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Oral candidiasis, causes, types and treatment

Oral candidiasis is an opportunistic infection of the oral cavity often caused by the overgrowth of Candida, a yeast-like fungus commonly found in the gastrointestinal tract of humans, as normal skin flora and in mucous membranes.

Candida albicans (C. albicans) accounts for around 80% of infections and can colonise the cavity, either alone or in combination with non-albican species, including Candida glabrata and Candida tropicalis.

With increased availability and prescribing of broad-spectrum antibacterials (e.g. penicillins, fluoroquinolones, macrolides) and immunosuppressive agents (e.g. corticosteroids, azathioprine, methotrexate), and with increased immunosuppressive comorbidities, including diabetes, cancer and AIDS, there has been an increase in the number of reported cases of opportunistic oral Candida infections. While not life-threatening for most patients, it can cause significant patient discomfort and, in elderly or hospitalised patients, can result in significant morbidity owing to impaired nutrition.

However, in severely immunosuppressed patients, invasive and life-threatening systemic Candida infection may develop. A tertiary care hospital reported that, of their patients suffering from Candida bloodstream infection, 45% received immunosuppressive therapy.

More than half a million prescriptions for oral Candida infections are issued each year in England.

Classification:

Pseudomembranous candidiasis is the most common type and is characterised by an extensive white ‘cottage cheese-like’ film, found on the buccal mucosa, tongue, periodontal tissues and oropharynx. The plaque can usually be scraped off to expose an underlying erythematous mucosa. If thrush is associated with the use of corticosteroid inhalers, rinsing the mouth with water (or cleaning a child’s teeth if not able to rinse and spit) immediately after using the inhaler may avoid the problem. Patients should be counselled on good dental hygiene on initiation of corticosteroid inhalers.

Acute atrophic candidiasis is associated with a burning sensation in the mouth or on the tongue, and often referred to as ‘antibiotic sore mouth’, because of its association with prolonged use of broad-spectrum antibiotics. The tongue may be bright red and painful. Although this type of candidiasis is less common, diagnosis may be difficult, but should be considered in the differential diagnosis of a sore tongue, especially in a frail, older patient with dentures who has received antibiotic therapy or who is on inhaled steroids. Other conditions that may be confused with acute atrophic candidiasis include mucositis, denture stomatitis, erythema migrans, thermal burns, erythroplakia and anaemia.

Chronic presentations of oral candidiasis can occur, often with chronic inflammation associated with denture usage.

Classification:

There are several classifications of oral candidiasis, and their similarities and differences are outlined below.

Pseudomembranous candidiasis is the most common type and is characterised by an extensive white ‘cottage cheese-like’ film, found on the buccal mucosa, tongue, periodontal tissues and oropharynx. The plaque can usually be scraped off to expose an underlying erythematous mucosa. If thrush is associated with the use of corticosteroid inhalers, rinsing the mouth with water (or cleaning a child’s teeth if not able to rinse and spit) immediately after using the inhaler may avoid the problem. Patients should be counselled on good dental hygiene on initiation of corticosteroid inhalers.

Acute atrophic candidiasis is associated with a burning sensation in the mouth or on the tongue, and often referred to as ‘antibiotic sore mouth’, because of its association with prolonged use of broad-spectrum antibiotics. The tongue may be bright red and painful. Although this type of candidiasis is less common, diagnosis may be difficult, but should be considered in the differential diagnosis of a sore tongue, especially in a frail, older patient with dentures who has received antibiotic therapy or who is on inhaled steroids. Other conditions that may be confused with acute atrophic candidiasis include mucositis, denture stomatitis, erythema migrans, thermal burns, erythroplakia and anaemia.

Chronic presentations of oral candidiasis can occur, often with chronic inflammation associated with denture usage.

Angular chelitis is defined as fissuring, scaling and erythema of the corners of the mouth. It may be associated with Candida infection, but can be co-infected with staphylococcus or streptococcus bacteria, which can complicate treatment and lead to other oral bacterial infections.

Risk factors:

Reduced salivary production can predispose patients to oral candidiasis, as salivary constituents inhibit the overgrowth of Candida. Therefore, conditions reducing the amount and characteristics of saliva secretions may lead to a Candida overgrowth.

Dental prostheses, such as dentures or fillings, can create a favorable environment for the Candida organisms to latch. Topical or inhaled corticosteroids temporarily suppress the oral immune system and cause alterations in the oral flora, leading to an overgrowth of Candida.

Unbalanced dietary intake of sugars, carbohydrates and dairy products can promote Candida growth by making the oral cavity more acidic and consequently favouring the Candida organisms.

Systemic factors:

Extremes of age may predispose individuals to candidiasis owing to immature or weakened immunity, along with the variations in the Candida carriage rates.

Malnutrition, particularly in iron but also in other nutrients such as essential fatty acids, folic acid, vitamins A and B6, magnesium, selenium and zinc, is often associated with increased risk of oral candidiasis. Iron deficiency diminishes the fungistatic action of transferrin and other iron-dependent enzymes used in suppressing fungal overgrowth in the oral cavity.

Prolonged use of broad-spectrum antibiotics (e.g. co-amoxiclav), or immunosuppressants (e.g. azathioprine), alters the local oral flora by killing off bacteria and suppressing the immune system. This results in a favorable environment for Candida to grow.

Diagnosis:

Recognition of the associated lesions, such as the white plaque seen in the Figure, via an oral or oesophageal examination (i.e. examining the back of the throat) should provide a diagnosis of the more common forms of oral candidiasis (e.g. pseudomembranous candidiasis). Diagnosis can, however, be confirmed microscopically via a mucosal smear or biopsy as a Candida overgrowth, and should be considered for refractory disease or the alternative presentations of the condition. A positive microbiology result for Candida alone does not indicate a necessity for treatment as patients are routinely colonised, as aforementioned. Oral candidiasis is uncommon in healthy adults and may be the first presentation of an undiagnosed risk factor.

Treatment:

Traditionally, topical antifungals are the preferred treatment for oral candidiasis. Locally administered antifungals offer the advantage of reduced systemic exposure, which results in fewer adverse drug reactions or interactions. The British National Formulary (BNF) lists two options: nystatin and miconazole. However, the four-times-per-day administration makes patient adherence for the requisite 7–14 days challenging. Reiterating the importance of this regular administration to patients for preventing infection can help improve compliance.

(11/21/2020)
by Royal Pharmaceutical Society

More Information: https://www.pharmaceutical-journal.com/cpd-and-learning/oral-candidiasis-causes-types-and-treatment/20208483.article?firstPass=false

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