Three cases of cutaneous sarcoidosis: search for bacterial agent by the 16S RNA gene analysis and treatment with antibiotics

BACKGROUND: The aetiology of sarcoidosis remains controversial. An infectious origin is often discussed, but only anti-inflammatory or immunosuppressive treatment is recommended. OBJECTIVES: To investigate the hypothesis of bacterial origin by treating cutaneous sarcoidosis with antibiotics. METHODS: Patients with chronic cutaneous sarcoidosis, unresponsive to the usual treatment and not requiring systemic corticotherapy, were given combined antibiotherapy for 6 months. Search for bacterial DNA by amplification and sequencing of the 16S ribosomal RNA gene in skin biopsies of lesions before and after antibiotherapy was done. RESULTS: Three patients received a combined treatment with clarithromycin 1 g/day and ciprofloxacin 1 g/day. No clinical changes occurred in 2 cases and transient worsening in 1. Amplification for bacterial DNA was positive in all skin biopsies. The sequencing of this DNA could not identify a unique bacterial species. CONCLUSION: No evident bacterial origin could be demonstrated; however, this approach should be extended to more patients.