Scopulariopsis brevicaulis: a keratinophilic or a keratinolytic fungus?

The morphologic expression of human hair and nail invasion in vitro by Scop ulariopsis brevicaulis isolates was studied by light microscopy on whole ma terial and on semi-thin sections, and also by scanning and transmission ele ctron microscopy. Only three isolates of the nine that were examined were k eratinolytic, capable of both attacking keratinic substrates and demolishin g their keratin. The process showed all the characteristic of enzymatic dig estion and was in agreement with the biochemical and morphogenetic scheme p roposed for other keratinolytic fungi during their invasion of human hair i n vitro. All the active isolates were capable of developing structures rela ted to surface erosion and radial penetration contemporaneously. However th e extent and rate of keratinolysis were rather low when compared with the e fficiency of other keratinolytic fungi. This finding suggests that S. brevi caulis is of secondary importance in the mineralization of keratinic substr ates in natural environments. From the medical standpoint the mere demonstr ation of keratinolytic activity means that it may be regarded as a real cau se of primary infection.