The FP told the patient that he had ulcerative tinea pedis related to a bacterial superinfection. The FP performed a potassium hydroxide (KOH) preparation, which was positive for branching septate hyphae. (See a video on how to perform a KOH preparation.) The small ulcerations and crusts were due to a bacterial superinfection on top of the standard tinea pedis.
Ulcerative tinea pedis is uncommon and, thus, is not always mentioned when describing the standard types of tinea pedis (interdigital, moccasin distribution, and vesicular [vesiculobullous]). Ulcerative tinea pedis does not have to have large ulcers, but there is usually disruption in the skin barrier along with signs of bacterial superinfection (such as crusting and exudate).
This patient demonstrated these signs and the FP chose to treat the patient with an antibiotic that would cover typical skin organisms. There was no need for a culture, as it was likely to grow out many types of skin flora found on the foot. This case was unlikely to be the result of methicillin-resistant Staphylococcus aureus, so a first-generation cephalosporin was adequate.
The FP treated the patient with oral terbinafine 250 mg/d for 2 weeks, along with a course of oral cephalexin 500 mg 3 times daily for one week. Three weeks later, the skin on the patient’s feet was clear, except for some postinflammatory hyperpigmentation that was likely to fade over time.
Photos and text for Photo Rounds Friday courtesy of Richard P. Usatine, MD. This case was adapted from: Usatine R, Reppa R. Tinea pedis. In: Usatine R, Smith M, Mayeaux EJ, et al, eds. Color Atlas of Family Medicine. 2nd ed. New York, NY: McGraw-Hill; 2013:799-804.
To learn more about the Color Atlas of Family Medicine, see: www.amazon.com/Color-Family-Medicine-Richard-Usatine/dp/0071769641/
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