A 38-year-old woman with poorly controlled diabetes mellitus presents with vaginal itching and thick white discharge. Vaginal culture confirms Candida albicans. Which is the most common causative organism of candidiasis in immunocompetent individuals?

Explanation

## Epidemiology of Candida Species **Key Point:** Candida albicans accounts for 50–90% of all candidiasis cases worldwide, making it the most common causative organism across all patient populations. ### Frequency Distribution | Organism | Prevalence | Clinical Context | |----------|-----------|------------------| | C. albicans | 50–90% | Immunocompetent, immunocompromised | | C. glabrata | 10–30% | Elderly, post-azole exposure | | C. auris | <5% (emerging) | Healthcare-associated, MDR | | C. tropicalis | <5% | Immunocompromised, invasive disease | **High-Yield:** C. albicans is a dimorphic fungus capable of forming hyphae and pseudohyphae, which enhances tissue invasion and virulence. This morphological plasticity is a key reason for its predominance in candidiasis. ### Clinical Pearl In this case, the patient's poorly controlled diabetes is a risk factor for candidiasis, but C. albicans remains the most common cause regardless of glycemic control. The thick white discharge and vaginal culture confirmation are classic for vulvovaginal candidiasis (VVC), where C. albicans causes >80% of cases. ### Mnemonic **CAST** — Common Antifungal Susceptibility Trends: - **C** — Candida albicans (most common, susceptible to azoles) - **A** — Auris (emerging, multidrug-resistant) - **S** — Species shift (glabrata after azole exposure) - **T** — Tropicalis (invasive, immunocompromised hosts) [cite:KD Tripathi 8e Ch 47]