Physiological characters of Sporothrix schenckii isolates

Sporotrichosis is endemic in three regions (east, north and south) in India. The colony morphology and physiological characteristics of 49 clinical isolates from these three regions (25 from north India, 17 from east India and seven from south India) were analysed in both mycelial and yeast forms. No difference in colony character was seen among the 49 isolates on three different media. Growth of all isolates was inhibited at 40 degrees C. The yeast forms were found to be more tolerant to osmotic pressure and salt concentrations. Most mycelial forms grew well between pH 3-12.0 whereas most yeast forms could tolerate a pH range of 2.4 to 9.5. Variations in assimilation of arabinose, dextrin, raffinose, rhamnose and starch was observed among strains from different geographical regions. The yeast forms did not show any urease activity but the mycelial forms of all isolates could split urea. Phenol oxidase and potassium nitrate assimilation were positive and gelatinase activity and casein hydrolysis were negative for all isolates.