Dr. Collins's point is well taken, especially given the nature of Lyme disease, which is complicated by a lack of microbiological markers of infection and cure. It was our intention to underscore the difficulty of comparing these many, often small, Lyme disease trials, which use different designs and analyses as well as variable definitions of clinical end points. These "striking contrasts" may in fact be due more to differences in study design than to antimicrobial activity. However, until a careful, double-blind, randomized trial of the various oral antimicrobial agents is done, it is impossible to determine the optimal agent for the treatment of erythema migrans.

Careful review of our records shows that the patient described by Dr. Patmas may be a 71-year-old white man who had relapse on study day 187 after having had a partial response on day 20. However, this patient received azithromycin. Without further information on the enrollment site and on whether the patient appeared for his follow-up visits on days 30, 90, and 180, it is impossible to definitively resolve Dr. Patmas's query. Unfortunately, one of the limitations of our study was the duration of follow-up.