Clinical Decisionmaking

Antibiotic treatment of Lyme disease depends on clinical signs and symptoms

Antibiotic treatment of Lyme disease (LD), which is transmitted by a bite from a deer tick, depends primarily on the patient's clinical signs and symptoms, according to a study supported by the Agency for Health Care Policy and Research (HS07813). Patients whose only symptom is a bulls-eye rash surrounding the tick bite (erythema migrans, EM) typically receive a 3-week course of doxycycline or amoxicillin. At the other extreme, 25 to 40 percent of patients with joint, neurologic, cardiac, or multiple extracutaneous symptoms or with systemic Lyme disease receive 2 to 3 weeks of intravenous ceftriaxone.The study was led by G. Thomas Strickland, M.D., Ph.D., of the University of Maryland School of Medicine.

Dr. Strickland and his colleagues studied Maryland State reporting forms completed by physicians to identify the antibiotics used to treat 1,601 patients (aged 1 to 92 years) diagnosed with LD by the reporting physician. They classified the patients into three groups: EM alone, EM and extracutaneous symptoms, and late manifestations of Lyme disease. Eighty-eight percent of the patients were treated initially with doxycycline, amoxicillin, or ceftriaxone; another 4 percent were treated with tetracycline. Eight-eight percent of the patients received one antibiotic, and about 12 percent were treated with two or more courses of antibiotics within 2 months following diagnosis.

Patients with EM alone were more apt to receive one course of antibiotic than those with extracutaneous symptoms, with or without EM. The average duration of the second course of oral antibiotic ranged from 21 days for those only having EM to 28 days for those having chronic manifestations. Intravenous ceftriaxone, which is significantly more expensive and potentially more toxic than oral doxycycline and amoxicillin, was used primarily for patients with joint, neurologic, and multiple extracutaneous manifestations (mean of 21 days) and for those with cardiac manifestations (mean of 15 days).

Details are in "Antibiotic therapy of Lyme disease in a population-based cohort," by Cesar A. Pena, D.V.M., M.S., Anita A. Mathews, M.S., Nauman H. Siddiqi, M.S., and Dr. Strickland, in the September 1999 Clinical Infectious Diseases 29, pp. 694-695.

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