Fungi are a type of organism that includes yeasts, molds, and mushrooms. They reproduce by spreading microscopic spores and then these spores are often present in the air, where they can be inhaled or come into contact with the surfaces of a person's body. Certain types of fungi are normally present on body surfaces or in the intestines. Although normally harmless, these fungi sometimes cause local infections of the skin and nails, vagina, mouth, or sinuses. Although, humans have a high level of innate immunity to fungi these infections are very common. Most of the infections they cause are mild and self-limiting. The term mycosis refers to conditions in which fungi pass the resistance barriers of the human body and establish infections. Mycoses are classified into several groups. During the past two decades, significant progress has been made in the management of infectious complications in patients with fungal infections.Normal resistance barriers
This resistance is due to:
1. The fatty acid content of the skin
2. The pH of the skin, mucosal surfaces and body fluids
3. Epithelial cell turnover
4. Normal flora
5. Transferrin
6. Cilia of the respiratory tract
When fungi do pass the resistance barriers of the human body and establish infections, the infections are classified according to the tissue levels initially colonized.
Risk Factors for Developing Fungal Infections
Use of immunosuppressive drugs
• Anticancer drugs (chemotherapy)
• Corticosteroids and other immunosuppressant drugs
Other diseases and conditions
• AIDS
• Kidney failure
• Diabetes
• Lung disease, such as emphysema
• Hodgkin's disease or other lymphomas
• Leukemia
• Extensive burns
• Organ transplantation
Types of mycoses
1. Superficial mycoses
These are infections limited to the outermost layers of the skin and hair. The most common are:
• Pityriasis versicolor
• Tinea nigra
• Black piedra
• White piedra
2. Cutaneous mycoses
These infections are restricted to the keratinized layers of the skin, hair, and nails. Unlike the superficial mycoses, host immune responses may be evoked, resulting in pathologic changes expressed in the deeper layers of the skin. The organisms that cause these diseases are called dermatophytes, and also ringworm or tinea. The following diseases are caused by Microsporum, Trichophyton, and Epidermophyton.
• Tinea capitis
• Tinea corporis
• Tinea manuum
• Tinea cruris
• Tinea pedis
• Tinea unguium
• Endothrix
• Ectothrix
3. Subcutaneous mycoses
These infections involve the dermis, subcutaneous tissues, muscle, and fascia.
They are often chronic and are initiated by trauma to the skin. They are extremely difficult to treat and may require surgical intervention.
The most common are:
• Sporotrichosis
• Chromoblastomycosis
• Mycetoma
4. Systemic mycoses
These infections originate primarily in the lungs and may spread too many organ systems. These organisms are inherently virulent.
5. Opportunistic mycoses
There represent the infections of patients with immune deficiencies who would otherwise not be infected. Some of those immune deficiencies are AIDS, altered normal flora, diabetes mellitus, immunosuppressive therapy, malignancy etc. They include:
• Candidiasis
• Aspergillosis
Who gets Fungal Infections?
Almost anyone can develop some kind of fungal infection. Some of these infections are contagious, which means they easily spread from person to person. For example, close contact or sharing a comb or hairbrush with someone who has tinea can spread the fungus from one person to another. Fungi need a warm, dark, and humid place to grow which is why public showers, pools, locker rooms, and even the warmth of shoes and socks can be considered the perfect environment for developing fungal infection.
Antibiotics and fungal infections
Antibiotics can also cause some kids to get a yeast infection. Even the harmless bacteria that normally fight with the yeast for a place to live are killed by antibiotics and the yeast is free to grow.
The most common fungal infections
• Tinea
Tinea is a very common type of fungal infection which is localized on the hair, skin, or nails. It is very easy to recognize the first symptoms - when it's on the skin, it usually begins as a small red area the size of a pea. It slowly grows and spreads out in a circle or ring. Tinea is often called ringworm because it may look like tiny worms are under the skin. Since the fungi that cause tinea live on different parts of the body, they are named for the part of the body they infect.
• Athlete's foot
This is another common fungal infection. It usually appears between the toes but it can also affect toenails and the bottom or sides of the feet.
• Jock itch
This is a fungal infection of the groin and upper thighs. Many people still believe that only men get it, but women can get it too.
• Candida
Candida most often affects the skin around the nails or areas around body openings: vagina, mouth etc. Diaper rash in babies is one type of Candida infection, as is thrush characterized by white patches often found in the mouths of babies. Older girls and women may develop another form of Candida infection in and around the vagina.
Treatment of fungal infections
There are several problems in treatment of fungal infections: because many of these infections develop slowly, months or years may pass before a person seeks medical attention. People that have a weakened immune system also present a problem. In them the fungal infections can be very aggressive, spreading quickly to other organs and often leading to death.There are several drugs which are effective against fungal infections, but the structure and chemical makeup of fungi makes them difficult to kill. A complete treatment often lasts for several months.
Drugs for Fungal Infections |
Drug | Common Uses | Side Effects |
Amphotericin B | Wide variety of fungal infections | Chills, fever, headache, vomiting; lowered blood potassium levels, kidney damage, anemia |
Caspofungin | Aspergillus and possibly Candida | Fever, nausea, inflammation of veins |
Fluconazole | Candida and other fungal infections, including Cryptococcus | Liver toxicity but less than that with Ketoconazole |
Flucytosine | Candida and Cryptococcus infections | Bone marrow and kidney damage |
Itraconazole | Candida and other fungal infections | Nausea, diarrhea, liver toxicity but less than that with Ketoconazole |
Ketoconazole | Candida and other fungal infections | Nausea and vomiting, blocked production of testosterone and cortisol, liver toxicity |
Voriconazole | Aspergillus and Candida | Visual disturbance |
Treatment of nail fungus
• Oral medicationsOral antifungal medication, such as Itraconazole (Sporanox®), Fluconazole (Diflucan®) and Terbinafine (Lamisil®) are prescribed in most of the cases.
They are effective because they help a new nail grow free of infection, slowly replacing the infected portion of the nail.
• Antifungal lacquer
Sometimes doctor may prefer to prescribe an antifungal nail polish, especially if the patient has problems with a mild to moderate infection of nail fungus. The FDA has approved a topical antifungal lacquer called ciclopirox (Penlac®).
• Topical medications
Sometimes the doctor may also prescribe other topical antifungal medications, such as econazole nitrate (Spectazole®). Topical medications usually don't provide a cure but may be used in conjunction with oral medications.
Vaginal candidiasis
In most cases Nystatin® tablets are used for treatment. Clotrimazole ointment is another option. Studies have shown that HIV-negative women may only have to take the drug Diflucan® one time to treat this condition.
Oral Thrush
Treatments for oral thrush include mouthwash and tablets called troches. Some people use baking soda or hydrogen peroxide mixed with water to rinse the mouth. If the thrush is advanced, this isn't likely to work. Treatments for thrush include Clotrimazole, Fluconazole, and Ketoconazole. These drugs have different brand names.
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