ROXITHROMYCIN IN THE TREATMENT OF LYME-DISEASE - UPDATE AND PERSPECTIVES

Spirochaetal infections have been successfully treated with penicillin ; more recently, erythromycin has been used in cases with known penici llin allergy. The discovery of the spirochaete Borrelia burgdorferi an d the elaboration of a new generation of macrolides with properties th at differ from older macrolides have led to new ways of treating spiro chaetal disease with these compounds. This paper presents data on the in vitro and in vivo efficacy of a combination of roxithromycin and co -trimoxazole against B. burgdorferi. In vitro (checkerboard technique; B. burgdorferi strain B31; modified BSK II medium) it was found that while roxithromycin showed excellent efficacy against B. burgdorferi ( MIC 0.031 mg/l), co-trimoxazole had no effect. However, the combinatio n of both chemotherapeutics led to a minor synergistic effect, decreas ing the MIC for roxithromycin by one dilution step at concentrations o f co-trimoxazole from 256 to 8 mg/l. In addition, a clearly reduced gr owth of microorganisms was seen at concentrations of roxithromycin as low as 0.015 mg/l in combination with 256 to 4 mg/l co-trimoxazole, wh en compared to the positive controls. Most interestingly, however, the motility of B. burgdorferi was markedly reduced even when the two dru gs were combined at very low concentrations. In an in vivo, non-random ised, open, prospective pilot study it was found that of 17 patients w ith confirmed late Lyme borreliosis (stage II/III), treated with combi ned roxithromycin (300 mg b.i.d.) and co-trimoxazole for 5 weeks, 13 ( 76%) recovered completely by the end of treatment, and four continued to have symptoms on follow-up at 6 and 12 months. This success rate is similar to that seen with i.v. penicillin and ceftriaxone. It appears that the reduced motility of B. burgdorferi makes the pathogen more a ccessible to the immune system.