Clinical isolates. Two collections of samples were investigated in this study.
Nail specimens were collected as subungual scrapings, clippings, or curettings.
The first sample (called “strain sample” in Table 1) was a collection of 66 test
isolates obtained from serial patients who were microscopically positive and had
grown a culture in procedures for diagnosis of onychomycosis. This collection
might be biased against T. interdigitale, which is more often associated with
microscopy-negative samples than T. rubrum is. The second sample (called “nail
sample” in Table 2) was collected from 195 successive patients whose abnormal nails were indicated for dermatologic mycology evaluation. To allow valid statistical
testing, specimens from all patients in this series were included in the
sample, regardless of whether or not a positive culture or microscopy result was
obtained. Of the 261 patients, 101 were from Greece and the remainder were
Bulgarian residents. Sixteen patients suffered from suspected fingernail mycosis;
the rest were evaluated for toenail onychomycosis.
A single specimen was analyzed from each of the 261 patients. Patients were
recalled when a nondermatophyte mold grew in culture, regardless of whether or
not a dermatophyte also grew. For those patients, three independent, serial
specimens were analyzed.