ALSO CALLED oropharyngeal candidiasis, thrush is an infection of the mouth caused by Candida fungi. Most cases are caused by an overgrowth of Candida that normally live on the skin or mucous membranes. Overgrowth is most likely to occur in patients who are immunocompromised and in those who've recently taken broad-spectrum antibiotics, which may kill off bacteria that normally keep Candida in check. Other risk factors for thrush include use of inhaled or systemic steroids, wearing dentures or orthodontic appliances, diabetes mellitus, and advanced age.
Not all thrush originates with the patient's own flora. Hospitalized patients may become infected from cross-contamination via caregivers' hands or poorly disinfected multiuse equipment.
Besides thrush, candidiasis can cause diaper rash in infants, vaginal yeast infections in women, and systemic infection or sepsis, primarily in immunosuppressed patients. These conditions are beyond the scope of this article.
Recognizing signs and symptoms
Thrush is often asymptomatic, but it can also be characterized by a burning sensation in the mouth initially and white patches on the mucosa and tongue that resemble cottage cheese (see the illustration). Although the patches may be painless, they bleed easily when rubbed and the patient may report a bad taste in his mouth. If the infection extends into the esophagus, he may experience severe pain (especially when swallowing), excessive saliva production, drooling, malaise, and appetite loss.
Thrush is usually diagnosed on the basis of visual examination and patient history. If the patient doesn't respond to treatment, the health care provider may order a KOH (potassium hydroxide) preparation test to confirm the diagnosis. This involves taking a specimen from a white patch in the patient's mouth or throat, placing it on a slide with potassium hydroxide, and heating the slide. Skin cells in the specimen dissolve, leaving behind fungal cells that can be seen under a microscope.
In people who are in good general health, thrush is usually a minor problem that responds quickly to treatment. But in patients who have trouble fighting infection because of a chronic illness or the use of drugs that impair the immune system, thrush can be recurring and potentially life-threatening. Candida can enter the bloodstream from an oral lesion or through a systemic port of entry such as an I.V. line, causing sepsis. Unless treated aggressively, a systemic fungal infection is likely to be fatal.
Cleaning house in the mouth
Thrush in adults is typically treated with nystatin suspension (Mycostatin) q.i.d. for up to 14 days, or nystatin oral lozenges four or five times daily for up to 14 days. Use these guidelines to teach a patient about his treatment.
- Tell him to make sure his mouth is empty before he takes the drug.
- If he's taking the oral suspension, teach him to hold it in his mouth and swish several times before swallowing.
- If he's taking an oral lozenge, tell him to let it dissolve slowly in his mouth and warn him not to chew or swallow it before it dissolves.
- Teach him to complete the course of treatment as prescribed, even if symptoms clear up.
- If appropriate, advise him that overusing mouthwash or wearing poorly fitting dentures may predispose him to future thrush episodes. Teach him to clean dentures regularly.
SELECTED WEB SITES
Centers for Disease Control and Prevention: Oropharyngeal Candidiasis, http://www.cdc.gov/ncidod/dbmd/diseaseinfo/candidiasis_opc_g.htm
End of Life/Palliative Education Resource Center, http://www.eperc.mcw.edu, (search “Fast Facts” for Fast Fact and Concept #147)
Last accessed on October 6, 2006.