A 10-year-old girl presents to your urgent care outside of Philadelphia with a mild fever, fatigue, and a rash on her lower leg. On examination, you note that the rash has a “bull’s-eye” appearance and is 12 cm in diameter; she says it is not painful and does not itch. When asked, the patient does not recall a tick bite. Her mother reports that the girl has been attending a local summer day camp where she frequently participates in outdoor activities, including hikes in a wooded area. You confirm that the patient has no known drug allergies. What is the best next step in management of this patient?
a. Do nothing, but advise the patient’s mother to apply cortisone cream to the rash and watch the child for worsening signs or symptoms.
b. Order confirmatory testing and wait for the results to guide antibiotic selection
c. Prescribe doxycycline
d. Prescribe azithromycin
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Answer: C. While the patient does not recall a tick bite, she has been engaged in outdoor activities in Pennsylvania, where Lyme disease is endemic. Her rash has the hallmark appearance of erythema migrans, which is characteristic of Lyme disease. Erythema migrans can be treated based on clinical findings alone; confirmatory testing should not delay initiation of treatment. Doxycycline is the antibiotic of choice to treat early localized Lyme disease in the absence of any known contraindications. Recent studies have largely disproved an elevated risk for adverse effects of doxycycline in children (in particular, teeth staining) with short courses of treatment.