Genetic variants in human BCL2L11 (BIM) are associated with ulcerative forms of Buruli ulcer

Mycobacterial skin infection

PURPOSE OF REVIEW

The aim of this article is to review the most recent evidences concerning mycobacterial skin infections, limiting the period of literature research to 2020--2021.

RECENT FINDINGS

Mycobacterial skin infections include a heterogeneous group of cutaneous diseases.Cutaneous tuberculosis is usually the result of hematogenous dissemination or spread from underlying foci and it must be distinguished from tuberculids, resulting from the immunological reaction to Mycobacterium tuberculosis antigens. Leprosy prevalence was drastically reduced after introduction of multidrug therapy in the 1980 s, but cases are still reported due to underdiagnosis, and animal and environmental reservoirs. Recent advances concentrate in the diagnostic field. Specific guidelines for the treatment of nontuberculous mycobacteria skin infections are missing and surgical procedures may be required. Prognosis is better as compared to nontuberculous mycobacteria lung disease. Rapid laboratory-confirmed diagnosis of Buruli ulcer may be achieved by the IS2404 PCR. Among new drugs, telacebec is promising in terms of potency, shorter duration and tolerability in animal studies. A clinical trial in humans is planned.

SUMMARY

Mycobacterial cutaneous lesions are nonpathognomonic and clinical suspicion must be confirmed by culture or molecular detection. Long-course multidrug treatment is required based on susceptibility tests. Surgical intervention may also be required. Rehabilitation and psychosocial support reduce long-term physical and mental consequences mostly in Buruli ulcer and leprosy.

Molecular and epidemiological characterization of recurrent Mycobacterium ulcerans infections in Benin

BACKGROUND

Buruli ulcer is a neglected tropical disease caused by Mycobacterium ulcerans, an environmental mycobacterium. Although transmission of M. ulcerans remains poorly understood, the main identified risk factor for acquiring Buruli ulcer is living in proximity of potentially contaminated water sources. Knowledge about the clinical features of Buruli ulcer and its physiopathology is increasing, but little is known about recurrence due to reinfection.

METHODOLOGY/PRINCIPAL FINDINGS

We describe two patients with Buruli ulcer recurrence due to reinfection with M. ulcerans, as demonstrated by comparisons of DNA from the strains isolated at the time of the first diagnosis and at recurrence. Based on the spatial distribution of M. ulcerans genotypes in this region and a detailed study of the behavior of these two patients with respect to sources of water as well as water bodies and streams, we formulated hypotheses concerning the sites at which they may have been contaminated.

CONCLUSIONS/SIGNIFICANCE

Second episodes of Buruli ulcer may occur through reinfection, relapse or a paradoxical reaction. We formally demonstrated that the recurrence in these two patients was due to reinfection. Based on the sites at which the patients reported engaging in activities relating to water, we were able to identify possible sites of contamination. Our findings indicate that the non-random distribution of M. ulcerans genotypes in this region may provide useful information about activities at risk.

Overview: Mycolactone , the Macrolide Toxin of Mycobacterium ulcerans

The acquisition by a Mycobacterium marinum-like progenitor of a plasmid encoding enzymes for the biosynthesis of the highly potent macrolide toxin mycolactone has set off the evolution of M. ulcerans toward a new mycobacterial species. While the selective advantage of producing mycolactone for survival in environmental niche(s) of the pathogen is unclear, there is no doubt that the cytotoxic, immunomodulatory, and analgesic properties of mycolactone are key for the establishment and progression of M. ulcerans infections in the host. Improved procedures for the isolation, handling, and detection of the amphiphilic and light-sensitive toxin have facilitated studies to unravel molecular mechanisms of mycolactone action on host cells in vitro and on cellular and immune responses in animal models. The pivotal role of mycolactone in the pathology of Buruli ulcer and the fact that the toxin has not been associated with other pathogens make it an ideal target for therapeutics/vaccines aiming at mycolactone neutralization and for the development of assays for the diagnosis of the disease.