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28 Cards in this Set
- Front
- Back
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pneumococcus is an
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a-hemolytic streptococcus
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inhibits effective host clearance functions involving complement and antibody-mediated phagocytosis
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thick layer of surface polysaccharide
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energy metabolism of pneumococcus
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purely fermentative
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pneumococcus lacks catalase, therefore generating copious amounts of
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hydrogen peroxide
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cholesterol-dependent toxin accounting for much of its ability to damage host tissues
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pneumolysin
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imparts a smooth appearance to the colonies on agar
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capsule
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degrades its own cell wall
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autolysin
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obscures the underlying components of the bacterial cell surface
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capsule
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Quellung reaction
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addition of an antibody that causes an antigen-antibody precipitation in the normally transparent zone occupied by the capsule
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seasons when pneumococcal infections occur
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winter and early spring
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reservoir of S. pneumoniae
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humans
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fraction of preschool children who carry pneumococci
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2/3
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first stage of the inflammatory process
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alveoli fill with serous fluid containing many organisms but few inflammatory cells
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spreading of infection into adjacent alveoli occur through
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pores of Kohn
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second stage of inflammatory process
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early consolidation- alveoli infiltrated with neutrophils and red blood cells
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acute phase reactant that binds to the bacterial surface leading to activation of the complement cascade
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C-reactive protein
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third stage of pneumococcal pneumonia
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late consolidation- alveoli packed with neutrophils, only a few remaining pneumococci
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fourth stage of pneumococcal infection
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resolution- neutrophils are replaced by scavenging macrophages
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most common local complication of pneumococcal pneumonia
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pleural effusion
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infection of the pleural space
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empyema
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fulminant, rapidly progressive pneumococcal bacteremia can occur in patients with
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asplenia (either due to splenectomy or sickle cell)
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# of lancet-shaped gram-positive diplococci per oil field when diagnosis of pneumococcal pneumonia is likely
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>10
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on blood agar, pneumococcal colonies are surrounded by
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a-hemolysis (a green-brownish discoloration caused by hydrogen peroxide production)
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reason for short term effect of increased inflammation after antibiotic administration
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lysis of pneumococcal cells releases breakdown products that increase inflammation
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mechanism for pneumococci antibiotic resistance
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altered penicillin-binding proteins (NOT b-lactamase as in staphlococci)
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taking up and integrating DNA found in the environment
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transformation
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reason patients with Hodgkin disease or multiple myeloma do not respond to pneumococcal vaccine
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they do not make an adequate antibody response to the vaccine
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type of pneumococcal vaccine to be used in children
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pneumococcal conjugate vaccine (they respond poorly to polysaccharide vaccines)
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