Demonstration of dermatophyte dissemination from the infected soles using the foot-press method

We have designed a new direct isolation method, the foot-press method, to survey dissemination of dermatophytes from the infected soles. A total of 56 untreated patients with tinea pedis were examined. The infected soles of 42 patients were pressed onto actidione-chloramphenicol-5-fluorocytosine (5FC)-gentamicin sulphate Sabouraud glucose medium prepared in a large culture dish; the culture media were then incubated at 25 degrees C. Dermatophytes were isolated in 30 out of the 42 patients, while no dermatophytes could be grown from 10 healthy controls. The number of isolated colonies from each patient ranged from 1 to 97 (mean+/-SD, 11+/-20). The isolation frequencies were higher in the patients of hyperkeratotic type and in those with tinea unguium, while causative organisms and the extent of the lesions did not affect the results of the foot-press method significantly. In order to reveal the morphology of disseminated dermatophytes, 1 x 1 cm pieces of culture media were cut out from culture dishes after pressing infected soles and were examined microscopically. Dermatophyte-like spores or hyphae, most of which were detached from cornified cells, could be seen in 10 out of 14 patients. Subsequently performed slide cultures isolated dermatophytes from approximately 70% of the pieces on which dermatophyte-like fungi were observed.