Which Candida species is the most common cause of invasive candidiasis in hospitalized patients and is known for its ability to form biofilms on medical devices?

Explanation

## Candida albicans — The Most Common Pathogenic Species **Key Point:** Candida albicans is the leading cause of invasive candidiasis globally, accounting for approximately 50–60% of all candidemia cases in hospitalized patients. ### Why C. albicans Dominates **High-Yield:** C. albicans possesses several virulence factors that make it the most clinically significant: 1. **Dimorphism** — transitions between yeast and hyphal forms, enabling tissue invasion 2. **Biofilm formation** — adheres to central venous catheters, prosthetic valves, and other foreign bodies 3. **Adhesins** — surface proteins (e.g., Als1p, Hwp1) facilitate epithelial binding 4. **Secreted aspartic proteases (Saps)** — degrade host tissue and immune barriers ### Biofilm Characteristics **Clinical Pearl:** Candida albicans biofilms are: - Resistant to antifungal drugs (up to 1000-fold higher MICs than planktonic cells) - Difficult to eradicate without device removal - Common on indwelling catheters, prosthetic joints, and cardiac devices ### Comparison with Other Candida Species | Species | Biofilm | Invasiveness | Clinical Setting | Antifungal Resistance | |---------|---------|--------------|------------------|----------------------| | C. albicans | +++ (strong) | +++ (high) | Hospitalized, immunocompromised | Moderate (fluconazole-susceptible) | | C. auris | +++ (strong) | ++ (moderate) | Healthcare-associated outbreaks | HIGH (multidrug-resistant) | | C. glabrata | ++ (moderate) | ++ (moderate) | Older patients, azole exposure | HIGH (fluconazole-resistant) | | C. tropicalis | ++ (moderate) | ++ (moderate) | Immunocompromised, disseminated | Moderate | **Mnemonic:** **ACTS** — *Albicans, auris, tropicalis, glabrata* — the four most clinically relevant Candida species; **C. albicans** is **A**lways the most common. ### Why Other Options Are Incorrect - **C. auris** — Emerging multidrug-resistant pathogen, but less common overall; primarily healthcare-associated outbreaks - **C. glabrata** — Non-albicans Candida (NAC), increasing in prevalence but still less common than C. albicans - **C. tropicalis** — Associated with disseminated disease in immunocompromised hosts, but not the most common cause of invasive candidiasis [cite:Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases Ch 256]