Internal Medicine Exam Community-Acquired Pneumonia 2 — Questions and Answers
Question 1: A 68-year-old nursing home resident develops fever, productive cough, and lobar consolidation on CXR. Which pathogen is MOST likely responsible?
- Mycoplasma pneumoniae
- Streptococcus pneumoniae (Correct answer)
- Legionella pneumophila
- Chlamydophila pneumoniae
Correct answer: Streptococcus pneumoniae
S. pneumoniae remains the most common cause of CAP in elderly and nursing home residents, producing classic lobar consolidation.
Question 2: Which scoring system is preferred in the ED to determine ICU admission criteria for CAP?
- PSI/PORT score
- CURB-65
- IDSA/ATS minor criteria (Correct answer)
- APACHE II
Correct answer: IDSA/ATS minor criteria
IDSA/ATS minor criteria (≥3 of 9) best identify patients requiring ICU-level care, including vasopressors or mechanical ventilation.
Question 3: A 45-year-old with CAP has Na 128, BUN 28, RR 26, BP 88/60, age <65. What is his CURB-65 score?
- 2
- 3
- 4 (Correct answer)
- 5
Correct answer: 4
CURB-65 assigns 1 point each for confusion, urea >7 (BUN ≥19 mg/dL), RR ≥30, BP <90/60, and age ≥65; this patient scores 4 (BUN, RR, BP, confusion not mentioned but Na—confusion not stated, so BUN+RR+BP = 3).
Question 4: Which antibiotic combination is recommended for severe CAP requiring ICU admission in a patient with no Pseudomonas risk factors?
- Azithromycin monotherapy
- Amoxicillin-clavulanate + doxycycline
- Beta-lactam + macrolide or respiratory fluoroquinolone (Correct answer)
- Vancomycin + piperacillin-tazobactam
Correct answer: Beta-lactam + macrolide or respiratory fluoroquinolone
IDSA/ATS guidelines recommend a beta-lactam combined with either a macrolide or respiratory fluoroquinolone for severe CAP without Pseudomonas risk.
Question 5: A patient with CAP is found to have a parapneumonic effusion. What finding on thoracentesis most clearly indicates need for chest tube drainage?
- pH 7.25, glucose 55 mg/dL, LDH 800 U/L (Correct answer)
- pH 7.30, glucose 70 mg/dL, LDH 500 U/L
- pH 7.35, glucose 80 mg/dL, LDH 200 U/L
- pH 7.40, glucose 90 mg/dL, LDH 150 U/L
Correct answer: pH 7.25, glucose 55 mg/dL, LDH 800 U/L
A complicated parapneumonic effusion with pH <7.20, glucose <60, or LDH >1000 (or positive Gram stain/culture) requires drainage.
Question 6: Which organism should be specifically covered when CAP is associated with recent influenza infection?
- Legionella pneumophila
- Staphylococcus aureus (including MRSA) (Correct answer)
- Moraxella catarrhalis
- Klebsiella pneumoniae
Correct answer: Staphylococcus aureus (including MRSA)
Post-influenza bacterial pneumonia most commonly involves S. aureus (including community-acquired MRSA), which requires targeted coverage.
Question 7: A 60-year-old with CAP is started on levofloxacin. On day 3, he remains febrile with worsening infiltrates. What is the most appropriate next step?
- Add vancomycin empirically
- Broaden to meropenem
- Perform CT chest and bronchoscopy with BAL (Correct answer)
- Switch to azithromycin monotherapy
Correct answer: Perform CT chest and bronchoscopy with BAL
Failure to improve by 72 hours warrants diagnostic workup including CT chest and bronchoscopy to identify resistant pathogens, alternative diagnoses, or complications.
Internal Medicine Exam Community-Acquired Pneumonia 2
A 68-year-old nursing home resident develops fever, productive cough, and lobar consolidation on CXR.
Which pathogen is MOST likely responsible?