Streptococcus pneumoniae Flashcards
(41 cards)
Streptococcus pneumoniae (aka pneumococcus):
Shape Configuration Gram stain Catalase state Optochin susceptibility Solubility in bile salts
Round or rod-shaped Pairs or chains Gram + Catalase (-) Op susceptible Dissolve in bile salts
What type of pneumococcal disease is unchanged since pre-antibiotic era?
Age relationship invasive pneumococcal disease
What molecule traverses cell wall of streptococcus pneumoniae, allows bacteria to adhere to cells, interacts with TLR’s, and stimulates inflamm responses?
Lipoteichoic acid
What is alpha-hemolysin?
Toxin produced by pneumococcus - Breaks down hemoglobin on blood agar plates so they turn green
What is placed in middle of plate to identify Streptococcus pneumoniae?
Optochin disk – diffuses across agar – clear area around the optochin disk is where bacteria are killed
Name 4 diseases caused primarily by pneumococcus.
Pneumonia, otitis media, acute sinusitis, meningitis
What is the outermost layer of Strep pneumoniae? How does this help pneumococcus survive?
Polysaccharide capsule:
1) not recognized by receptors on PMNs
2) prevents PMN receptors from interacting with Fc of IgG (which can diffuse through capsule and bind cell wall)
What substances do Strep pneumoniae produce that cause disease by stimulating an intense inflammatory response?
Peptidoglycan and pneumolysin
Where in the body do pneumococci colonize? What part of population do they commonly spread through?
Nasopharynx - kids
T or F. Pneumococci extensively damage tissues by releasing lots of toxins and enzymes.
FALSE - primarily causes disease by inducing an inflammatory response and interfering with normal clearance mechanisms
In general, why is antibody ineffective against gram + bacteria?
The thickness of the cell wall
Association with what additional type of infection is associated with pneumococcus? How does it interfere with normal clearance mechanisms?
Viral - damages ciliary activity, increases mucous secretions, causes edema
What toxin do streptococci produce that makes the colonies collapse in the center and self-destruct in vitro? What does it do in vivo?
Autolysin
In vivo - causes inflammation and damages tissues
What is the definitive identification for pneumococcus?
If colonies dissolve in bile salts
Immunologic differences in _____ ______ is the basis for distinguishing 93 pneumococcal serotypes.
capsular polysaccharides
What is serotyping?
Use of Ab present in serum to distinguish among isolates of a single species
Which TLR does lipoteichoic acid primarily interact with?
What unique substances does it contain?
What protein produced by liver in inflammatory diseases/infections reacts with this substance?
TLR2»» TLR4
Choline-rich C-polysaccharide - important proteins that render pneumococcus virulent attach to this choline
C reactive protein
What proteins are being studied as possible replacements for capsular polysaccharide vaccines?
Choline-binding proteins - antibodies against these may enable phagocytosis
What is the best studied choline-binding protein and what might its function be?
PspA - pneumococcal surface protein A
Anti-phagocytic function
What virulence factor produced by pneumococci activates complement, damages ciliated cells, and reproduces changes of pneumonia?
Pneumolysin
How is pneumococcus spread?
Close contact - intimate facial contact, hand to hand, aerosol (sneezing, coughing)
What must bacteria first adhere to to cause disease? What do pneumococci specifically use for this adhesion?
Epithelial cells
Use lipoteichoic acid
When bacteria are present in sufficient number to be cultured and if they cause no symptoms or signs of infection, we call this _____
Colonization
T or F. If an organism has caused an infection, it has also colonized.
FALSE - some organisms like Mycobacterium tuberculosis or Treponema pallidum NEVER colonize - their presence only indicates infection.
