The use of nutritional tests for the differentiation of dermatophytes

One hundred and forty-seven isolates distributed among 22 species of dermatophytes were tested for ability to assimilate 23 carbon sources and 4 nitrogen sources, and to hydrolyse casein, tyrosine, gelatine, starch and urea. Differences were found among species in the rate of growth on 11 of the carbon sources, 2 of the nitrogen sources and the time taken to hydrolyse urea. Based on these findings, a practical scheme allowing differentiation of the 22 species investigated is presented. Since the differences in assimilation pattern did not correlate with morphological divisions, this scheme may prove useful in situations where conventional morphological techniques fail to provide an adequate identification of an unknown isolate.