Ulcerans

Ulcerans is most commonly encountered as the specific epithet in the bacterium Mycobacterium ulcerans, the causative agent of Buruli ulcer. It is a slow‑growing member of the genus Mycobacterium, within the family Mycobacteriaceae, and is related to other environmental mycobacteria. The organism is notable for producing the lipid-like toxin mycolactone, which contributes to tissue necrosis and the distinctive necrotizing ulcers seen in infection.

Buruli ulcer, the disease caused by M. ulcerans, typically begins as a painless nodule, swelling, or plaque that can expand into a large ulcer with undermined edges. Lesions most often affect the limbs and can lead to functional impairment if untreated. The pathogenesis is strongly linked to mycolactone production, which has cytotoxic and immunomodulatory effects that damage skin and subcutaneous tissues. The exact mode of transmission remains incompletely understood, but the bacterium is associated with aquatic environments and environmental reservoirs.

Diagnosis of M. ulcerans infection relies on laboratory testing, with polymerase chain reaction (PCR) targeting IS2404 providing a sensitive and specific method for confirming Buruli ulcer. Culture and histopathology can support diagnosis but may be less practical in routine settings due to slow growth and sample requirements.

Treatment uses a combination antibiotic regimen, typically rifampicin with another agent such as streptomycin or clarithromycin, for about eight weeks. Early antibiotic therapy can reduce the need for surgical intervention, though debridement or excision may be necessary for large or necrotic lesions. Prevention focuses on early detection and prompt treatment; no widely used vaccine exists, and the role of prior BCG vaccination in protection against M. ulcerans infection is not definitive.