Streptococcus Species Flashcards
Describe the metabolic profile of Streptococcus pyogenes (Group A).
- Catalase activity
- Aerobicity
- Hemolytic activity
- Catalase-negative
- Microaerophilic
- Beta-hemolytic
What enzymes allow for the Beta-hemolysis of *Streptococcus pyogenes *(Group A)?
What is each’s oxygen lability and antigenicity?
- Streptolysin O: Oxygen labile – Antigenic
- Streptolysin-S: Oxygen stable – Non-antigenic
What “Group” is Strep. pyogenes?
Group A
What elements create the virulence of Strep. pyogenes?
- M-like surface proteins
- Lipotechoic acid
- Streptokinase production
- Hyaluronidase production
- DNAase production
- Anti-C5a peptidases
What is the function of M-like proteins of Strep. pyogenes?
- Blocks complement
- Binds Fc fragment of antibodies
- Adherence
- Assists with invasion
What is the function of Lipotechoic acid in S. pyogenes?
It is an adherence factor
- What is the function of the Hyaluronic acid capsule in S. pyogenes?
- What is the function of C5a peptidase in S. pyogenes?
- It assists with avoidance of opsonization
- It degrades C5a and prevents chemotaxis
- What is the function of Streptokinase in S. pyogenes?
- What is the function of DNAases in S. pyogenes?
- It cleaves plasminogen, fibrin, and fibrinogen
- It depolymerizes DNA from lysed cells
What are the toxins associated with Strep. pyogenes (_G_roup A _S_trep)?
What are they associated with?
- Erythrogenic/Pyogenic Toxin – Responsible for Scarlet fever
- Toxic shock syndrome toxin (similar to but different than Staph TSST-1) – Responsible for Strep Toxic Shock
What are the common traits for all Streptococcus species?
- **Gram + cocci **in pairs or chains
- Facultative anaerobes
- Oxidase positive
- Catalase negative
What illnesses can result from direct invasion/toxin of Streptococcus pyogenes (GAS)?
- Pharyngitis
- Skin infection: Cellulitis/Folliculitis/Impetigo/Nec Fasc
- Scarlet fever
- Toxic Shock Syndrom
What antibody mediated illnesses can occur from *Streptococcus pyogenes *(GAS) infection?
What symptoms are present for each?
- Rheumatic fever: myocarditis, migratory polyarthritis, chorea, rash, heart valve damage (10-20yrs)
- Acute Glomerulonephritis: tea colored urine following strep skin or pharynx infection.
What is the best treatment for Strep pyogenes infections?
Penicillin G
Penicillin V
Cephalosporin or Macrolide for Pen. allergies
IV Penicillin + Protein synthesis inhibitor (Clinda) for invasive/systemic infections
- What does the Gram stain microscopy look like for S. pyogenes?
- What is diagnostic for S. pyogenes on culture?
- What is the limitation of Rapid Strep swab?
- Gram positive cocci in chains
- It is the only beta-hemolytic strep sensitive to bacitracin.
- It is only a positive or negative for S. pyogenes (GAS)
What is the Lancefield group for Strep. agalactiae?
Group B
What is the metabolic profile of Group B Strep. agalactiae?
Catalase activity
Aerobic activity
Hemolytic activity
Bacitracin sensitivity on culture
Catalase negative
Facultative anaerobe
_Beta-hemolytic
Bacitracin resistant_
- What are the most common illnesses associated with Streptococcus agalactiae (GBS)?
- How is GBS menigitis diagnosed?
- What is the treatment for Group B Strep infection?
- Neonatal meningitis/pneumonia/sepsis
Sepsis in pregnant women - Gram stain and culture of CSF
- Penicillin G
What is the metabolic profile of Streptococcus pneumoniae?
Catalase activity
Aerobic activity
Hemolytic activity
- Catalase negative
- Facultative anaerobe
- Alpha-hemolytic
- What is Streptococcus pneumoniae’s primary virulence characteristic?
- What is a secondary virulence trait?
- It’s capsule has a very strong resistance to phagocytosis
- It’s toxic cell wall activates IL-1 and TNF-alpha and an intense inflammatory reaction.
What are the 4 primary illnesses produced by S. pneumoniae?
- Pneumonia
- Meningitis
- Sepsis
- Otitis media
- What would a gram stain of S. pneumoniae reveal?
- What is *S. pneumoniae *sensitive to on culture?
- What does a Quellung reaction detect?
- Gram positive diplococci
- Optochin sensitive
- Presence of a capsule
- How does the pneumovax vaccine work?
- What is the treatment for S. pneumoniae?
- It is an anti-capsular antibody vaccine of 23/83 polysaccharides. There is a 13 valent vaccine for children less than 2.
- Penicillin G (IM) or
Erythro/Azythromycin and Ceftriaxone
What serious illness might an individual have if they culture positive for Streptococcus bovis?
Gastrointestinal cancer