Candidiasis

Definition

Candidiasis is a fungal infection caused by Candida species, commonly Candida albicans, affecting the skin, mucous membranes, and systemic organs in immunocompromised hosts.

Epidemiology

• Candida species are commensal organisms present in the oral cavity, gastrointestinal tract, and genitourinary tract
• Superficial infections are common worldwide in healthy individuals
• Invasive candidiasis occurs predominantly in immunocompromised patients (HIV, chemotherapy, transplant recipients)
• Females are at higher risk for vulvovaginal candidiasis
• Hospital-acquired candidemia is a major cause of morbidity in ICUs

Etiology

• Most commonly caused by Candida albicans; non-albicans species include C. glabrata, C. tropicalis, C. parapsilosis
• Risk factors: immunosuppression, prolonged antibiotic use, diabetes, neutropenia, indwelling catheters, broad-spectrum antibiotics, corticosteroid therapy
• Mucosal colonization precedes infection
• Disruption of normal microbiota or skin/mucosal barriers facilitates infection

Pathophysiology

• Candida adheres to epithelial surfaces and forms biofilms
• Morphological transition from yeast to hyphal form facilitates tissue invasion
• Host immune response (innate and adaptive) usually limits infection
• In immunocompromised hosts, Candida can invade bloodstream and organs
• Invasive disease leads to sepsis, organ dysfunction, and high mortality if untreated