A 28-year-old man with HIV/AIDS (CD4 count 45 cells/µL) is admitted with oral white plaques that cannot be scraped off easily and dysphagia. Candida species is suspected. Which Candida species is the most common cause of oesophageal candidiasis in this patient?

Explanation

## Most Common Candida Species in Oesophageal Candidiasis **Key Point:** Candida albicans is the most frequent cause of oesophageal candidiasis in immunocompromised patients, accounting for >90% of cases, even in advanced HIV/AIDS. ### Candida Species Distribution in Oesophageal Infection | Species | Prevalence | CD4 Threshold | Geographic Variation | Azole Resistance | |---------|------------|---------------|----------------------|------------------| | **C. albicans** | >90% | <50 cells/µL | Universal | Low (5–10%) | | C. glabrata | 5–10% | <50 cells/µL | Increasing in developed countries | Moderate–High (20–40%) | | C. dubliniensis | 2–5% | <50 cells/µL | More common in Europe | Low | | C. auris | <1% | <50 cells/µL | Emerging in healthcare settings | High (>90%) | **High-Yield:** Oesophageal candidiasis is an AIDS-defining illness (CDC category C) and typically occurs when CD4 count falls below 50 cells/µL. C. albicans remains the dominant pathogen regardless of geography or antiretroviral era. **Clinical Pearl:** The patient's CD4 count of 45 cells/µL and dysphagia with oral plaques are classic for oesophageal candidiasis. Initiation of antiretroviral therapy (ART) and fluconazole prophylaxis/treatment are standard interventions. ### Pathophysiology in Advanced HIV 1. **Severe immunosuppression:** CD4 <50 cells/µL eliminates T-cell–mediated immunity, allowing C. albicans overgrowth. 2. **Mucosal barrier breakdown:** Loss of Th17 responses impairs antifungal defences at the oesophageal mucosa. 3. **Virulence expression:** C. albicans upregulates hyphal formation and protease secretion in the oesophageal microenvironment. **Mnemonic:** **OECA** = **O**esophageal candidiasis in **E**arly **C**D4 is **A**lbicans.