Pulmonary Infections

Question 1

What is a key physical sign in pneumonia, and what causes it? Give the general mechanism & specific mediators.

Answer 1

Pleuritic chest pain - breathing in expands lungs, stretching pleura, which is sensitized to pain mediators (i.e., bradykinin and PGE2)

Question 2

Name the 3 types of pneumonia and distinguish how each appears on x-ray.

Answer 2

(1) Lobar: consolidation takes over entire lung (2) Bronchopneumonia: consolidation along small airways, patchy (3) Interstitial: inflammation along interstitium (connective tissue of alveolar sacs), increase in lung markings

Question 3

Which types of pneumonia are typically due to bacterial versus viral infections?

Answer 3

BACTERIAL: Lobar, bronchopneumonia; VIRAL: Interstitial (aka atypical)

Question 4

What is most common cause of lobar pneumonia? What is another important cause?

Answer 4

Streptococcus pneumoniae; Klebsiella pneumoniae

Question 5

How does resolution of lobar pneumonia occur?

Answer 5

Type II pneumocytes are stem cells that regenerate lining of alveolar lung sacs

Question 6

What is another name for interstitial pneumonia, and why?

Answer 6

Atypical - atypical presentation: relatively mild upper respiratory symptoms (minimal sputum and low fever)

Question 7

What 3 bacteria are associated with aspiration pneumonia?

Answer 7

Anaerobic bacteria in oropharynx: Bacteroides, Fusobacterium, Peptococcus

Question 8

What is the most common cause of community-acquired pneumonia? With what kind of pneumonia is it associated?

Answer 8

Streptococcus pneumoniae; Lobar pneumonia

Question 9

What 3 patient populations are most affected by Klebsiella pneumoniae?

Answer 9

Malnourished and debilitated individuals, especially (1) elderly in nursing homes (2) alcoholics (3) diabetes

Question 10

What is the most characteristic physical finding of K. pneumoniae, and what causes this?

Answer 10

Red currant jelly sputum due to thick mucoid capsule

Question 11

What often complicates K. pneumoniae pneumonia?

Answer 11

Abscess

Question 12

What is the most commonly cause of secondary pneumonia? With what kind of pneumonia is it associated?

Answer 12

Staphylococcus aureus; Bronchopneumonia

Question 13

What are 2 complications common in S. aureus pneumonia?

Answer 13

(1) Abscess (2) Empyema (pus in pleural space)

Question 14

Besides S. aureus, what is another common cause of secondary pneumonia? In what other setting does it cause pneumonia?

Answer 14

Haemophilus influenze; pneumonia superimposed on COPD

Question 15

In what patient population does Pseudomonas aeruginosa commonly cause pneumonia?

Answer 15

Cystic fibrosis patients

Question 16

Besides H. influenzae, what are 2 causes of community-acquired pneumonia that also cause pneumonia superimposed on COPD?

Answer 16

Moraxella catarrhalis; Legionella pneumophila

Question 17

Besides COPD patients, in what other patient population does Legionella pneumophila cause pneumonia?

Answer 17

Immunocompromised

Question 18

How is Legionella pneumophila transmitted?

Answer 18

Water source

Question 19

What kind of organism is Legionella pneumophila, and how is it best visualized due to this characteristic?

Answer 19

Intracellular organism; Silver stain

Question 20

What is the most common cause of atypical pneumonia?

Answer 20

Mycoplasma pneumoniae

Question 21

What patient population does M. pneumoniae usually affect? Give 2 classic examples.

Answer 21

Young adults (e.g., military recruits or college students living in a dormitory)

Question 22

What is an important complication of M. pneumoniae pneumonia?

Answer 22

Autoimmune hemolytic anemia (IgM against I antigen on RBCs cause cold hemolytic anemia)

Question 23

How does M. pneumoniae appear on gram stain, and why?

Answer 23

Not visible on gram stain due to lack of cell wall

Question 24

What is the second most common cause of atypical pneumonia in young adults? Again, what is the first?

Answer 24

Chlamydia pneumoniae; M. pneumoniae

Question 25

In what context does CMV cause atypical pneumonia?

Answer 25

Posttransplant immunosuppressive therapy

Question 26

What are 3 patient populations in which Influenza virus causes atypical pneumonia?

Answer 26

(1) Elderly (2) Immunocompromised (3) Preexisting lung disease

Question 27

For what does pneumonia due to influenza virus increase the risk? Why is this important?

Answer 27

Increases risk for superimposed S. aureus or H. influenzae bacterial pneumonia; Most patients with flu virus do not die from virus itself, instead virus weakens immune system allowing secondary pneumonia to kill them

Question 28

What kind of pneumonia does Coxiella burnetii cause? What is its characteristic presentation? What is the name for this?

Answer 28

Atypical pneumonia; high fever (Q fever)

Question 29

In what 2 patient populations is atypical pneumonia due to Coxiella burnetii seen?

Answer 29

(1) Farms (2) Veterinarians (Coxiella spores are deposited on cattle by ticks or are present in cattle placentas)

Question 30

To what group of bacteria does Coxiella belong? In what 3 ways is it distinct from this group?

Answer 30

Rickettsial organism; (1) causes pneumonia (2) not require arthropod vector for transmission (survives as highly heat-resistant endospores) (3) not produce skin rash

Question 31

How does aspiration pneumonia present, and why?

Answer 31

Right lower lobe abscess; Right main stem bronchus branches at a less acute angle than the left

Question 32

What are 4 common sites/conditions of systemic spread of Tb?

Answer 32

(1) Meninges (meningitis) (2) Cervical lymph nodes (3) Kidneys (sterile pyuria) (4) Lumbar vertebrae (Pott disease)

Question 33

To where in the CNS does Tb spread? Be specific.

Answer 33

Meninges at base of brain