(described by Cesati and de Notaris in 1861)
Taxonomic Classification
Kingdom: Fungi
Phylum: Ascomycota
Class: Euascomycetes
Order: Pleosporales
Family: Leptosphaeriaceae
Genus: Leptosphaeria
Description and Natural Habitats
Leptosphaeria is a dematiaceous (phaeoid, or dark-walled) filamentous fungus found in the soil. It grows in its teleomorphic phase. One of its species, Leptosphaeria coniothyrium has a known anamorphic growth form included in the genus Coniothyrium. Leptosphaeria is an occasional cause of human infections.
Species
Leptosphaeria currently has three defined species; Leptosphaeria coniothyrium, Leptosphaeria senegelansis, and Leptosphaeria thompkinsii. See the summary of synonyms and telemorph-anamorph relations for the Leptosphaeria spp.
Pathogenicity and Clinical Significance
Leptosphaeria spp. are the among the causative agents of human mycetoma and phaeohyphomycosis. Leptosphaeria senegalensis mycetoma is seen mostly in Central Africa.
In cases with mycetoma, black and soft grains with pale centers are observed. These grains are irregular in shape and about 1 mm in diameter [462, 531].
Macroscopic Features
Colonies of Leptosphaeria grow slowly. The texture is woolly and the front color is dark olive with a gray margin. Form the reverse, the color is dark olive to black and is again surroundered by a grayish margin [531].
Microscopic Features
Hyphae, ascomata (cleistothecia), asci, and ascospores are observed. Ascomata are without ostioles, globose to subglobose, and black in color. They carry the asci inside. Asci are clavate to cylindrical and bitunicate. Each ascus carries 8 ascospores inside. Ascospores are 4- to 9-celled, hyaline or pigmented, fusoid to curved, and with a constriction at each septum. Leptosphaeria thompkinsii forms ascospores with 6 septa and pointed ends while ascospores of Leptospheria senegalensis have 4 septa and rounded ends [531].
Histopathologic Features
See our histopathology page.
Laboratory Precautions
No special precautions other than general laboratory precautions are required.
Susceptibility
Very limited data are available. In a previous in vitro assay, ketoconazole and itraconazole MICs for Leptosphaeria thompkinsii appeared to be lower than those of econazole and miconazole [2313].
For MICs of various antifungal drugs for Leptosphaeria, see our N/A(L):susceptibility database.