WEEK 5: STREPTOCOCCI Flashcards
- Complete lysis of RBC’s around colony
- **Clear area **around colony
BETA
- Partial lysis of RBC’s around colony
- Greenish discoloration of area around colony
ALPHA
- No lysis of RBC’s around colony
- No change in agar
GAMMA
Small area of intact RBC around colony surrounded by a wider zone of complete hemolysis
ALPHA PRIME
i. Gram (+) cocci arranged in pairs or chains
ii. Facultative anaerobe but some are aerotolerant anaerobes
iii. Some are capnophilic
iv. Non-motile; (-) catalase, oxidase and gas production
Streptococci
Negative in Catalase test
Streptococci
test the ability of the organism to
breakdown of H2O2 into oxygen and water
Catalase Test
organisms that are positive in catalase test
Staphylococcus & Micrococcus
in catalase test, copious bubble form if the organism is?
Positive
No or few bubbles
Negative in Catalase test
What is being extracted in Lancefield Classification?
C Carbohydrate
Group A strep
S. pyogenes
Group B strep
S. agalactiae
Group C strep
S. dysgalactiae, S. equisimilis
Group D Non enterococcus
S. bovis group / S. gallolyticus
Group D Enterococcus
E. faecalis, E. faecium
Pneumococcus
S. pneumoniae
Which of the species under Streptococci group does not have a Lancefield Classification?
S. pneumoniae
Viridans strep (A, C, F, G, N)
S. anginosus, mutans, mitis
What is the hemolytic pattern of Group A strep? (S. pyogenes)
β (beta)
What is the hemolytic pattern of Group B strep? (S. agalactiae)
β (beta)
What is the hemolytic pattern of Group C strep? (S. dysaglactiae, S. equisimilis)
β (beta)
What is the hemolytic pattern of Group D Non enterococcus? (S. bovis group)
α,γ (alpha, gamma)
What is the hemolytic pattern of Group D Enterococcus? (E. faecalis, E. faecium)
α,β,γ (alpha, beta, gamma)
What is the hemolytic pattern of Pneumococcus? (S. pneumoniae)
α (alpha)
What is the hemolytic pattern of Viridans strep? (Anginosus, mutans, mitis)
β, α, γ (beta, alpha, gamma)
- Grows at 37C
- Mostly has β-hemolytic reactions
- S. pyogenes, group C and G streptococci
Pyogenic group
- Grows at 37C and 45C
- indigenous microbiota in the URT
- S. mutans, S. mitis and S. salivarius
Viridans group
- Grows at 10C and 37C
- found on dairy products
- S. lactis
Lactic group
- Grows at 10C, 37C and 45C
- part of the indigenous microbiota of the human intestine
- E. faecalis
Enterococcus group
Attached to the peptidoglycan
Antiphagocytic
For adherence to mucosal cells
Primary
M Protein
Mediates adherence to host epithelial cells
Protein F (Fibronectin-binding protein)
Mediates attachment to mucosal cells
Lipoteichoic acid
Prevents opsonized phagocytosis
Mask bacterial antigens
Hyaluronic acid Capsule
Group of four enzymes with nuclease activity
Degrade host DNA (DNase) and RNA
Streptodornase (DNases)
Subsurface hemolysin (Oxygen labile)
Toxic to RBC’s, WBC’s and platelets
Induces antibody response - anti-streptolysin O
Streptolysin O
Surface hemolysin (Oxygen stable)
Lysis WBC’s and is non immunogenic
Streptolysin S
Causes lysis of fibrin clots
Streptokinase (Fibrinolysin)
Solubilizes hyaluronic acid in connective tissues
Hyaluronidase
Exotoxins are associated with Scarlet Fever and Streptococcal Toxic shock-like syndrome
Streptococcal pyrogenic exotoxins A, B, C (SPE)
Spreading-factor enzyme
Hyaluronidase
Suppurative fasciitis, hospital
gangrene, necrotizing erysipelas
Invasive infection characterized by
inflammation and necrosis of skin,
subcutaneous fat and fascia
Necrotizing Fasciitis
superficial and localized
Impetigo
involves deeper tissue invasion
Cellulitis
acute spreading erythematous lesion
Erysipelas
Two types of Post-Streptococcal Sequelae
Rheumatic Heart Fever and Acute glomerulonephrits (AGN)
diffuse red rashes (chest to extremities)
Scarlet Fever
Condition wherein organ system
shuts down leading to death
Streptococcal Toxic Shock Syndrome
what organism causes these clinical Infections?
- Bacterial Pharyngitis and Tonsilitis
- Pyodermal Infections
- Necrotizing Fascitis
- Streptococcal Toxic Shock Syndrome
- Post-Streptococcal Sequelae
Streptococcus pyogenes