72 patients with Erythema chronicum migrans were treated with phenoxymethyl penicillin, 1,5 mill. IU p.o. three times a day for 14 days. Two children got the same therapy, but in a dosage of 400,000 IU three times a day for 10 days. In three of 15 skin samples, taken from the periphery of ECM lesions, spirochetal organisms were isolated. Of the 72 patients 16 had raised IgG (greater than or equal to 128) and 9 had raised IgM (greater than or equal to 64) titers to Borrelia burgdorferi. Under treatment with phenoxymethyl penicillin (penicillin V) all ECM lesions resolved within 6 to 10 days. After an observation period of 9 to 14 months no major or minor late manifestations of
Lyme disease have developed in any of the 72 patients.