FUNGUS · Yeast (dimorphic)
Candida albicans
Candida albicans — Gram stain (yeast + pseudohyphae)
Stain: Gram stain of cultureMorphology: Gram-positive budding yeast cells with pseudohyphae (and true germ tubes at 37°C)Yield: HIGHDifficulty: EASY
Image: Wikimedia Commons (CC BY-SA 4.0)
Key facts
**Pathogenesis**: Normal mucosal/skin flora that overgrows with antibiotic use, diabetes, T-cell dysfunction, or indwelling catheters. Transitions between yeast and pseudohyphal forms; germ tube formation at 37°C is diagnostic for C. albicans. **Diagnostic clue**: KOH wet mount or Gram stain shows budding yeast with pseudohyphae; germ tube test positive; cottage-cheese vaginal discharge or white plaques on tongue that scrape off (vs leukoplakia). **Virulence**: Hyphal invasion, biofilm formation on catheters.
Boards buzzwords
- pseudohyphae
- germ tube at 37°C
- thrush
- diaper rash
- vulvovaginitis
- esophagitis in HIV
Associated diseases
- Oral thrush (HIV, inhaled steroids, neonates)
- Esophagitis (AIDS-defining at CD4 <100)
- Vulvovaginal candidiasis
- Diaper dermatitis
- Catheter-related candidemia / endocarditis (IVDU)
- Chronic mucocutaneous candidiasis (T-cell defects)
Treatment
Mucocutaneous → topical nystatin, clotrimazole, or oral fluconazole; invasive candidemia → echinocandin (caspofungin, micafungin, anidulafungin) first-line; remove indwelling catheters
