Internal Medicine Exam Community-Acquired Pneumonia 5 — Questions and Answers
Question 1: A 66-year-old on chronic corticosteroids develops CAP with bilateral ground-glass opacities and a CD4 count of 180. LDH is markedly elevated. What is the most likely diagnosis?
- Bacterial lobar pneumonia
- Pneumocystis jirovecii pneumonia (PCP) (Correct answer)
- Legionella pneumonia
- Viral influenza pneumonia
Correct answer: Pneumocystis jirovecii pneumonia (PCP)
PCP should be suspected in immunocompromised patients (corticosteroids, low CD4) with bilateral ground-glass infiltrates and elevated LDH.
Question 2: Which finding on urinalysis would suggest Legionella as the etiology of CAP?
- Nitrite positive dipstick
- Positive Legionella urinary antigen (Correct answer)
- Eosinophiluria
- Hematuria with casts
Correct answer: Positive Legionella urinary antigen
The Legionella urinary antigen test is performed on urine and is the rapid diagnostic of choice, detecting serogroup 1 antigen.
Question 3: A 55-year-old presents with CAP and a PSI score placing him in Risk Class IV. What is the recommended site of care?
- Outpatient
- Observation unit only
- Inpatient hospitalization (Correct answer)
- ICU admission
Correct answer: Inpatient hospitalization
PSI Risk Class IV (score 91–130) carries significant mortality risk (8.2%) and warrants inpatient hospitalization.
Question 4: Which empiric antibiotic is recommended for CAP in a hospitalized non-ICU patient with a penicillin allergy (non-anaphylactic)?
- Azithromycin monotherapy
- Respiratory fluoroquinolone (levofloxacin or moxifloxacin) (Correct answer)
- Vancomycin + azithromycin
- Clindamycin + ceftriaxone
Correct answer: Respiratory fluoroquinolone (levofloxacin or moxifloxacin)
A respiratory fluoroquinolone alone provides adequate monotherapy for non-ICU hospitalized CAP and avoids beta-lactam use in penicillin-allergic patients.
Question 5: What is the most common cause of CAP-associated empyema requiring surgical drainage?
- Streptococcus pneumoniae (Correct answer)
- Mycoplasma pneumoniae
- Legionella pneumophila
- Chlamydophila pneumoniae
Correct answer: Streptococcus pneumoniae
S. pneumoniae is the leading cause of empyema complicating CAP; empyemas that fail chest tube drainage may require VATS or open decortication.
Question 6: A 40-year-old bird handler develops CAP with headache, dry cough, and splenomegaly. Which pathogen is most likely?
- Coxiella burnetii
- Chlamydophila psittaci (Correct answer)
- Histoplasma capsulatum
- Francisella tularensis
Correct answer: Chlamydophila psittaci
Psittacosis (C. psittaci) is a zoonotic atypical pneumonia associated with bird exposure, characterized by headache, dry cough, and splenomegaly.
Question 7: What is the recommended follow-up chest X-ray interval after hospitalization for CAP in a patient over 50 who smokes?
- 1 week post-discharge
- 4–6 weeks post-discharge (Correct answer)
- 3 months post-discharge
- No follow-up needed if improved
Correct answer: 4–6 weeks post-discharge
Follow-up CXR at 4–6 weeks is recommended in older smokers to confirm radiographic resolution and exclude underlying malignancy masquerading as CAP.
Internal Medicine Exam Community-Acquired Pneumonia 5
A 66-year-old on chronic corticosteroids develops CAP with bilateral ground-glass opacities and a CD4 count of 180.
LDH is markedly elevated.
What is the most likely diagnosis?