SESIÓN 11 STREPTOCOCCUS. Flashcards
Describe the Streptococcus.
- G (+), arranged in pairs or chains, most are facultative anaerobes, and some are capnophilic, catalase-negative. Growth is optimal on enriched blood agar media but is inhibited if the medium contains a high concentration of glucose.
What type of hemolysis does S. pyogenes have?
- Beta
How is S. pyogenes is transmitted?
- Direc t contact, respiratory droplets
In what grouping does S. pyogenes is in?
- Group A
What are the 3 different, overlapping schemes used to classify the Streptococcus organism?
- Group-specific carbohydrate (Lancefield groupings), hemolytic patterns, and biochemical (physiologic) properties.
How can we serotype S. Pneumoniae?
- Via capsule
How can we serotype S. pyogenes?
- Via M protein
What determines the virulence of group A Streptococci?
- By the ability of the bacteria to avoid opsonization and phagocytosis, adhere to the surface of host cells, and produce a variety of toxins and enzymes.
What helps S. pyogenes invade into epithelial cells?
- Process mediated by M protein and F protein.
Which toxin of S. pyogenes is responsible for the beta-hemolysis seen on blood agar?
- Streptolysin S
Where are S. pyogenes located?
- Transient colonization in upper respiratory tract and skin surface.
What are the suppurative diseases that S. pyogenes can cause? (7)
- Pharyngitis, Scarlet Fever, Pyoderma, Erysipelas, Cellulitis, Nectrotizing fasciitis, Streptococcal toxic shock syndrome.
What are the nonsuppurative diseases that S. pyogenes can cause? (2)
- Rheumatic fever and acute glomerulonephritis
Which type of M-protein in S. pyogenes is responsable for glomerulonephritis?
- M12
What is the treatment for S. pyogenes?
- Penicillin: oral cephalosporin or vancomycin.
