Oropharyngeal candidiasis, also referred to as oral thrush, is a fungal infection of the oral cavity and pharynx, primarily caused by the opportunistic yeast Candida albicans. It manifests as white or creamy plaques on the tongue, inner cheeks, and throat, and is often associated with discomfort, altered taste, and in severe cases, difficulty swallowing. This condition is common among immunocompromised individuals but may also occur in otherwise healthy people under specific circumstances.
Etiology and Risk Factors of Oral Thrush
Oropharyngeal candidiasis occurs when the natural balance of oral flora is disrupted, leading to overgrowth of Candida species. While C. albicans accounts for the majority of infections, non-albicans species such as C. glabrata, C. tropicalis, and C. krusei are increasingly implicated.
Key Risk Factors
- Immunosuppression (HIV/AIDS, chemotherapy, corticosteroids)
- Antibiotic use (broad-spectrum agents disrupting normal flora)
- Diabetes mellitus
- Dentures (especially ill-fitting or poorly cleaned)
- Dry mouth (xerostomia)
- Smoking
- Infants and elderly individuals
- Inhaled corticosteroids (e.g., for asthma)
Pathophysiology of Oropharyngeal Candidiasis
The transition of Candida albicans from a commensal yeast to a pathogenic hyphal form is central to disease development. This morphological shift enables tissue invasion and evasion of the host immune response.
Clinical Manifestations and Types
Pseudomembranous Candidiasis (Classic Oral Thrush)
- Creamy white patches on mucosal surfaces
- Can be wiped off, leaving erythematous base
- Common in infants and immunocompromised patients
Erythematous (Atrophic) Candidiasis
- Red, inflamed mucosa without visible plaques
- Often associated with denture use or antibiotics
Hyperplastic Candidiasis
- White plaques that cannot be wiped off
- Typically on the buccal mucosa
- Requires biopsy to rule out malignancy
Angular Cheilitis
- Cracking and redness at the corners of the mouth
- Often co-infected with Staphylococcus aureus
Diagnostic Criteria and Investigations
Diagnosis is largely clinical but may be supported by laboratory tests in unclear or persistent cases.
Clinical Examination
- Inspection for white plaques, erythema, fissures
- Assessment of predisposing factors
Laboratory Confirmation
- KOH preparation: Scraping stained with potassium hydroxide reveals budding yeasts and pseudohyphae
- Fungal culture: Identifies species and guides antifungal sensitivity
- Biopsy: Used for hyperplastic variants or when malignancy is suspected
Differential Diagnosis
- Leukoplakia (white lesions not removed by scraping)
- Lichen planus
- Herpetic stomatitis
- Aphthous ulcers
- Squamous cell carcinoma
Accurate differentiation is essential to avoid misdiagnosis and inappropriate treatment.
Antifungal Treatment Options
Treatment involves eliminating the fungal infection and addressing underlying risk factors.
Topical Antifungals (for mild to moderate cases)
- Nystatin suspension: 100,000 units/mL swish and swallow
- Clotrimazole troches: 10 mg dissolved five times daily
- Miconazole mucoadhesive tablets
Systemic Antifungals (for severe or refractory cases)
- Fluconazole: 100–200 mg daily for 7–14 days
- Itraconazole or Posaconazole: In cases resistant to fluconazole
- Amphotericin B: Reserved for resistant infections, especially in immunocompromised patients
Preventive Strategies and Management of Recurrence
Addressing Risk Factors
- Discontinuation or dose adjustment of antibiotics or corticosteroids
- Managing diabetes and dry mouth
- Improving denture hygiene and fit
- Smoking cessation
Preventive Measures
- Rinsing mouth after inhaled steroid use
- Maintaining excellent oral hygiene
- Regular dental check-ups
Recurrent candidiasis may be an indicator of systemic immunodeficiency, warranting further investigation.
Complications of Untreated Candidiasis
- Esophageal candidiasis
- Nutritional deficiencies due to painful swallowing
- Systemic candidiasis (in severely immunocompromised patients)
- Chronic mucocutaneous candidiasis
- Precursor lesions for malignancy in hyperplastic forms
Prompt treatment is essential to avoid progression and systemic involvement.
Oropharyngeal Candidiasis in Special Populations
HIV/AIDS Patients
- Frequently observed and may signal declining CD4 count
- Requires aggressive systemic antifungal therapy
- Consider prophylaxis for recurrent episodes
Infants and Neonates
- Usually benign and self-limiting
- Nystatin suspension commonly used
- Educate parents on sterilizing feeding equipment
Elderly and Denture Wearers
- Denture stomatitis and atrophic candidiasis are common
- Remove and disinfect dentures nightly
- Antifungal gel or rinse applied to dentures
Frequently Asked Questions
Is oropharyngeal candidiasis contagious?
It is not considered highly contagious under normal circumstances but may be transmitted in immunocompromised settings.
Can oral thrush go away on its own?
Mild cases may resolve spontaneously, but persistent or severe infections require antifungal treatment.
How can I prevent oral thrush while using inhaled steroids?
Rinse the mouth thoroughly with water after each use and consider using a spacer device.
What foods should I avoid with oral thrush?
Avoid sugary and acidic foods that promote yeast growth and irritate mucosal surfaces.
Is recurrence common?
Yes, especially in those with underlying immunosuppression, poorly controlled diabetes, or continued use of risk-enhancing medications.
Oropharyngeal candidiasis is a common fungal infection with varied clinical presentations and significant implications in immunocompromised populations. Accurate diagnosis, appropriate antifungal therapy, and targeted preventive strategies are essential for optimal outcomes. Clinicians must remain vigilant for recurrence and address underlying systemic conditions to ensure long-term management and prevention.
