Observations on strains ofFusarium solani, F. oxysporumandCandida parapsilosisfrom ulcerated legs

Abstract

Fusarium solani and F. oxysporum isolates from the moist skin surrounding chronic venous ulcers of the leg were not pathogenic to pea, wheat or tomato (one variety of each plant). However, their temperature preference, measured by radial growth rate, was only slightly above that of isolates from pea roots. An isolate of F. solani from mycotic keratitis (F. solani K) markedly preferred the higher temperatures tested. At Water Activity (Aw) 1·0 (i.e. Relative Humidity 100%) Fusarium isolates from all sources freely utilised autoclaved callus as sole source of nutrient, but F. solani K did so in a different manner from the other isolates. Neither Candida parapsilosis nor C. albicans grew on the substrate freely. None of the fungi grew on callus at Aw 0·85, but at Aw 0·92 some growth of Fusaria took place, especially in the epithelial pearls; at Aw 0·97 mycelial fronds were formed. Histology of affected skin from around leg ulcers suggested that none of the fungi attacked keratinised cells in vivo.