A 42-year-old man with poorly controlled diabetes mellitus (HbA1c 11.2%) presents with a 3-week history of progressive dysphagia and retrosternal chest pain. Endoscopy reveals white plaques in the oesophagus that do not wipe off easily. KOH mount of the biopsy specimen shows pseudohyphae and budding yeast. He has no prior antifungal exposure. Which of the following antifungal agents is the most appropriate first-line therapy for this patient?

Explanation

## Clinical Diagnosis The patient has oesophageal candidiasis, confirmed by endoscopy (non-removable white plaques) and KOH microscopy (pseudohyphae and budding yeast). The risk factor is poorly controlled diabetes. ## First-Line Antifungal for Oesophageal Candidiasis **Key Point:** Fluconazole is the gold-standard first-line agent for oesophageal candidiasis in non-immunocompromised patients. It achieves excellent oesophageal tissue penetration and has favourable oral bioavailability. **High-Yield:** Fluconazole dosing for oesophageal candidiasis is 200 mg once daily (or 100 mg daily if mild); duration is typically 14–21 days. Response rates exceed 90% in immunocompetent hosts. ## Why Fluconazole? | Feature | Fluconazole | Amphotericin B | Terbinafine | Caspofungin | | --- | --- | --- | --- | --- | | **Route** | Oral/IV | IV only | Oral | IV only | | **Oesophageal penetration** | Excellent | Good | Poor | Good | | **First-line for oesophageal candidiasis** | Yes | No (reserved for severe/refractory) | No (not active against Candida) | No (second-line) | | **Adverse effects** | Minimal | Nephrotoxicity, electrolyte loss | Hepatotoxicity, GI upset | Infusion reactions | | **Cost** | Low | High | Moderate | High | **Clinical Pearl:** Amphotericin B is reserved for severe oesophageal candidiasis, immunocompromised patients (e.g. CD4 < 50 in HIV), or fluconazole-refractory disease. Terbinafine is ineffective against Candida species (it targets dermatophytes and some moulds). Caspofungin is a second-line echinocandin for azole-resistant or intolerant patients. ## Management Summary 1. Initiate fluconazole 200 mg once daily orally 2. Optimise glycaemic control (target HbA1c < 7%) 3. Reassess in 7–10 days; if no improvement, consider endoscopy and culture/susceptibility testing 4. Counsel on oral hygiene and denture care if applicable **Warning:** Do not confuse oesophageal candidiasis with oral thrush (which may respond to topical agents like clotrimazole lozenges); oesophageal disease requires systemic therapy.