Candidiasis (Thrush)

Common Form of Candidiasis

Candidiasis is a fungal or yeast infection that can affect many regions of the body.  For the purpose of this discussion we will focus on the most common fungal infections  of the oral cavity. Most oral fungal infections are caused by Candida albicans however, there are several other species of Candida that could be the source of the infection. These include Candida tropical, Candida krusei, Candida parapsilosis, Candida glabrata, to name a few.

Candida albicans is an organism that resides in the oral cavity of the majority of healthy individuals. Most times the relationship between Candida and the host is one of commensalism, or a state where one organism benefits from the other without affecting it. Local or systemic factors that affect the host can lead to a pathogenic or disease state.

Candida infection is usually superficial affecting the oral mucosa or the skin.  Individuals that are severely debilitated or immunocompromised as in untreated AIDS, the infection can extend to the esophagus, bronchopulmonary tract, and other organ systems.  When treating a mild bacterial infection with broad spectrum antibiotics an opportunistic nature of the organism is observed.

There are numerous forms of oral manifestations that exist.  The most common form is thrush, or acute pseudomembranous form. Young infants and the elderly are frequently affected. The infection is common in individuals being treated with chemotherapy or radiation for leukemia.  The acute pseudomembranous form is also prevalent in individuals infected with HIV or untreated AIDS.

Acute candidiasis lesions found in the oral cavity are identified by white, soft to gelatinous plaques or nodules.  The plaque can be wiped off leaving an erythematous (red), ulcerated, raw surface that is often tender.  Even though thrush can present itself in any location, the most common locations include buccal mucosa (cheek area), oropharynx (throat), lateral aspects of the tongue.  In the majority  of cases the symptom of the infection are minimal.  In severe cases burning, tenderness, and dysphagia or difficulty swallowing can occur.

Untreated acute pseudomembranous candidiasis can eventually lead to the loss of the “pseudomembrane”, which presents itself as a generalized red lesion.  This stage of the disease is called atrophic candidiasis. Oral symptoms in atrophic candidiasis such as burning, and pain are much more pronounced due to numerous erosions and intense inflammation of the mucosal tissue.  This form of Candidiasis is also  observed with the use of broad spectrum antibiotic or multiple narrow spectrum antibiotic.  In these cases improvement can be noted with good oral hygiene practices and discontinuing the use of the offending antibiotic.

Chronic atrophic candidiasis is prevalent in individuals who wear complete maxillary dentures. Factors contributing to the development of chronic atrophic candidiasis include but are not limited to poor fitting denture, improper bite, poor oral hygiene and failure to remove the prosthesis at night.  Clinical appearance is usually bright red, velvety to pebbly surface.

Another condition commonly seen in patients with chronic atrophic candidiasis is angular cheilitis.  This condition is more prevalent in individuals who demonstrate deep folds at the commissures (angeles) of the lips, usually due to overclosure.  This creates an environment suitable for yeast colonization and proliferation.  Clinically angular cheilitis lesions are moderately painful, eroded, and encrusted.  This condition can also occur in individuals that habitually lick their lips.

Circumoral type of atrophic candidiasis can develop in individuals with severe lip-licking habits. This form of candidiasis can extend to the skin surrounding the lips.  The skin is fissured and shows up as a brown discoloration on a slightly red base.

Treatment of Acute Candidiasis

Most oral Candida albicans (yeast) infections can be treated with topical applications of nystatin suspension.  In individuals where the fungal infection is caused by an oral prosthesis, nystatin cream can be used on the affected tissue as well as the denture itself to provide a prolonged contact between the antifungal and the affected tissue. If the individual is currently being treated with broad spectrum antibiotics, withdrawing the antibiotic usually produces resolution.  Discontinuing the use of any oxygenating agents, such as hydrogen peroxide,  will lead to reestablishment of normal oral bacterial flora and relief of symptoms.   Another effective treatment often used is the administration of clotrimazole in a lozenge or troche form.   Treatment with nystatin or clotrimazole should continue for minimum of a week after clinical manifestation of the disease disappear.  It is important to mention that oral antifungals can contain a considerable amount of sugar.  Long term use of these substances, especially in individuals with xerostomia (dry mouth) can lead to increase incidence of dental caries.

Treatment of Chronic Candidiasis

Topical antifungal agents may not be effective in cases of chronic mucocutaneous  candidiasis or oral candidiasis. In these cases the use of systemic antifungal agents is indicated.  Some of these include: amphotericin B, ketoconazole (Nizoral), fluconazole (Diflucan), miconazole (Monistat), and itraconazole (Sporanox).  Use caution when taking these systemic medications because they can be hepatotoxic.

The prognosis for  treatment of acute or chronic candidiasis is very good.  It is important to note that even if the condition is successfully treated, if the underlying cause of the condition is not eliminated, untreated AIDS,  poor oral hygiene, continual wearing of a denture, or continual use of broad spectrum antibiotics, the yeast infection can recur.