Woznicová, Vladana, et al. “Clarithromycin Treatment Failure Due to Macrolide Resistance in Treponema Pallidum in a Patient With Primary Syphilis”. Acta Dermato-Venereologica, vol. 90, no. 2, Jan. 2010, pp. 206-7, doi:10.2340/00015555-0774.