Isolation of herpotrichiellacious fungi from the environment

Abstract

Herpotrichiellaceous fungi, common agents of chromoblastomycosis and phaeohyphomycosis, were searched in samples of rotten wood, leaf littler, bark and soil of the rhizosphere, collected in the Centro Nacional de Pesquisas de Florestas/EMBRAPA, Colombo, PR, Brazil. Morphological analyses of macro, optic and scanning electron microscopy, as well as the determination of the nutritional pattern of the isolated strains were carried out for a taxonomical study. In a total of 17 colonies, 3 isolates (17.6%) were identified as species of medical relevance: Cladophialophora bantiana (Sacc.) de Hoog et al., Fonsecaea pedrosoi (Brumpt) Negroni and Phialophora verrucosa Medlar. The identifications were based on the results of the analyses and on the comparison with CBS (Centraal Bureau voor Schimmelcultures) reference strains. This investigation revealed the saprophytic existence of species known as agents of chromoblastomycosis and phaeohyphomycosis. These diseases are considered autochthonous in the studied area.

Chromoblastomycosis

“…In nature, monoaromates are found in trace amounts in plant debris, thorns, and wood cortex, which provide microhabitats for these fungi (74). There is a strong correlation between the traumatic implantation of potential natural sources of infection and CBM lesions (74)(75)(76)(77)(78)(79)(80). This route of infection may be supported by clinical reports of patients exhibiting the presence of fragments of plant material at the site where they experienced a previous trauma.…”

“…Ruben et al and Fernández-Zeppenfeldt et al reported the identification of Cladophialophora in cactus plants (83,89), but de Hoog et al showed that this was a molecular sibling, C. yegresii (33). Vicente et al reported the identification of mainly saprobic Fonsecaea species such as F. minima and F. erecta in plant thorns close to the habitat of patients with CBM due to F. pedrosoi, while pathogenic strains were recovered only exceptionally (56,74,76). In 1937, Conant thought that Cadophora americana recovered from wood pulp was identical to Phialophora verrucosa, which potentially caused CBM (90), but recently, Feng et al proved that the P. verrucosa complex contains clinical species next to environmental species (91).…”

“…In 1937, Conant thought that Cadophora americana recovered from wood pulp was identical to Phialophora verrucosa, which potentially caused CBM (90), but recently, Feng et al proved that the P. verrucosa complex contains clinical species next to environmental species (91). Phenotypically identified isolates of F. pedrosoi and C. carrionii have been isolated from plant debris, grass, tree cortex, and also abandoned wasp nests (75)(76)(77)(78)(92)(93)(94)(95)(96)(97). After the isolation of a strain identified as F. pedrosoi from a spiny plant (Mimosa pudica), Salgado et al suggested that it might be a probable natural source of CBM infection in the north of Brazil (74), but molecular proof was not provided.…”

“…Methods are available to isolate saprobic fungi from the environment, but selective methods for pathogens are needed. The use of mammalian vectors, as done previously by Gezuele, Mok, and others, should be repeated with the support of state-of-the-art identification methods (74)(75)(76)(77)(78).…”

Bacillus subtilis induces morphological changes in Fonsecaea pedrosoi in vitro resulting in more resistant fungal forms in vivo

“…Dematiaceous fungi are saprobes found mainly in soils and organic matter functioning as decomposition agents (15). A natural characteristic of these microorganisms is their dark cellular pigment, which is the result of a melanization process.…”