COMPARATIVE IN-VITRO ACTIVITIES OF CLARITHROMYCIN, AZITHROMYCIN, AND ERYTHROMYCIN AGAINST BORRELIA-BURGDORFERI

The in vitro activities of the macrolide antibiotics clarithromycin, 14-hydroxy-clarithromycin, azithromycin, and erythromycin against 19 isolates of Borrelia burgdorferi were investigated. MICs ranged from 0.003 to 0.03 mug of clarithromycin per ml, 0.007 to 0.03 mug of 14-hydroxyclarithromycin per ml, 0.003 to 0.03 mug of azithromycin per ml, and 0.007 to 0.06 mug of erythromycin per ml. Time-kill studies using the B31 strain of B. burgdorferi demonstrated a greater-than-or-equal-to 3-log10-unit killing after 72 h with each of the macrolide antibiotics tested in concentrations representing twice the respective MICs.