A 52-year-old woman with poorly controlled diabetes mellitus type 2 presents with recurrent vulvovaginal candidiasis. Culture grows Candida albicans. Which feature distinguishes this presentation from Candida glabrata vulvovaginitis?

## C. albicans vs. C. glabrata Vulvovaginitis ### Clinical Context **Key Point:** The question asks which feature **distinguishes C. albicans** vulvovaginitis from C. glabrata. The presence of pseudohyphae and germ tubes on wet mount microscopy is the hallmark morphological feature of *C. albicans* that is **absent** in *C. glabrata*, making Option D the correct distinguishing feature. ### Comparison Table | Feature | C. albicans | C. glabrata | | --- | --- | --- | | **Prevalence in vulvovaginitis** | 85–90% of cases | 5–15% of cases | | **Germ tubes & pseudohyphae** | **Present (positive)** | Absent (small yeast cells only) | | **Azole susceptibility** | Usually susceptible to fluconazole | Reduced susceptibility; some resistance | | **Echinocandin susceptibility** | Susceptible | Susceptible (often preferred for resistant strains) | | **Predisposing factors** | Diabetes, antibiotics, immunosuppression | Diabetes, prior azole use, immunosuppression | | **Clinical presentation** | Acute vulvar erythema, curd-like discharge | Similar acute presentation | | **Wet mount finding** | Pseudohyphae + budding yeast + germ tubes | Small budding yeast only (no pseudohyphae) | ### Why Pseudohyphae and Germ Tubes Are the Distinguishing Feature **High-Yield:** *C. albicans* is uniquely identified by its ability to form **germ tubes** (Reynolds-Braude phenomenon) when incubated in serum at 37°C for 2–3 hours, and **pseudohyphae** visible on wet mount microscopy. *C. glabrata* produces only small, oval budding yeast cells and **never forms pseudohyphae or germ tubes** — this is a fundamental morphological distinction used in clinical microbiology laboratories. **Clinical Pearl:** The germ tube test is a rapid, inexpensive bedside/laboratory test that positively identifies *C. albicans* (and *C. dubliniensis*) with ~95% specificity. A positive germ tube test = *C. albicans*; a negative test = non-albicans Candida (including *C. glabrata*). ### Why the Other Options Are Incorrect - **Option A (Elevated blood glucose):** Both *C. albicans* and *C. glabrata* are associated with poorly controlled diabetes mellitus. This is NOT a distinguishing feature. - **Option B (Acute vulvar erythema and pruritus):** Both species cause similar acute clinical presentations. This does NOT distinguish them. - **Option C (Fluconazole resistance and echinocandin requirement):** This is actually a feature of *C. glabrata*, NOT *C. albicans*. *C. albicans* is typically fluconazole-susceptible. Stating this as a feature of *C. albicans* presentation would be factually incorrect. **Mnemonic:** **ALBICANS = Always forms germ tubes, Looks like pseudohyphae, Budding yeast + hyphae, Identified by germ tube test, Candida most common, Azole-susceptible, No resistance typically, Serum germ tube positive** — captures the morphological essence. [cite: Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, 9th ed.; Murray PR, Medical Microbiology, 8th ed.; Sobel JD, Vulvovaginal candidiasis, Lancet 2007]