Etiology/Epidemiology

Question 1

What is the annual incidence of pneumonia in those older than 65? Older than 85?

Answer 1

About one in fifty and one in twenty, respectively.

Question 2

Leading causes of community-aquired pneumonia.

Answer 2

Strep pneumoniae, H. influenza, Mycoplasma and Chlamydophila pneumoniae

Question 3

Leading causes of acute pneumonia.

Answer 3

S. pneumoniae, H influenza, other GN bacilli, Legionella spp, Chlamydophila pneumoiae, Mycoplasma, Staph aureus, Influenza A + B, Parainfluenza, RSV, Anaerobes

Question 4

Key points about the protective mechanisms of the lung.

Answer 4

1. Normally, the tracheobronchial tree is sterile
2. The nasal turbinates trade foreign particles and the epiglottis covers the trachea.
3. Mucin has antibacterial activity, and cilia transport mucin out of the lung.
4. Coughing expels foreign material that enters the tracheobronchial tree.
5. Alveoli can deliver PMNs, macrophages, immunoglobulins, and complement to destroy invading pathogens.
6. Lymphatics drain macrophages and PMNs to the mediastinal lymph nodes

Question 5

Key points about the pathogenesis of pneumonia

Answer 5

1. Pathogens are aspirated or inhaled as small aerosolized droplets.
2. Bacterial invasion of the alveoli induces edema fluid that spreads to other alveoli through the pores of Kohn, and infiltration by PMNs and RBCs, followed by macrophages.
3. Infection spreads centrifugally
4. Streptococcal pneumonia does not cause permanent tissue destruction.
5. Staphylococcus aureus, GN rods, and anaerobes cause permanent damage.

Question 6

What are factors that predispose to pneumonia?

Answer 6

1. Viral infections damage cilia and produce serous exudate that can transport nasopharyngeal bacteria into the alveoli.
2. Smoking damages bronchial epithelial cells and impairs ciliary function.
3. Alcohol and other drugs depress coughing and epiglottal function
4. Elderly patients have reduced humoral and cell-mediated immunity, and may have impaired swallowing because of stroke.
5. Patients on immunosupressives or AIDS have depressed humoral and cell-mediated immunity.
6. Patients with chronic diseases are at increased risk of pneumonia.
7. Cold-weather dries the mucous membranes and increases person-to-person infection.

Question 7

What is acute pneumonia?

Answer 7

Develops in 24-48 hours

Question 8

What is subacute pneumonia?

Answer 8

Develops over 3 days to one week

Question 9

What is chronic pneumonia?

Answer 9

Symptoms progress over three weeks to several months

Question 10

What is typical pneumonia?

Answer 10

Characterized by the more rapid onset of symptoms, more severe symptoms, productive cough and dense consolidation on CXR

Question 11

What is an atypical pneumonia?

Answer 11

Slower onset, less severe symptoms, non-productive cough and patchy interstitial pattern on CXR

Question 12

How is CAP defined?

Answer 12

Patient not recently (>14 days) in a hospital or chronic care facility.

Question 13

Classic symptoms seen in Strep pneumonia.

Answer 13

Rusty-colored sputum, rigor, pleuritic chest pain

Question 14

Classic symptoms seen in H influenza.

Answer 14

More gradual onset, seen in smokers with COPD

Question 15

Classic symptoms seen in Staph aureus.

Answer 15

Follows influenza pneumonia, rapidly progressive acute disease.

Question 16

Classic symptoms seen in Legionella.

Answer 16

Nonproductive cough, GI symptoms, confusion.

Question 17

What are risk factors for pseudomonas?

Answer 17

Endotracheal intubation, immunosuppression, steroid use and recent antibiotic use