Objective: To determine if clarithromycin monotherapy is safe and effective in treating cutaneous disease (especially disseminated disease) due to Mycobacterium chelonae (formerly M. chelonae subspecies chelonae).
Design: An open, noncomparative trial of clarithromycin as single-drug therapy.
Setting: Nationwide referrals.
Patients: Culture-positive patients whose M. chelonae came from a cutaneous source and whose isolate was submitted to a single referral laboratory for susceptibility testing.
Intervention: Clarithromycin, 500 mg twice a day by mouth for 6 months. No attempt was made to alter use of immunosuppressive drugs.
Main outcome measures: Acid-fast bacilli smears and cultures of skin lesions during and after treatment, with monitoring of clinical response, side effects, and development of new lesions.
Results: Fourteen patients (10 with disseminated disease) were enrolled in the study and completed at least 3 months of therapy. Underlying diseases included rheumatoid arthritis, other autoimmune disorders, and organ transplantation. All were taking corticosteroids (93%) or cyclophosphamide (7%). All patients had an excellent response to therapy, with only mild side effects from the drug. Two patients died of other diseases after improving clinically but while still taking medication. One noncompliant patient who prematurely discontinued therapy after 3.5 months relapsed 1 month later with an isolate resistant to clarithromycin. The remaining 11 patients have all completed therapy given for a mean of 6.8 months (range, 4.5 to 9 months). Therapy has been discontinued for 9 of the 11 patients for at least 6 months (mean, 7.1 months; range, 6 to 12 months), with no evidence of relapse. No remaining patient had positive acid-fast bacilli smears or cultures of skin lesions after 1 month of therapy.
Conclusions: Clarithromycin may be the drug of choice for cutaneous (disseminated) disease due to M. chelonae, although more patients with long-term clinical follow-up need to be studied.