Medical Microbiology 850
Quiz 5 ANSWERS (10 points) - 10/20/00
CASE 5: Community Acquired Bacterial Pneumonia
Dolores Furtado, Ph.D.
1. (2 pts) A. What is coiling phagocytosis?
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Coiling phagocytosis is when the macrophage extends a long pseudopod
that circles around the adherent L. pneumophila organisms to create a phagosome.
B. How do Legionella pneumophila evade killing after phagocytosis?
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Organism surface proteins prevent phagolysosomal fusion and acidification
of the phagosome.
2. (2 pts) List two likely reasons why PneumoVax immunization failed to
prevent pneumonia in the patient with the splenectomy.
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A serotype other than 23 contained in the vaccine caused the infection.
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Infection by one of the serotypes in the vaccine: immunization did not
result in production of protective antibody.
3. (3 pts) Compare the pathogenesis of tuberculosis infection in an immunocompetent
person to the pathogenesis of tuberculosis infection in a person whose
cell medicated immunity is moderately impaired.
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Immunocompetent person: Infection is asymptomatic (primary complex)
and is detected by PPD skin test conversion.
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Immunocompromised person: Infection progresses to disease (symptomatic)
until CMI is triggered. More extensive damage (immunopathology) is likely.
How do organisms get to the apical regions of the lungs in persons who
develop disease?
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Lympho-hematogenous spread
4. (3 pts) Name the means by which humans are most likely to become exposed
to:
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Legionella pneumophila: Water in environment; air conditioners etc.
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Streptococcus pneumoniae: Aerosolized droplets (infected personcoughs)
that are recently inhaled or have colonized the throat
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Mycobacterium tuberculosis: Aerosolized droplets (infected person coughs)
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