Atypical Pneumonia Flashcards
Describe mycoplasma pneumoniae
- no cell wall
- bacterial membrane contains sterols for stability
Mycoplasma pneumoniae is the classic cause of ____
walking pneumonia
Mycoplasma pneumoniae is the most common cause of pneumonia in what population
school-aged children (also common in prison and military recruits-aka groups in close quarters)
Pathogenesis of Mycoplasma pneumoniae
adhesion binds to ciliated epithelial cells and causes reduced ciliary clearance
How does Mycoplasma pneumoniae present?
-insidious onset of dry cough, headache, low-grade fever, myalgia, and sore throat
How is Mycoplasma pneumoniae diagnosed?
- serology (not great)
- PCR from respiratory secretions
- cold agglutinins
- growth on Eaton agar
Note on Cold agglutinins and Mycoplasma pneumoniae
IgM autoantibodies against type O RBCS that agglutinate the cells at 4C but not 27C. Half of patients with Mycoplasma pneumoniae will be positive
How is Mycoplasma pneumoniae treated?
-macrolide, doxycycline, or fluorquinolone
What other manifestations can Mycoplasma pneumoniae produce?
- hemolysis
- Rash
- CNS involvement
- CV involvement (CHF, myocarditis, etc.)
What type of CNS involvement is most common in Mycoplasma pneumoniae?
encephalitis
Describe Chylamydia (Clamydophila pneumoniae)
obligate intracellular organism that is the 2nd most common cause of atypical pneumonia
How does the patient population of Clamydophila pneumoniae compare to mycoplasma?
older adults in Clamydophila pneumoniae
How is Clamydophila pneumoniae treated?
doxycycline
no good diagnostic test
Describe Legionella pneumophila
gram negative rod, facultative intracellular
Pathogenesis of Legionella pneumophila
- avoids phagolysosome fusion and replicates within alveolar macrophages
- endotoxin
How is Legionella pneumophila contracted?
aerosol transmission from environmental source habitat (AC systems etc.)
What patient population is common in Legionella pneumophila infection?
- older
- smokers
- alcoholics
Clinically, Legionella pneumophila causes what two diseases?
- Legionnaire’s disease
- Pontiac fever
How does Legionnaire’s disease present?
severe pneumonia with dry cough, fever, diarrhea, and confusion
How does Pontiac disease present?
mild flu-like syndrome
What does a gram stain of Legionella pneumophila show?
neutrophils and macrophages but no organisms (need a silver stain)
Labs in Legionella pneumophila infection will show what?
hyponatremia
What does Legionella pneumophila grow well on?
charcoal yeast extract culture with iron and cysteine
Treatment of Legionella pneumophila
Macrolide (Azithro) or Levofloxacin
