Although Mycobacterium ulcerans, M. marinum, and M. haemophilum are closely related, their exact taxonomic placements have not been determined. We performed gas chromatography of fatty acids and alcohols, as well as DNA-DNA hybridization and 16S rRNA gene sequence analysis, to clarify their relationships to each other and to M. tuberculosis. M. ulcerans and M. marinum were most closely related to one another, and each displayed very strong genetic affinities to M. tuberculosis; they are actually the two mycobacterial species outside the M. tuberculosis complex most closely related to M. tuberculosis. M. haemophilum was more distinct from M. ulcerans and M. marinum, and it appeared to be as related to these two species as to M. tuberculosis. These results are important with regard to the development of diagnostic and epidemiological tools such as species-specific DNA probes and PCR assays for M. ulcerans, M. marinum, and M. haemophilum. In addition, the finding that M. ulcerans and M. marinum are more closely related to M. tuberculosis than are other pathogenic mycobacterial species suggests that they may be evaluated as useful models for studying the pathogenesis of M. tuberculosis. M. marinum may be particularly useful in this regard since strains of this species grow much more rapidly than M. tuberculosis and yet can cause systemic disease in immunocompromised hosts.

Differentiation of Mycobacterium ulcerans, M. marinum, and M. haemophilum: Mapping of Their Relationships to M. tuberculosis by Fatty Acid Profile Analysis, DNA-DNA Hybridization, and 16S rRNA Gene Sequence Analysis

The Pathology of Mycobacterium Ulcerans Infection

We describe a series of 96 cases of Mycobacterium ulcerans infection (Buruli ulcer) from a new endemic focus in the Afram valley, north of Agogo, in Ghana. 63 cases were children under 13 years old. Active treatment by excision and skin grafting necessitates long stays in hospital and repeated procedures. Scarring and contracture are frequent. Eyes and other vital organs may be destroyed. In its endemic foci Buruli ulcer is a serious health burden on rural populations. Research is urgently needed, especially in prevention and non-surgical management.

Mycobacterium ulcerans infection in Ashanti region, Ghana.

Although Mycobacterium ulcerans elicits extensive necrosis of human skin and subcutaneous tissue, the specific cause of the necrosis has never been elucidated. In an attempt to define a toxic substance, 18 strains of M. ulcerans were inoculated into mice, and the progress of each infection was observed and compared with infections of other mycobacteria, including M. cheloni, M. marinum, and M. bovis. Culture filtrates and viable organisms of each of these mycobacteria were inoculated onto tissue culture cells. Inoculation of mouse footpads with M. ulcerans resulted in progressive infections, leading to ulceration and eventual death. Strains of M. cheloni, M. marinum, and M. bovis did not produce progressive infections in the mice. Culture filtrates of M. ulcerans produced severe cytopathogenic effects on tissue cells, but washed, viable organisms of the same strains had no cytopathogenic effect. Culture filtrates and viable organisms of M. cheloni, M. marinum, and M. bovis did not produce a cytopathogenic effect on the tissue cells. Viable organisms of selected strains of M. ulcerans and the culture filtrates of the same strains were inoculated into guinea pig skin. The culture filtrates and the viable organisms both caused focal necrosis and focal inflammation, changes that resemble those in the naturally occurring infection in man. Preliminary purification of the culture filtrate by ultrafiltration indicates that the toxic fraction has a molecular weight of approximately 100,000, and temperature studies indicate that the toxic fraction is heat labile.

https://iai.asm.org/content/iai/9/6/1114.full.pdf

S.H. Kok

Papers

Mycobacterial skin ulcers in Nigeria