Comparative virulence of Absidia corymbifera strains in mice

The comparative virulence of six different strains of Absidia corymbifera for cortisone-treated and untreated Swiss mice was determined. Spores of the six strains were inoculated into mice by the intravenous, intraperitoneal, and intranasal routes. All six strains were found to be virulent in cortisone-treated and untreated mice by the intravenous route. Up to a 16-fold difference in strain virulence was observed for cortisone-treated mice and up to a 10-fold difference for untreated mice. When spores were administered by the intraperitoneal route, 50% lethal dose values could be calculated only for the cortisone-treated mice, although a few deaths were seen in untreated mice challenged with 10(7) spores. Each of the six isolates of A. corymbifera, when administered in an intranasal dosage of 10(6) spores, produced death in some cortisone-treated mice. Studies made to determine the viability of spores produced by each strain revealed that germination was 90% or greater on Littman and YpSs agars at an incubation temperature of 40 degrees C in less than 12 h.