Use of the cotton swab method in diagnosing tinea capitis

Objective. To evaluate the accuracy of the cotton swab technique for identi fying fungal infections of the scalp. The purpose of the study was: 1) to c ompare the cotton swab technique with the toothbrush method, a popular and reliable means for obtaining specimens; and 2) to ascertain if transport of a specimen, entailing variable transport duration and conditions, impairs the sensitivity and specificity of the technique. Materials and Methods. Part 1 consisted of a prospective, investigator-blin ded comparison analysis. Fifty children with scalp findings suspicious for tinea capitis were cultured using both techniques: the toothbrush and cotto n swab. Ninety-six culture results were obtained for analysis. The second p art of the study consisted of a prospective comparison analysis of cotton s wab culture results obtained from samples plated immediately after collecti on in the physician's office as compared with samples transported to outsid e laboratories for processing. Thirty-one children with presumed tinea capi tis were cultured twice with the cotton swab technique; one sample was imme diately plated onto fungal medium and the other sent to an outside lab, the selection of which was dictated by the patient's insurance plan. A total o f 62 samples were obtained; 58 sample results were used for analysis. Results. In part 1 of the study, 60% of the 48 children analyzed had positi ve fungal cultures. Eighty percent of these were Trichophyton species. Ther e was 100% agreement in the results obtained; all patients with positive re sults using the toothbrush method were also positive when the cotton swab m ethod was used. Similarly, there was complete concordance in laboratory res ults from the second part of the study. Fifty percent of the 28 children an alyzed had positive cultures; 86% grew Trichophyton species. All patients w ho had positive cultures from those samples plated in-office also had posit ive results from the outside laboratory samples. Conclusions. The cotton swab technique is an easy, atraumatic, inexpensive, and reliable means to evaluate patients with suspected tinea capitis. The method remains sensitive and specific even when transport of these specimen s is required and processing is thus delayed. This painless technique requi res little technical expertise and can be rapidly performed with a standard cotton tip applicator. It should prove an invaluable aid to practitioners in evaluating patients with possible fungal infections of the scalp.