Invasive Candidiasis

Invasive candidiasis is a serious systemic fungal infection caused by Candida species, affecting the bloodstream (candidemia) or deep-seated organs. It primarily occurs in immunocompromised patients, critically ill individuals, or those with indwelling medical devices.

Definition

Epidemiology

Incidence higher in hospitalized and ICU patients, especially with central venous catheters
Most common species: Candida albicans, followed by C. glabrata, C. parapsilosis, C. tropicalis, C. krusei
Risk factors: immunosuppression, neutropenia, broad-spectrum antibiotic use, total parenteral nutrition, recent surgery
Mortality: 20–40% despite appropriate therapy, higher in delayed diagnosis
Affects all age groups, including neonates (especially preterm) and adults

Etiology

Candida species (opportunistic yeasts) invading bloodstream or sterile tissues
Predisposing conditions: neutropenia, organ transplantation, chemotherapy, HIV/AIDS
Invasive devices: central venous catheters, urinary catheters
Disruption of normal microbiota by antibiotics or mucosal barrier injury facilitates invasion
Nosocomial outbreaks possible, particularly in ICUs

Pathophysiology

Candida adheres to epithelial surfaces and medical devices, forming biofilms
Invasion of bloodstream or deep tissues triggers systemic inflammatory response
Neutrophils and monocytes attempt fungal clearance; impaired immunity increases dissemination
End-organ seeding can occur in kidneys, liver, spleen, eyes, heart, CNS
Cytokine storm and vascular invasion contribute to sepsis and multi-organ dysfunction
Biofilm formation on catheters complicates eradication and treatment