ITE Infectious Disease Management 4 — Questions and Answers
Question 1: A 40-year-old man returns from a trip to sub-Saharan Africa with fever, chills, and headache starting 10 days after return. Peripheral blood smear shows ring forms in >5% of RBCs with multiple rings per cell. What is the treatment?
- Chloroquine 600mg base then 300mg at 6h, 24h, 48h
- Atovaquone-proguanil plus doxycycline
- IV artesunate (Correct answer)
- Quinine plus doxycycline
Correct answer: IV artesunate
Severe falciparum malaria (parasitemia >5%) requires IV artesunate, which is now available in the US and superior to IV quinine for severe disease.
Question 2: A 68-year-old man on hemodialysis develops bacteremia with MSSA. TEE shows no vegetation. What is the recommended duration of antibiotic therapy for uncomplicated MSSA bacteremia?
- 7 days
- 14 days (Correct answer)
- 28 days
- 42 days
Correct answer: 14 days
Uncomplicated S. aureus bacteremia (no endocarditis, no metastatic focus, clinical improvement by 72h) requires 14 days of IV anti-staphylococcal therapy.
Question 3: A 35-year-old woman is found to have latent tuberculosis infection (LTBI) with a positive IGRA. She has no active TB symptoms. She is not pregnant and has no liver disease. What is the preferred LTBI treatment regimen?
- Isoniazid 300mg daily for 9 months
- Isoniazid 300mg daily for 6 months
- Rifampin 600mg daily for 4 months
- Isoniazid plus rifapentine weekly for 12 weeks (3HP) (Correct answer)
Correct answer: Isoniazid plus rifapentine weekly for 12 weeks (3HP)
The 3HP regimen (weekly isoniazid plus rifapentine for 12 weeks) is preferred for LTBI due to superior completion rates compared to 9-month isoniazid monotherapy.
Question 4: A 45-year-old male traveler develops profuse watery diarrhea, nausea, and vomiting 2 days after returning from India. Stool cultures show Vibrio cholerae. What is the primary treatment priority?
- Ciprofloxacin 1g single dose
- Doxycycline 300mg single dose
- IV fluid resuscitation with Ringer's lactate (Correct answer)
- Azithromycin 1g single dose
Correct answer: IV fluid resuscitation with Ringer's lactate
Aggressive fluid and electrolyte replacement is the cornerstone of cholera treatment, as severe dehydration causes most deaths; antibiotics are adjunctive.
Question 5: A 30-year-old woman with recurrent UTIs asks about post-coital prophylaxis. She has 3 UTIs per year, all temporally related to sexual intercourse. Which regimen is appropriate?
- Daily TMP-SMX DS continuously for 6 months
- Single-dose TMP-SMX SS taken within 2 hours of intercourse (Correct answer)
- Nitrofurantoin 100mg nightly for 12 months
- Cranberry extract 500mg daily
Correct answer: Single-dose TMP-SMX SS taken within 2 hours of intercourse
Post-coital single-dose TMP-SMX or nitrofurantoin is effective prophylaxis for women whose UTIs are clearly linked to sexual activity.
Question 6: A 55-year-old man with diabetes presents with right lower extremity cellulitis and fever. He was treated with cephalexin for 5 days without improvement. What additional coverage should be empirically added?
- Clindamycin alone
- TMP-SMX or doxycycline (MRSA coverage) (Correct answer)
- Piperacillin-tazobactam
- Metronidazole
Correct answer: TMP-SMX or doxycycline (MRSA coverage)
Failure to improve on beta-lactam therapy for cellulitis should prompt consideration of MRSA, and empiric MRSA coverage with TMP-SMX or doxycycline should be added.
Question 7: A 62-year-old patient with cirrhosis develops spontaneous bacterial peritonitis (SBP). Ascitic fluid PMN count is 350 cells/µL. What is the empiric antibiotic of choice?
- Amoxicillin-clavulanate PO
- Cefotaxime 2g IV q8h (Correct answer)
- Metronidazole plus ciprofloxacin
- Vancomycin plus piperacillin-tazobactam
Correct answer: Cefotaxime 2g IV q8h
Cefotaxime (or ceftriaxone) is the empiric antibiotic of choice for SBP, providing excellent gram-negative coverage without nephrotoxicity in an already vulnerable population.
ITE Infectious Disease Management 4
A 40-year-old man returns from a trip to sub-Saharan Africa with fever, chills, and headache starting 10 days after return.
Peripheral blood smear shows ring forms in >5% of RBCs with multiple rings per cell.
What is the treatment?