Thrush (Candidiasis)is a superficial yeast infection of the mouth and throat. Other names for this common condition include oral candidiasis, oropharyngeal candidiasis, pseudomembranous candidiasis, and mycotic stomatitis. Thrush is characterized by the presence of thick, curd-like white patches on the tongue and inside of the cheeks. The underlying tissue is red and inflamed. The roof and floor of the mouth and the gums may also be affected. Thrush may be easily diagnosed by the appearance of the lesion. To confirm the diagnosis, a sample for microscopic analysis may be taken by scraping the lesion with a tongue depressor.
Thrush itself is a harmless infection; however, Candida may spread throughout the body (systemic infection) to the kidneys, lungs, joints, bones, and brain and spinal cord (central nervous system). A systemic infection can be very serious, especially in a cancer patient with a weakened immune system.
Causes
Thrush may be caused by several different species of Candida. Thrush rarely occurs in healthy persons. Three factors contribute to infection Candida: impairment of the immune system (immunosuppression), injury to the tissues
(mucosa, mucous membranes) of the mouth, and decrease in saliva flow. In addition, thrush can occur following treatment with antibiotics, when normal mouth (oral) bacteria have been eliminated allowing for over-growth of Candida. In addition to standard intravenous chemotherapeutic agents, corticosteroids, cyclosporine A, and interleukin-2 suppress the immune system, placing the patient at a higher risk of infection. Patients who have been treated with myeloablative therapy, as in preparation for bone marrow transplantation, are at a very high risk of infection. In addition, certain cancers predispose the patient to developing candidiasis, including multiple myeloma, chronic lymphocytic leukemia, hairy cell leukemia, Hodgkin's disease, and adrenal tumors. Malnutrition, which is not uncommon among cancer patients, also suppresses the immune system.
Patients undergoing chemotherapy and/or head and neck radiation are at an increased risk of developing thrush. These therapies target the rapidly dividing cancer cells. The mucosal cells which line the mouth are also rapidly dividing. The skin and mucous membranes make up the first line of defense against invading organisms and, when damaged by cancer treatments, these tissues become susceptible to infection. Chemotherapy can decrease the number of neutrophils, a type of white blood cell, causing a condition called neutropenia. Neutropenia significantly increases the patient's risk of infection. Radiation therapy reduces the number of white blood cells which impairs the immune system.
Thrush is a temporary side effect of cancer treatment. It can take up to a year for the immune system to recover from intensive radiation therapy. Thrush that is related to the cancer may be persistent or recurrent.
Treatments
Thrush is usually treated with the antifungal drugsclotrimazole, nystatin, or amphotericin. Clotrimazole is taken as a lozenge which is allowed to dissolve slowly in the mouth. The commonly used nystatin is taken as a solution that is swished through the mouth, although recent studies have shown that nystatin may not be as effective as the newer antifungals. Amphotericin is taken as a tablet or solution. The duration of treatment may range from five to 14 days. Often, thrush resolves with local treatment alone, however, systemic medication (such as fluconazole) may be used in some cases.
The patient with thrush should faithfully conduct a daily oral hygiene routine consisting of tooth brushing two to three times, flossing once, utilizing medicated rinses as prescribed by the physician. Brushing and flossing should be performed carefully to prevent damage to the weakened oral mucosa. Dentures and other mouth appliances, which can harbor the yeast and be a source for possible reinfection, need to be disinfected.
Alternative and complementary therapies
Because there is the risk that Candida may spread and cause a serious systemic infection, thrush should be treated with antifungal drugs. The patient with thrush can help fight the infection by eating a well-balanced diet to counteract immunosuppression caused by malnutrition. Nutritional supplements may also be useful. Some practitioners claim that herbs (such as goldenseal or garlic) can be used to kill yeasts and boost the immune system. However, these complementary therapies should be discussed with the patient's physician because of thrush's potentially serious threat to the cancer patient.
