Isolation of Borrelia burgdorferi sensu lato from blood of children with solitary erythema migrans

Objectives. To establish the frequency of isolation of Borrelia burgdorferi sensu late from blood of children with solitary erythema migrans (EM) in E urope, to determine the strains of the isolated borreliae and to compare th e clinical course and the outcome of the disease according to positive and negative blood culture result. Methods. In the prospective study we included 134 consecutive patients youn ger than 15 years with solitary EM, referred to our institution in 1996 and 1997. One milliliter of blood was withdrawn before treatment and cultured in modified Kelly-Pettenkofer medium. Isolated borreliae were typed accordi ng to LRFP analysis. Patients were treated with either penicillin V or cefu roxime axetil for 14 days. The posttreatment course was surveyed by follow- up visits during 1 year. Results. B. burgdorferi sensu late was isolated in 12 of 134 (9%) patients. Eleven blood isolates were typed: 10 were found to be B. afzelii and 1 was Borrelia garinii. Comparison of blood culture-positive and -negative patie nts revealed no differences in pretreatment characteristics or in posttreat ment clinical course. However, worsening of local and/or systemic signs and symptoms at the beginning of antibiotic therapy (Jarish-Herxheimer's react ion) was identified more often in the blood culture-positive than in the bl ood culture-negative group (5 of 12 vs. 17 of 122, respectively; P = 0.0274 ). Conclusions. The isolation rate of B. burgdorferi sensu late from the blood of children with solitary EM was 9%. The majority of the isolates were B. afzelii. Blood culture-positive patients treated with oral antibiotics were not at greater risk for unfavorable course of the disease than patients wi th negative blood culture result.