Direct KOH microscopy of the skin scraping and hair shafts can confirm infection when positive, but false negatives are common even with experienced examiners. Wood's lamp examination can help identify Microsporum species, but Trichophyton species, which are increasingly common in the United States, do not fluoresce under a Wood's lamp. If necessary, fungal culture can be obtained (using a toothbrush or cotton swab) and then inoculated onto a fungal culture medium. The cotton-swab method is performed by moistening a sterile cotton swab and vigorously rubbing it over the affected areas of the scalp.