Internal Medicine Exam Infectious Disease Management 2 — Questions and Answers
Question 1: A 45-year-old HIV-positive patient with CD4 count of 80 cells/μL presents with headache and fever. CSF India ink stain is positive. What is the initial treatment of choice?
- Fluconazole 400 mg daily
- Amphotericin B deoxycholate plus flucytosine (Correct answer)
- Voriconazole IV
- Caspofungin IV
Correct answer: Amphotericin B deoxycholate plus flucytosine
Cryptococcal meningitis induction therapy is liposomal amphotericin B (or deoxycholate) plus flucytosine for 2 weeks, followed by fluconazole consolidation.
Question 2: Which antibiotic class is the treatment of choice for community-acquired pneumonia caused by atypical organisms such as Mycoplasma pneumoniae in an otherwise healthy outpatient adult?
- Beta-lactams
- Macrolides (Correct answer)
- Carbapenems
- Aminoglycosides
Correct answer: Macrolides
Macrolides (e.g., azithromycin) are first-line for atypical CAP in healthy outpatients because they cover Mycoplasma, Chlamydophila, and Legionella.
Question 3: A 30-year-old woman returning from sub-Saharan Africa presents with cyclic fevers every 48 hours, anemia, and splenomegaly. Blood smear shows ring forms with banana-shaped gametocytes. What is the appropriate treatment?
- Chloroquine
- Artemether-lumefantrine (Correct answer)
- Doxycycline monotherapy
- Metronidazole
Correct answer: Artemether-lumefantrine
Banana-shaped gametocytes indicate Plasmodium falciparum; artemisinin-based combination therapy (e.g., artemether-lumefantrine) is first-line for uncomplicated falciparum malaria.
Question 4: A patient with penicillin allergy (anaphylaxis) requires treatment for neurosyphilis. What is the recommended management?
- Doxycycline 100 mg BID for 28 days
- Ceftriaxone 2 g IV daily for 10–14 days
- Penicillin desensitization followed by IV penicillin G (Correct answer)
- Azithromycin 2 g single dose
Correct answer: Penicillin desensitization followed by IV penicillin G
Penicillin G remains the only proven therapy for neurosyphilis; patients with penicillin allergy should undergo desensitization and then receive IV penicillin G.
Question 5: A 65-year-old diabetic man develops a rapidly spreading, painful necrotizing infection of the perineum with crepitus on exam. What is the MOST critical initial intervention after resuscitation?
- Broad-spectrum antibiotics alone
- Hyperbaric oxygen therapy
- Emergency surgical debridement (Correct answer)
- CT-guided drainage
Correct answer: Emergency surgical debridement
Fournier's gangrene (necrotizing fasciitis) requires urgent surgical debridement as the cornerstone of treatment; antibiotics are adjunctive but cannot replace surgery.
Question 6: Which mechanism best explains vancomycin resistance in Enterococcus faecium (VanA phenotype)?
- Altered penicillin-binding proteins
- Enzymatic beta-lactamase production
- Substitution of D-Ala-D-Lac for D-Ala-D-Ala in peptidoglycan precursors (Correct answer)
- Efflux pump overexpression
Correct answer: Substitution of D-Ala-D-Lac for D-Ala-D-Ala in peptidoglycan precursors
VanA resistance results from replacing the terminal D-Ala-D-Ala with D-Ala-D-Lac, dramatically reducing vancomycin binding affinity.
Question 7: A 28-year-old man presents with urethral discharge. Gram stain shows intracellular gram-negative diplococci. Which treatment regimen addresses both gonorrhea and likely co-infection?
- Penicillin G IM single dose
- Ceftriaxone 500 mg IM plus doxycycline 100 mg BID × 7 days (Correct answer)
- Ciprofloxacin 500 mg single oral dose
- Metronidazole plus azithromycin
Correct answer: Ceftriaxone 500 mg IM plus doxycycline 100 mg BID × 7 days
CDC guidelines recommend ceftriaxone for gonorrhea plus doxycycline (or azithromycin) to treat concurrent Chlamydia trachomatis co-infection.
Internal Medicine Exam Infectious Disease Management 2
A 45-year-old HIV-positive patient with CD4 count of 80 cells/μL presents with headache and fever.
CSF India ink stain is positive.
What is the initial treatment of choice?