Cotton-Swab Method Comparable to Scrape-Culture Method for Diagnosing Tinea Capitis

The efficacy of the “cotton swab technique” for diagnosing tinea capitis in pediatric patients was supported by study data published in the Journal of the American Academy of Dermatology. Compared with the gold standard scrape-culture method, the use of a cotton swab was better tolerated by patients and easier for physicians to perform.

Investigators conducted a prospective study of pediatric patients with suspected tinea capitis. Between July 2017 and July 2019, 25 patients were recruited at the Montreal Children’s Hospital and affiliated Children’s Clinic. Patients underwent both the scrape-culture and cotton swab collection methods. For the scrape method, a glass slide was used to scrape the scalp, and another slide was used to collect scale and broken hairs. For the swab-culture method, the physician swabbed an affected scalp area with a moistened cotton tip applicator. Samples were analyzed at the hospital laboratory.

The majority (n=24; 96%) of patients were age 1 to 18 years at recruitment and approximately half (n=13; 52%) were boys. Median age at tinea capitis presentation was 3.9 years. Overall concordance between the scrape- and swab-culture methods was 100%. Both methods were able to isolate endothrix and ectothrix dermatophyte species. Compared with the scrape-culture method, the swab technique appeared to be more tolerable to patients and their parents. The scrape-culture method may cause discomfort, investigators wrote, and can be difficult to perform with an uncooperative patient. As a limitation, swabbed samples require staining in a laboratory and cannot be analyzed at the patient’s bedside.  

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As the data demonstrated, the swab-culture method was as efficacious as the existing gold standard for diagnosing tinea capitis. Investigators endorsed the adoption of the swab-culture technique to obtain samples in young patients with suspected tinea capitis.

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Le M, Gabrielli S, Ghazawi FM, Alkhodair R, Sheppard DC, Jafarian F. Efficacies and merits of the cotton swab technique to diagnose tinea capitis in the pediatric population [published online January 12, 2020]. J Am Acad Dermatol. doi:10.1016/j.jaad.2020.01.009