Yeast and Fungus Among Us: Tinea and Candida Infections of the Skin

MAY 12, 2015
Jeannette Y. Wick, RPh, MBA
Fungal infections are common but tend to resolve completely with treatment.
Fungi are ubiquitous and present in all environmental niches (eg, soil, plants, trees, indoor surfaces, human skin). There are roughly 1.5 million different species of fungi, a handful of which are responsible for the majority of unsightly, often embarrassing skin infections. The health care community began to shine the spotlight on fungal infections in the late 20th century: at that time, the spread of HIV created large populations of immunologically impaired people with heightened susceptibility to raging, potentially lifethreatening fungal infections.1,2

The Fungi Story
Fungi were originally classified as plants—think, grocery-store mushrooms— and many people are unaware that these chlorophyll- and cell wall–deficient organisms are not plant species. Most fungi thrive at temperatures between 53.6°F and 86°F (12°C-30°C). Mammals’ high body temperatures compared with ambient temperatures endow them with protective endothermy (inhospitable temperature for fungal growth) against fungi that enter the body.2

The approximately 300 fungi that cause disease in humans are primarily dermatophytes—they infect our outer skin—and they are classified by the area they infect. Fungi need warmth and moisture, making sweaty feet, skin folds, and mucous membranes attractive. Some fungi are yeast-like, causing infections such as candidiasis, while others are mold-like, causing tinea infections. This article examines the most common fungal skin infections3 (Online Table4-6).

Candida yeasts grow on the skin’s surface. Antibiotic use or immune system dysfunction creates opportunities for oral, digestive, or vaginal overgrowth. Candida fungi prefer moist areas, making Candida a common cause of diaper rash, rash in obese patients’ skin folds, and vaginal infections. Candida infection often responds to nystatin.5,6

Athlete’s Foot, Jock Itch, and Ringworm
Three types of fungal infection are closely related:
  • Tinea pedis (athlete’s foot): on any given day, 20% of Americans are infected (most of them are men). Risk factors include wearing athletic shoes that retain warmth and perspiration and using public athletic facilities. Most patients can treat athlete’s foot successfully with an OTC topical antifungal, although severe cases require a prescription product. Recurrence is common, even after prolonged treatment.6,7
  • Tinea cruris (jock itch): this infection frequently follows athlete’s foot and is characterized by burning, scaly, and itchy skin. It typically affects young males, although women can contract it, as well. Some clinicians counsel patients infected with athlete’s foot to put socks on before underwear to prevent the infection’s spread.6,7
  • Tinea corporis (ringworm—a misnomer, it’s not a worm): highly contagious, ringworm forms on the trunk or extremities, and affects more women than men. Ringworm’s vectors are shared clothing and towels, direct contact with others who are infected, and companion animals.6,7 These 3 infections usually respond to topical treatment with terbinafine, butenafine, or luliconazole. Extensive or severe infection, however, may require oral antifungals.6-8