We tested in vitro susceptibility of 5 strains of Borrelia burgdorferi sensu lato, isolated from patients in the Czech Republic, to penicillin G, ceftriaxone, cefotaxime, doxycycline and amoxycillin combined with clavulanic acid by broth macrodilution method on BSK medium. Results confirmed high efficacy of the tested drugs, particularly on B. afzelii and B. burgdorferi sensu stricto. A strain of B. garinii , isolated from cerebrospinal fluid, required a longer period of antibiotic activity before inhibitory effects were achieved. Penicillin G was effective only in higher concentrations, attainable by i.v. application. Ceftriaxone had the strongest borreliacidal activity.

        Key words: Borrelia burgdorferi sensu lato, Borrelia burgdorferi sensu stricto, Borrelia afzelii, Borrelia garinii, antibiotic susceptibility, ceftriaxone, cefotaxime, amoxycillin combined with clavulanic acid, doxycycline