Candidiasis

Introduction & Etiology - The Yeast Beast

• Causative Organisms:
  • Candida albicans (most common).
  • Non-albicans: C. glabrata, C. tropicalis, C. parapsilosis.
  • C. krusei (fluconazole-resistant).
• Nature: Commensal; opportunistic pathogen.
• Virulence: Adherence, dimorphism (yeast→hyphae for invasion), biofilms, enzymes.
• Predisposing Factors: Diabetes, immunosuppression (HIV, steroids), antibiotics, pregnancy, OCPs, obesity, occlusion, maceration, age extremes, catheters, IV drug use.
• 📌 Mnemonic (CANDIDIASIS): Corticosteroids, Antibiotics, Nutrition-poor, Diabetes, Immunosuppression, Age extremes, Skin breakdown, IV lines/devices, Systemic illness.

⭐ Candida albicans is a dimorphic fungus, existing as yeast and hyphal forms; the hyphal form is typically associated with tissue invasion.

Clinical Spectrum - Candida's Canvas

• Mucocutaneous Candidiasis:
  • Oral (Thrush): Pseudomembranous (white, scrapes off), Erythematous (red), Angular cheilitis, Median rhomboid glossitis.
  • Vulvovaginal (VVC): Itching, burning, 'cottage cheese' discharge. Recurrent VVC: ≥4 episodes/year.
  • Balanitis: Penile erythema, papules, pustules.
• Cutaneous Candidiasis:
  • Intertrigo: Red, moist plaques in skin folds (axillae, groin). Satellite papules/pustules are key.
  • Diaper Dermatitis: Beefy red plaques, satellite lesions.
  • Paronychia & Onychomycosis: Nail fold inflammation, nail changes.
• Chronic Mucocutaneous Candidiasis (CMC):
  • Persistent infections (skin, nails, mucous membranes).
  • Associated with endocrinopathies (APECED) or immune defects (IL-17 pathway).

⭐ Satellite lesions (papules/pustules beyond the main erythematous area) are a hallmark of cutaneous candidiasis, especially intertrigo.

Diagnostic Clues - Spotting Spores

• Clinical presentation often suggestive.
• Microscopy:
  • KOH Mount (10-20%): Skin/nail/discharge. Shows budding yeast cells & pseudohyphae.
  • Gram Stain: Gram-positive budding yeasts & pseudohyphae.
• Culture (not routine for uncomplicated cases; useful for recurrent/resistant infections or species ID):
  • Sabouraud Dextrose Agar (SDA): Creamy, opaque colonies.
  • CHROMagar Candida: Differential growth/color for species identification (e.g., C. albicans - green, C. tropicalis - blue).
• Germ Tube Test: C. albicans forms germ tubes in serum at 37°C (2-3 hrs) - presumptive identification.
• Wood's Lamp: Negative.
• Biopsy (rarely needed): May show yeasts & pseudohyphae in stratum corneum.

⭐ On KOH mount, Candida typically shows budding yeast cells and pseudohyphae, which are chains of budding yeast cells that have failed to detach.

Treatment Toolkit - Fungal Fight Plan

• General Measures: Keep areas dry, weight ↓, glycemic control (diabetics), avoid occlusive clothing.
• Topical Antifungals (Localized):
  • Polyenes: Nystatin (cream, powder; oral suspension for thrush - swish & swallow/spit).
  • Azoles: Clotrimazole, Miconazole, Ketoconazole, Econazole, Sertaconazole.
  • Ciclopirox olamine.
  • Duration: 1-4 weeks; continue 1 week post-resolution.
• Systemic Antifungals (Extensive/Recurrent/Nail/Immunocompromised):
  • Azoles: Fluconazole (DOC; VVC: 150 mg single dose; Oropharyngeal: 100-200 mg/day for 7-14 days), Itraconazole.
  • Echinocandins (IV, severe/invasive): Caspofungin, Micafungin.
• 📌 Mnemonic (Fluconazole resistant): "Krusei and Glabrata Hate Fluconazole" (C. krusei, C. glabrata).

⭐ Fluconazole 150 mg single oral dose is a highly effective and convenient treatment for uncomplicated vulvovaginal candidiasis.

High‑Yield Points - ⚡ Biggest Takeaways

• Causative Agent: Candida albicans (commonest), a dimorphic fungus.
• Hallmark Lesion: Beefy red plaques with satellite lesions (papules/pustules) in intertriginous areas.
• Oral Thrush: White, curd-like plaques on mucosa, easily scraped off, leaving red base.
• Vulvovaginal: Thick, "cottage cheese" discharge; intense pruritus and erythema.
• Diagnosis: KOH mount shows pseudohyphae and budding yeast cells.
• Risk Factors: Diabetes, immunosuppression (HIV, steroids), antibiotics, pregnancy, obesity.
• Treatment: Topical azoles (e.g., clotrimazole) or nystatin; oral fluconazole for severe/recurrent cases.