Atypical Pneumonia

Question 1

Describe mycoplasma pneumoniae

Answer 1

• no cell wall

- bacterial membrane contains sterols for stability

Question 2

Mycoplasma pneumoniae is the classic cause of ____

Answer 2

walking pneumonia

Question 3

Mycoplasma pneumoniae is the most common cause of pneumonia in what population

Answer 3

school-aged children (also common in prison and military recruits-aka groups in close quarters)

Question 4

Pathogenesis of Mycoplasma pneumoniae

Answer 4

adhesion binds to ciliated epithelial cells and causes reduced ciliary clearance

Question 5

How does Mycoplasma pneumoniae present?

Answer 5

-insidious onset of dry cough, headache, low-grade fever, myalgia, and sore throat

Question 6

How is Mycoplasma pneumoniae diagnosed?

Answer 6

• serology (not great)
• PCR from respiratory secretions
• cold agglutinins
• growth on Eaton agar

Question 7

Note on Cold agglutinins and Mycoplasma pneumoniae

Answer 7

IgM autoantibodies against type O RBCS that agglutinate the cells at 4C but not 27C. Half of patients with Mycoplasma pneumoniae will be positive

Question 8

How is Mycoplasma pneumoniae treated?

Answer 8

-macrolide, doxycycline, or fluorquinolone

Question 9

What other manifestations can Mycoplasma pneumoniae produce?

Answer 9

• hemolysis
• Rash
• CNS involvement
• CV involvement (CHF, myocarditis, etc.)

Question 10

What type of CNS involvement is most common in Mycoplasma pneumoniae?

Answer 10

encephalitis

Question 11

Describe Chylamydia (Clamydophila pneumoniae)

Answer 11

obligate intracellular organism that is the 2nd most common cause of atypical pneumonia

Question 12

How does the patient population of Clamydophila pneumoniae compare to mycoplasma?

Answer 12

older adults in Clamydophila pneumoniae

Question 13

How is Clamydophila pneumoniae treated?

Answer 13

doxycycline

no good diagnostic test

Question 14

Describe Legionella pneumophila

Answer 14

gram negative rod, facultative intracellular

Question 15

Pathogenesis of Legionella pneumophila

Answer 15

• avoids phagolysosome fusion and replicates within alveolar macrophages
• endotoxin

Question 16

How is Legionella pneumophila contracted?

Answer 16

aerosol transmission from environmental source habitat (AC systems etc.)

Question 17

What patient population is common in Legionella pneumophila infection?

Answer 17

• older
• smokers
• alcoholics

Question 18

Clinically, Legionella pneumophila causes what two diseases?

Answer 18

• Legionnaire’s disease

- Pontiac fever

Question 19

How does Legionnaire’s disease present?

Answer 19

severe pneumonia with dry cough, fever, diarrhea, and confusion

Question 20

How does Pontiac disease present?

Answer 20

mild flu-like syndrome

Question 21

What does a gram stain of Legionella pneumophila show?

Answer 21

neutrophils and macrophages but no organisms (need a silver stain)

Question 22

Labs in Legionella pneumophila infection will show what?

Answer 22

hyponatremia

Question 23

What does Legionella pneumophila grow well on?

Answer 23

charcoal yeast extract culture with iron and cysteine

Question 24

Treatment of Legionella pneumophila

Answer 24

Macrolide (Azithro) or Levofloxacin

Question 25

What is aspiration pneumonia?

Answer 25

aspiration of gastric contents

Question 26

What patient population commonly gets aspiration pneumonia?

Answer 26

debilitated or unconscious patients, or those with repeated vomiting (alcoholics)

Question 27

What is the common age for Chlamydophila pneumoniae?

Answer 27

This type of pneumonia can occur all year and often is mild. The infection is most common in people 65 to 79 years old but can be middle aged

Question 28

T or F. Most cases of viral pneumonia are mild.

Answer 28

T. They get better in about 1 to 3 weeks without treatment. Some cases are more serious and may require treatment in a hospital.

Question 29

PCP is common in which patients?

Answer 29

• Have HIV/AIDS or cancer
• Have had an organ transplant and/orblood and marrow stem cell transplant
• Take medicines that affect their immune systems