Microbiology and potential virulence of Sporothrix cyanescens, a fungus rarely isolated from blood and skin

Abstract

Sporothrix cyanescens has been recovered from blood and a finger lesion at several medical centers in the United States. The morphology and physiology of these and three additional isolates were studied. S. cyanescens was distinguished from S. schencku and S. fungorum by white to lavender colonial pigmentation and from S. schenckii also by the formation of secondary conidia. Ail isolates of S. cyanescens grew well at 37°C, were cycloheximide susceptible, strongly urease positive, and benomyl resistant, failed to hydrolyze starch, and were inhibited by sodium chloride in vitro at a concentration of. 12%. Study of S. cyanescens in a murine model by using intravenous inoculation failed to demonstrate an invasive pathogenic potential. The validity of the transfer of S. cyanescens to the new genus Cerinosterus Moore is discussed.

Physiological characters of Sporothrix schenckii isolates - Physiologische Merkmale von Sporothrix schenckii-Isolaten

“…Howard and Orr reported a thiamine requirement for the growth of S. schenckii [18]. In a more extensive study, Sigler et al showed that yeast forms of S. schenckii hydrolysed urea after 96 h of incubation [19]. We found a similar result with all those isolates of S. schenckii.…”

“…Conidiation was better observed on CMA as compared to SDA and PDA. Earlier studies with environmental or clinical isolates found no significant difference in the colony characters [18][19][20]as all the isolates grew well between the temperatures of 30 and 37°C but failed to grow at a temperature of 40°C. In an earlier study it was reported that environmental isolates grew better at 30°C and even at 35°C, however, the clinical isolates grew at 37°C [18,19].…”

“…Conidiation developed quickly on CMA in comparison with SDA and PDA. In earlier studies no difference was observed in colony morphology between clinical and environmental isolates [18][19][20].…”

“…The strains in the present study, grew well in the temperature range 30-37°C, but failed to grow at a temperature of 40°C. In an earlier study it was reported that the environmental strains grew better at a temperature range of 30-35°C and the clinical isolates could grow at 37°C [18,19].…”

“…Despite being a widely distributed mycotic disease, this organism has been poorly studied with regard to its morphological and physiological characters. Few studies on optimal temperature and nutritional requirements for growth are available for environmental and clinical isolates [18][19][20].…”