Four swab specimens were obtained from the wound, and quantitative real-time PCR assay targeting the IS2404 putative transposase gene and the mycolactone
polyketide synthase gene confirmed the presence of M.
Morel et al., "Sec61 blockade by mycolactone
inhibits antigen cross-presentation independently of endosome-to-cytosol export," Proceedings of the National Academy of Sciences of the United States of America, vol.
, a secreted exotoxin, is the only virulence factor identified to date for Mycobacterium ulcerans (MU) .
70% protein coding genes; Generation time: ~ 20 hours Toxin Mycolactone
(encoded by plasmid) in vitro cultivation Yes Clinical presentation Skin papules, plaques, nodules, ulcers, edemas; especially extremities; bone lesions in ~ 10% (Africa) Both diseases develop early skin signs that patients often overlook Favors cooler body parts Yes Disease spectrum Papule, nodule or plaque, then self-heals or enlarges, often ulcerating HIV a risk factor Yes; more severe disease observed Tuberculosis co-infection Both organisms, same skin lesion: 3 />5000 Pulmonary TB after BU Rx: l/>5000 Molecular Investigations on-going epidemiology Transmission Non-contagious Traumatic implantation; aquatic insect bites?
This organism is apparently adapted now to a dark and aerobic atmosphere, where its reduced antigenicity, slow growth, and mycolactone
production provided advantages for its survival.
The scientists eventually purified a yellow waxy substance, which they called mycolactone
. In test-tube experiments, it prompts skin cells to become rounder and eventually die.
ulcerans is driven by production of mycolactone
, a polyketide-derived macrolide that triggers apoptotic cell death (1).
These presentations have been observed to be the cytotoxic effect of the toxin mycolactone
produced by the growing MU in the host [6,7].
Much of the pathology of this debilitating disease is caused by mycolactone
, a macrolide toxin (2) unique for members of the species M.
ulceraos histopathology is the absence of granulomas and presence of extensive necrosis caused by the organism's secretion of mycolactone
toxin, which suppresses the host's immune response (7).
ulcerans produces a potent toxin known as mycolactone
(2), which lyses dermal cells, leading to the development of continuously expanding ulcers with undermined edges.