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 μg of clarithromycin per ml, 0.007 to 0.03 μg of 14-hydroxyclarithromycin per ml, 0.003 to 0.03 μg of azithromycin per ml, and 0.007 to 0.06 μg of erythromycin per ml. Time-kill studies using the B31 strain of B. burgdorferi demonstrated a ≥3-log10-unit killing after 72 h with each of the macrolide antibiotics tested in concentrations representing twice the respective MICs.
Dever, L. L., Jorgensen, J. H., & Barbour, A. G. (1993). Comparative in vitro activities of clarithromycin, azithromycin, and erythromycin against Borrelia burgdorferi. Antimicrobial Agents and Chemotherapy. https://doi.org/10.1128/AAC.37.8.1704