Oral thrush (mouth thrush)

Introduction
Oral thrush, medically known as oral candidiasis, is a fungal infection of the oral mucosa caused primarily by Candida albicans, although other Candida species such as C. glabrata or C. tropicalis can also be responsible. This condition is common in infants, immunocompromised individuals, and those using certain medications. It presents as creamy white plaques on the oral surfaces, which can be wiped away to reveal erythematous mucosa underneath.

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Epidemiology

• More prevalent in newborns, elderly patients, denture wearers, and immunosuppressed individuals.

• Common in patients receiving chemotherapy, radiotherapy, or long-term corticosteroid therapy.

• Higher incidence in individuals with uncontrolled diabetes or HIV/AIDS.

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Pathophysiology
Candida species are commensal organisms in the mouth in up to 50% of healthy individuals. Disease develops when host immunity is compromised or oral microflora balance is disturbed. Risk factors include:

• Immunosuppression (HIV, cancer therapy).

• Broad-spectrum antibiotics (disrupt normal bacterial flora).

• Inhaled corticosteroids (e.g., fluticasone, budesonide).

• Xerostomia (dry mouth).

• Poor oral hygiene.

• Wearing dentures overnight.

Overgrowth of Candida leads to adherence to epithelial cells and penetration of superficial mucosal layers, triggering inflammation and the typical appearance.

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Clinical Types

1. Pseudomembranous Candidiasis (most common)

• White, curd-like plaques on the buccal mucosa, tongue, palate.

• Lesions can be wiped off, leaving erythematous or bleeding mucosa.

2. Erythematous (Atrophic) Candidiasis

• Red, inflamed mucosa, often painful or burning.

• Common in denture wearers.

3. Hyperplastic Candidiasis

• White plaques that cannot be easily wiped off; rare, chronic form.

4. Angular Cheilitis

• Fissuring and redness at the corners of the mouth; often associated with mixed bacterial infection.

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Diagnosis

• Usually clinical based on appearance.

• Confirmatory tests:

  • Microscopy (KOH preparation) showing yeast and pseudohyphae.

  • Fungal culture (if recurrent or resistant cases).

  • Consider HIV testing in recurrent or severe cases without other explanation.

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Management

General Principles

• Identify and address underlying risk factors (e.g., optimize diabetes control, improve denture hygiene, rinse mouth after inhaled steroids).

• Ensure good oral hygiene.

• Remove and disinfect dentures overnight.

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Pharmacologic Treatment

1. Topical Antifungal Therapy – First-line in mild, uncomplicated cases:

• Nystatin oral suspension: 100,000 units/mL; 4–6 mL swished in mouth for several minutes, then swallowed or spit out, four times daily for 7–14 days.

• Miconazole oral gel: Apply 2.5 mL to affected area four times daily after meals for 7–14 days (avoid in infants <4 months due to choking risk).

• Clotrimazole troches: 10 mg dissolved slowly in mouth, five times daily for 7–14 days (not suitable for very young children or patients with dry mouth).

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2. Systemic Antifungal Therapy – For severe, refractory, or immunocompromised patients:

• Fluconazole:

  • Adults: 50–100 mg orally once daily for 7–14 days.

  • Severe or recurrent infection: Up to 200 mg/day.

• Itraconazole oral solution: 200 mg daily for 7–14 days; take on an empty stomach.

• Posaconazole or voriconazole: Used in resistant cases, usually under specialist care.

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3. Adjunctive Measures

• Denture care: Soak in chlorhexidine solution or antifungal solution overnight.

• Saliva substitutes in xerostomia patients.

• Probiotics (evidence limited but may help restore microbial balance).

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Special Considerations

Infants:

• Nystatin suspension: 1 mL to each cheek four times daily after feeding.

• Ensure sterilization of feeding bottles and pacifiers.

Breastfeeding mothers (if nipple candidiasis present):

• Topical miconazole or clotrimazole cream applied to nipples after each feed.

• Treat both infant and mother to prevent reinfection.

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Complications

• Esophageal candidiasis (especially in immunocompromised patients), presenting with dysphagia or odynophagia.

• Chronic hyperplastic candidiasis has a small risk of malignant transformation.

• Recurrent infections may indicate underlying systemic illness such as HIV/AIDS or uncontrolled diabetes.