Internal Medicine Exam Infectious Disease Management 5 — Questions and Answers
Question 1: A 42-year-old man with HIV (CD4 50 cells/μL, not on ART) develops progressive dyspnea. Chest CT shows bilateral ground-glass opacities. LDH is elevated. Which prophylaxis failure does this presentation most likely represent?
- Toxoplasma gondii encephalitis prophylaxis failure
- Pneumocystis jirovecii pneumonia (PCP) prophylaxis failure (Correct answer)
- Mycobacterium avium complex prophylaxis failure
- Cytomegalovirus retinitis prophylaxis failure
Correct answer: Pneumocystis jirovecii pneumonia (PCP) prophylaxis failure
Bilateral ground-glass opacities with elevated LDH in a severely immunocompromised HIV patient is classic for PCP; prophylaxis with TMP-SMX is indicated when CD4 <200 cells/μL.
Question 2: A patient is being treated for PCP with TMP-SMX. She has room air PaO2 of 62 mmHg. What adjunctive therapy should be added within 72 hours of starting antibiotics?
- Inhaled pentamidine
- Systemic corticosteroids (prednisone) (Correct answer)
- IV immunoglobulin
- Granulocyte colony-stimulating factor (G-CSF)
Correct answer: Systemic corticosteroids (prednisone)
Adjunctive corticosteroids reduce mortality in moderate-to-severe PCP (PaO2 <70 mmHg or A-a gradient >35 mmHg) by blunting the inflammatory response triggered when organisms are killed.
Question 3: A 25-year-old woman presents with high fever, headache, and a non-blanching petechial rash evolving to purpura. CSF shows gram-negative diplococci. What empiric treatment should be administered IMMEDIATELY?
- Vancomycin plus ceftriaxone
- Ceftriaxone 2 g IV immediately (Correct answer)
- Dexamethasone alone pending cultures
- Penicillin G plus metronidazole
Correct answer: Ceftriaxone 2 g IV immediately
Meningococcal meningitis/septicemia requires immediate ceftriaxone without delay; dexamethasone adjunctively reduces meningitis complications.
Question 4: A 48-year-old man develops fever and flank pain 10 days after a kidney transplant. Urinalysis shows pyuria. Urine culture grows Escherichia coli (ESBL-producing). What is the preferred treatment?
- Nitrofurantoin
- Trimethoprim-sulfamethoxazole based on susceptibilities
- Meropenem or ertapenem (Correct answer)
- Ceftriaxone
Correct answer: Meropenem or ertapenem
ESBL-producing Enterobacteriaceae are resistant to most cephalosporins and require carbapenems as the definitive treatment for serious infections in immunocompromised hosts.
Question 5: Which of the following is the MOST important measure to prevent catheter-associated urinary tract infections (CAUTIs) in hospitalized patients?
- Daily antimicrobial bladder washouts
- Routine prophylactic antibiotics in catheterized patients
- Prompt removal of urinary catheters when no longer needed (Correct answer)
- Silver-coated catheters in all ICU patients
Correct answer: Prompt removal of urinary catheters when no longer needed
The most effective CAUTI prevention strategy is daily reassessment and prompt catheter removal, as infection risk increases with each catheter-day.
Question 6: A 35-year-old traveler returns from India with watery diarrhea that progresses to rice-water stools and profound dehydration. Stool culture grows a curved gram-negative rod. What is the cornerstone of management?
- Immediate oral azithromycin
- Aggressive IV fluid resuscitation with oral rehydration salts (Correct answer)
- Ciprofloxacin monotherapy
- Loperamide plus IV vancomycin
Correct answer: Aggressive IV fluid resuscitation with oral rehydration salts
Cholera (Vibrio cholerae) management relies on rapid fluid and electrolyte replacement as the primary life-saving intervention; antibiotics (doxycycline or azithromycin) are adjunctive.
Question 7: A 60-year-old man with advanced COPD is admitted with fever, productive cough, and a new right lower lobe infiltrate 5 days into his hospital stay. He was intubated for 3 days. Which pathogen is of GREATEST concern for hospital-acquired pneumonia in this setting?
- Streptococcus pneumoniae
- Pseudomonas aeruginosa or MRSA (Correct answer)
- Legionella pneumophila
- Moraxella catarrhalis
Correct answer: Pseudomonas aeruginosa or MRSA
Hospital-acquired and ventilator-associated pneumonia are most commonly caused by drug-resistant gram-negatives (including Pseudomonas) and MRSA, requiring empiric coverage of these organisms.
Internal Medicine Exam Infectious Disease Management 5
A 42-year-old man with HIV (CD4 50 cells/μL, not on ART) develops progressive dyspnea.
Chest CT shows bilateral ground-glass opacities.
LDH is elevated.
Which prophylaxis failure does this presentation most likely represent?