Internal Medicine Exam Community-Acquired Pneumonia 4 — Questions and Answers
Question 1: A 72-year-old with COPD develops CAP. Which outpatient antibiotic regimen is recommended by IDSA guidelines?
- Amoxicillin 500 mg TID
- Azithromycin monotherapy
- Respiratory fluoroquinolone OR beta-lactam + macrolide (Correct answer)
- Trimethoprim-sulfamethoxazole
Correct answer: Respiratory fluoroquinolone OR beta-lactam + macrolide
Patients with comorbidities (COPD, DM, heart failure, etc.) should receive a respiratory fluoroquinolone or beta-lactam/macrolide combination to cover resistant organisms.
Question 2: Which criterion defines 'severe CAP' requiring ICU admission per IDSA/ATS major criteria?
- CURB-65 ≥3
- Need for mechanical ventilation OR septic shock requiring vasopressors (Correct answer)
- Oxygen saturation <94% on room air
- Bilateral infiltrates on CXR
Correct answer: Need for mechanical ventilation OR septic shock requiring vasopressors
IDSA/ATS major criteria for severe CAP are: need for invasive mechanical ventilation OR septic shock requiring vasopressors.
Question 3: Procalcitonin (PCT) is most useful in CAP management for which purpose?
- Identifying the causative organism
- Guiding antibiotic duration and de-escalation (Correct answer)
- Predicting 30-day mortality
- Differentiating bacterial from fungal pneumonia
Correct answer: Guiding antibiotic duration and de-escalation
Serial PCT measurements guide antibiotic duration — declining PCT levels support stopping antibiotics, reducing unnecessary therapy.
Question 4: A healthy 30-year-old college student develops low-grade fever, dry cough, and diffuse bilateral interstitial infiltrates over 2 weeks. Which pathogen is most likely?
- Streptococcus pneumoniae
- Klebsiella pneumoniae
- Mycoplasma pneumoniae (Correct answer)
- Staphylococcus aureus
Correct answer: Mycoplasma pneumoniae
M. pneumoniae causes 'walking pneumonia' in young adults — insidious onset, dry cough, mild symptoms, and interstitial infiltrates out of proportion to clinical severity.
Question 5: Which vaccine has the greatest impact on reducing CAP incidence in adults over 65?
- Influenza vaccine alone
- PCV15 or PCV20 (pneumococcal conjugate vaccine) (Correct answer)
- PPSV23 alone
- Tdap booster
Correct answer: PCV15 or PCV20 (pneumococcal conjugate vaccine)
Higher-valency pneumococcal conjugate vaccines (PCV15, PCV20) are now preferred over PPSV23 alone for adults ≥65, providing superior immunogenicity and protection.
Question 6: A 58-year-old with CAP is switched from IV to oral antibiotics. Which criteria must be met before this transition?
- Afebrile for 24 hours only
- Clinical stability: improving symptoms, HR <100, RR <24, O2 sat ≥90%, tolerating oral intake (Correct answer)
- Normal WBC count
- Repeat CXR showing improvement
Correct answer: Clinical stability: improving symptoms, HR <100, RR <24, O2 sat ≥90%, tolerating oral intake
IV-to-oral switch is guided by clinical stability criteria — hemodynamic improvement, reduced fever, normal mentation, and ability to take oral medications.
Question 7: Which organism causing CAP is classically associated with 'currant jelly' sputum and upper lobe cavitation in alcoholic patients?
- Streptococcus pneumoniae
- Pseudomonas aeruginosa
- Klebsiella pneumoniae (Correct answer)
- Anaerobes
Correct answer: Klebsiella pneumoniae
Klebsiella pneumoniae causes a severe necrotizing pneumonia in alcoholics with characteristic bloody mucoid ('currant jelly') sputum and upper lobe cavitation.
Internal Medicine Exam Community-Acquired Pneumonia 4
A 72-year-old with COPD develops CAP.
Which outpatient antibiotic regimen is recommended by IDSA guidelines?