groups; Based on antigenic properties of carbohydrate group antigens in their cell wall
Lancefield Grouping
Lancefield grouping
Clinically significant; Mostly isolated and associated with human infections
A, B, C, D, F, and G
Done to differentiate Streptococci into groups
Serological testing
Lancefield group A
S. pyogenes
Lancefield group B
S. agalactiae
Lancefield group C and G
S. dysgalactiae and S. equi
Lancefield group A, C, F, and G
S. anginosus
Not a normal flora
Most virulent for humans
GROUP A: STREPTOCOCCUS PYOGENES (GAS)
GAS Diseases
- Bacterial Pharyngitis
- Skin infections
- Invasive diseases
GAS Complications
Rheumatic heart disease
Acute glomerulonephritis
GAS transmission
- person to person contact
- aerosol droplets