Internal Medicine Exam Community-Acquired Pneumonia 3 — Questions and Answers
Question 1: A 55-year-old with alcoholism presents with right upper lobe pneumonia and foul-smelling sputum. What organism is the most likely cause?
- Streptococcus pneumoniae
- Haemophilus influenzae
- Anaerobes / aspiration flora (Correct answer)
- Legionella pneumophila
Correct answer: Anaerobes / aspiration flora
Aspiration pneumonia in alcoholics involves anaerobic organisms from the oropharynx and classically affects dependent lung segments with putrid sputum.
Question 2: Which radiographic pattern is MOST characteristic of Pneumocystis jirovecii pneumonia (PCP) in an immunocompromised host?
- Dense lobar consolidation
- Bilateral interstitial/perihilar infiltrates (Correct answer)
- Cavitary lesion with air-fluid level
- Pleural effusion with atelectasis
Correct answer: Bilateral interstitial/perihilar infiltrates
PCP classically presents with bilateral perihilar interstitial infiltrates on CXR, often with a ground-glass pattern on CT.
Question 3: A 70-year-old develops CAP. Blood cultures are ordered. According to IDSA guidelines, blood cultures are routinely recommended in which scenario?
- All outpatient CAP
- CAP requiring ICU admission (Correct answer)
- CAP in patients over 65
- All hospitalized CAP patients
Correct answer: CAP requiring ICU admission
Current IDSA guidelines recommend blood cultures primarily for severe CAP requiring ICU care, not for all hospitalized patients.
Question 4: Legionella urinary antigen testing detects which serogroup of Legionella pneumophila?
- All serogroups equally
- Serogroup 1 only (Correct answer)
- Serogroups 1 and 2
- Serogroup 6 only
Correct answer: Serogroup 1 only
The Legionella urinary antigen test detects only serogroup 1, which causes approximately 70–80% of Legionella pneumonia cases.
Question 5: Which clinical feature is MOST helpful in distinguishing Legionella pneumonia from pneumococcal pneumonia?
- Pleuritic chest pain
- High fever with rigors
- Hyponatremia + GI symptoms + elevated LFTs (Correct answer)
- Productive rusty sputum
Correct answer: Hyponatremia + GI symptoms + elevated LFTs
Legionella characteristically causes hyponatremia, diarrhea, abdominal pain, and transaminase elevation in addition to pneumonia.
Question 6: What is the appropriate duration of antibiotic therapy for uncomplicated, mild-to-moderate CAP that shows clinical improvement?
- 3 days
- 5 days (Correct answer)
- 10–14 days
- 21 days
Correct answer: 5 days
Current evidence supports 5-day courses for uncomplicated CAP in patients who show clinical stability by day 3.
Question 7: A 65-year-old with CAP and no comorbidities is treated as an outpatient. Which antibiotic is appropriate as monotherapy?
- Amoxicillin-clavulanate
- Azithromycin (if low macrolide resistance) (Correct answer)
- Ceftriaxone IV
- Levofloxacin plus amoxicillin
Correct answer: Azithromycin (if low macrolide resistance)
Azithromycin monotherapy is appropriate for outpatient CAP in healthy patients without comorbidities in areas with low macrolide resistance (<25%).
Internal Medicine Exam Community-Acquired Pneumonia 3
A 55-year-old with alcoholism presents with right upper lobe pneumonia and foul-smelling sputum.
What organism is the most likely cause?