What Are Fungal Infections?
Fungus (pl., fungi) is a unique branch of life consisting of microscopic spore-forming organisms. Most do not cause infections, but exposure to some fungi can cause infections and allergic reactions. A type of fungus, collectively called dermatophytes, can infect the skin and nails; in immunocompromised persons, Candida, Aspergillus, and others can cause infections in the blood, lungs, and brain.
Fungi produce toxins, mycotoxins, which can be ingested in moldy food. Aflatoxin, linked to illness and cancer, can contaminate even non-peanut foods via contamination with Aspergillus from the soil.
Infections from Dermatophytes
- Tinea corporis: infection of the body in parts other than the feet, groin, or scalp. When contracted from animals such as puppies or kittens, it can be extremely irritating.
- Tinea pedis: foot.
- Tinea cruris: groin.
- Tinea capitis: scalp, primarily in children.
- Tinea unguium: nails, called onychomycosis.
Severe or frequent infections of any fungus should prompt investigations to rule out immunocompromise or diabetes.
Other Fungus-Related Illness
- Asthma: From hypersensitivity to fungal allergens.
- Allergic rhinitis: From common outdoor molds.
- Pneumonitis: A hypersensitivity to fungus in occupational settings, showers, air conditioning, and humidifiers.
- Fungus balls: Usually from Aspergillus, causing collections of the branching fungal mycelia (amassed as fungus balls) in the sinuses, lungs, kidneys, or brain.
- Candida oropharyngitis (thrush) and vaginitis (vaginal candidiasis).
Complications of Fungal Infections
Intertrigo: intertriginous dermatitis is a common inflammation that erupts in skin folds, with erythema, itching, and an unpleasant odor. Especially in those who are overweight, moisture and friction work synergistically to establish an ideal growing environment for fungus. These areas, because of the limited air exposure, can become secondarily infected with bacteria.
Opportunistic Fungal Infestions
In those who are immunocompromised (transplant, AIDS, and cancer patients), opportunistic fungal species can successfully invade and take root in the blood, lungs, and brain.
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.
How Can Fungal Infections Be Managed?
Both prevention and pharmacological treatment are equal partners in patients who have fungal infections. For treatment, there are many antifungal medications available, both topical and systemic.
Topical Management and Therapy
For superficial skin involvement with the dermatophytes (T. capitis, T. corporis, T. cruris, and Tenia pedis), antifungal sprays, powders, and solutions containing azoles, allylamines, butenafine, ciclopirox, and tolnaftate can be used. These are available in various prescription and over-the-counter commercial products and many have systemic versions for widespread or severe involvement.
- Azoles: fluconazole (Diflucan) , itraconazole (Sporanox), voriconazole (Vfend), posaconazole (Noxafil), isavuconazole (Cresemba), and ketoconazole (Nizoral).
Hepatotoxicity can occur with systemic azoles, so therapy should be accompanied by liver function studies.
- Allylamines: naftifine 2% cream (Naftin) and terbinafine 1% cream (Lamisil)
- Ciclopirox (Ciclodan, Loprox)
- Butenafine (Lotrimin)
- Tolnaftate (LamISIL, Tinactin)
Systemic Management and Therapy
Many of the active ingredients in the topical antifungal preparations have systemic counterparts that can be used when indicated, but with caveats:
- Nail involvement (onychomycosis): due to dermatophyte infections and Candida esophagitis as a complication of thrush are difficult to successfully treat with topical preparations. Systemic antifungal approaches are typically used. Nail involvement (T. unguium onychomycosis) has better success with systemic terbinafine (LamISIL) than griseofulvin (Grisfulvin); griseofulvin also has the disadvantage of requiring prolonged courses that increase the risk of hepatotoxicity and side effects.
- Azoles: cannot be used in pregnancy during the first trimester, since they are teratogenic. Amphotericin B is the suggested alternative.
- Hepatotoxicity: Concerns should prompt pre-therapy, concomitant, and post-therapy liver function testing with systemic antifungal therapy, especially when it is prolonged.
Antifungal therapy is associated with GI upset, rashes, and–specifically with the azole, voriconazole–unusual visual disturbances and photosensitivity. Rarer side effecs include headaches, dizziness, and unusual tastes in the mouth.
How Can I Prevent Fungal Infections?
Treatment and prevention are equal partners in eradication present and recurrent fungal infections. Fungus does not ordinarily infect persons in excellent health, but it seizes the opportunity for colonization in areas that are dark, moist, and hypoxic, such as intertriginous skin (skin folds) and spaces between the toes.
Prevention is centered on denying fungus organisms these opportunities:
- Daily cleansing of skin folds: including under the breasts in women and in obese men, and between the toes. Thorough drying of these areas is mandatory to eliminate the most important factor that encourages fungal growth–moisture. Drying between the toes after showering is the single, best way to prevent tinea pedis/unguium.
- Ventilation/aeration: Of affected areas as much as possible.
- Absorbent fabrics that also breathe: Such as cotton, especially to separate skin folds.
- Daily drying powders: Many of these absorbents contain antifungal ingredients as well.
- Avoid public facilities, showers, etc., barefoot.
- Treatment of hyperhidrosis.
- Weight management: Treatment for obesity reduces the amount of exposure of intertriginous skin to approximation and friction.
- If there are co-factors such as diabetes: strict glycemic control.
- Avoid scratching pruritic areas to avoid tissue damage that could serve as a nidus for bacterial superinfection.