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Difficulty: HardInfectious Diseases

Match each patient's clinical presentation with the most appropriate targeted antimicrobial therapy.

  • A 28-year-old pregnant woman (10 weeks gestation) who developed a painless, 8-cm erythematous rash with central clearing on her right thigh, one week after a hiking trip in Connecticut.Oral amoxicillin
  • A 6-year-old boy who presents with a 3-day history of high fever, severe headache, and a petechial rash that began on his wrists and ankles before spreading centrally, following a camping trip in North Carolina.Oral doxycycline
  • A 45-year-old man with a history of splenectomy who presents with fever, jaundice, dark urine, and a peripheral blood smear demonstrating intraerythrocytic pleomorphic ring forms and tetrads.Oral atovaquone and azithromycin
  • A 55-year-old man who presents with fever, a painful ulcer on his right index finger, and tender right axillary lymphadenopathy, 5 days after skinning wild rabbits on a hunting trip.Intramuscular streptomycin

Answer

The correct pairings are: 1) Pregnant woman with Lyme disease matches with Oral amoxicillin; 2) 6-year-old boy with RMSF matches with Oral doxycycline; 3) Asplenic man with Babesiosis matches with Oral atovaquone and azithromycin; 4) Man with Tularemia matches with Intramuscular streptomycin.
Each clinical vignette provides classic epidemiological and clinical clues for a specific zoonotic or tick-borne infection, testing the ability to select the gold-standard therapy while navigating crucial exceptions, such as pregnancy and pediatric age restrictions.

Step-by-Step Solution

1
Analyze the first clinical scenario involving the pregnant woman with a targetoid rash.
The diagnosis is early localized Lyme disease. The patient is in her first trimester of pregnancy, requiring a teratogen-sparing regimen.
To determine the appropriate antibiotic that is safe for fetal development, leading to the selection of amoxicillin over doxycycline.
2
Analyze the second clinical scenario involving the 6-year-old boy with a centripetally spreading petechial rash.
The diagnosis is Rocky Mountain Spotted Fever. Despite his young age, doxycycline is the standard of care.
To apply the specific clinical exception where doxycycline is used in children under 8 years old because the disease carries a high mortality rate if untreated.
3
Analyze the third clinical scenario involving the asplenic man with hemolytic anemia and tetrads on blood smear.
The diagnosis is babesiosis. First-line therapy consists of anti-parasitic agents, specifically atovaquone combined with azithromycin.
To identify the specific anti-protozoal regimen required for this tick-borne illness.
4
Analyze the fourth clinical scenario involving the man with a finger ulcer and regional lymphadenopathy after rabbit exposure.
The diagnosis is ulceroglandular tularemia. Aminoglycosides are the treatment of choice.
To match the zoonotic pathogen (Francisella tularensis) to its highly effective specific pharmacotherapy.

Key Concept

Selection of targeted antimicrobial therapy for zoonotic and tick-borne infections often requires deviating from general rules based on specific patient demographics (e.g., pregnancy, young age) and precise pathogen identification.

Alternative Method

For severe, life-threatening babesiosis (e.g., parasitemia greater than 10%, severe hemolysis, or pulmonary edema), an alternative regimen of intravenous clindamycin and oral quinine is utilized, and patients may additionally require red blood cell exchange transfusion.
Estimated Time:2m 0s
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Infectious Diseases

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