How Are Fungal Infections Diagnosed?
The diagnosis of fungal infections include the following approaches:
- Clinical findings: The diagnosis of fungal infection is usually straightforward and can be made based on clinical findings alone. Toe and nail involvement is readily identified by thickened, distorted nails and peeling, irritated skin, especially in the spaces between toes. Tinea corporis (the misnomer, “ringworm”) expands circumferentially (the “ring” in ringworm) and has a red, scaling center. In Tinea cruris (“jock itch”), more common in men than women, fungus colonizes in the crural folds of the groin area.
- KOH microscopic exam: In dermatophyte infections of the nails or skin, confirmation is via a microscopic examination of skin or nail scrapings to identify the fungal branches–hyphae–that are more easily seen when potassium hydroxide (KOH) is used to make them stand out against the usual background of other cells, bacteria, and other debris.
- Culture: Fungal culture is another method of confirmation and identification of fungal species.
- IGE testing: In patients with asthma, hypersensitivity pneumonitis, or rhinosinusitis, testing for immunoglobulin IgE can be done to identify fungus as the cause.
- Additional diagnostic steps: For extensive excoriations, a gram stain and bacterial culture are helpful to identify a bacterial “superinfection” complicating the area compromised by the fungus. Such combined infections (fungus and bacteria) lead to treatment failure when only one or the other is suspected and treated.
- Precautionary testing: Except for the common nuisance dermatophyte infections of skin and nails, it is unusual to suffer a fungal infection unless one is immunocompromised. Those who suffer extensive, frequent, and severe dermatophyte infections, or who have unusual fungal manisfestations such as thrush, frequent vaginitis, fungus balls, pneumonitis, etc., should be screened for diabetes, HIV, malignancy, and other immunosuppressive illness. Those who are known immunosuppressed patients–transplant, chemotherapy, or rheumatic disease patients–should consider immediate and/or prophylactic treatment with systemic antifungals.