Oral Candidiasis

Oral candidiasis, also known as oral thrush, is a fungal infection of the mucous membranes in the mouth caused by Candida species, most commonly Candida albicans. This condition can present in various forms and is particularly prevalent in immunocompromised individuals, those taking certain medications, and denture wearers.

Oral candidiasis patient showing characteristic white slough on the tongue.

Classification

Oral candidiasis can be classified into acute and chronic forms. Acute forms include pseudomembranous candidiasis (oral thrush) and atrophic candidiasis. Chronic forms encompass atrophic candidiasis and hyperplastic candidiasis, which includes chronic oral candidiasis (Candida leukoplakia), candidiasis endocrinopathy syndrome, chronic localised mucocutaneous candidiasis, and chronic diffuse candidiasis.

Appearance-Based Classification

Three main clinical appearances are recognised: pseudomembranous, erythematous (atrophic), and hyperplastic. Pseudomembranous candidiasis, the most common type, is characterised by white slough that can be wiped away to reveal reddened mucosa beneath. Erythematous candidiasis presents as red, raw-looking lesions, while hyperplastic candidiasis appears as persistent white plaques that do not rub off.

Pseudomembranous candidiasis in the mouth and oropharynx.

Pseudomembranous candidiasis in a person with HIV.

Associated Lesions

Angular Cheilitis

Angular cheilitis involves inflammation at the corners of the mouth, often due to mixed infections of Candida and Staphylococcus aureus. Symptoms include soreness, redness, and fissuring.

Angular cheilitis.

Denture-Related Stomatitis

This condition affects the mucosa beneath a denture, usually an upper denture, and is associated with Candida species in 90% of cases. It is characterised by mild inflammation and erythema.

Median Rhomboid Glossitis

This is an elliptical or rhomboid lesion in the centre of the dorsal tongue, marked by depapillation and redness. It frequently involves Candida species.

Median rhomboid glossitis.

Signs and Symptoms

Oral candidiasis often presents without pain, but a burning sensation or metallic taste can occur. Pseudomembranous candidiasis rarely causes symptoms other than discomfort or a bad taste. Dysphagia may indicate oropharyngeal or esophageal involvement.

Causes

Species

Candida albicans is the most common cause, but other species like Candida tropicalis, Candida glabrata, and Candida parapsilosis can also be involved. Carriage of C. albicans is common and necessary for developing candidiasis.

Predisposing Factors

Local factors include denture wearing, corticosteroid inhalers, reduced salivary flow, and a high sugar diet. Systemic factors encompass extremes of age, endocrine disorders like diabetes, immunosuppression, broad-spectrum antibiotics, and nutritional deficiencies.

Oral candidiasis in an infant. At very young ages, the immune system is yet to develop fully.

Diagnosis

Diagnosis is often clinical but can be supported by oral swabs, smears, or biopsies stained with periodic acid-Schiff. Differential diagnosis includes conditions like lichen planus and erythroplakia.

Treatment

Topical antifungal drugs such as nystatin and miconazole are primary treatments. Underlying immunosuppression should be managed to prevent recurrence. Systemic antifungals may be necessary for immunocompromised patients. Denture hygiene is very important; disinfecting dentures with solutions like sodium hypochlorite or chlorhexidine is recommended.

Prophylactic antifungals may be used in high-risk groups. Improving oral hygiene, reducing sugar intake, and quitting smoking can reduce candidal load.

In summary, oral candidiasis is a common fungal infection with various clinical presentations and associated with multiple predisposing factors. Effective management involves antifungal treatment, addressing underlying causes, and maintaining good oral and denture hygiene.

Self-assessment MCQs (single best answer)

Which species is most commonly responsible for oral candidiasis?

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Which form of oral candidiasis is characterised by white slough that can be wiped away to reveal reddened mucosa beneath?

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What is the most likely cause of angular cheilitis?

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Which condition is associated with inflammation and erythema beneath a denture?

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What are common symptoms of oral candidiasis?

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Which factor is NOT a local predisposing factor for oral candidiasis?

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Which diagnostic method is commonly used to support a clinical diagnosis of oral candidiasis?

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Which topical antifungal drug is commonly used to treat oral candidiasis?

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Which of the following is NOT a systemic predisposing factor for oral candidiasis?

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Which measure is recommended to disinfect dentures to prevent oral candidiasis?

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