Candida parapsilosis is a yeast species that has emerged as the second or third most common cause of candidemia, particularly in neonatal intensive care units, surgical patients, and recipients of parenteral nutrition or central venous catheters. Unlike C. albicans, it commonly forms biofilms on prosthetic devices and catheters and shows intrinsic reduced susceptibility to echinocandins (caspofungin, micafungin, anidulafungin) due to a polymorphism (P660A) in the FKS1 gene that elevates minimum inhibitory concentrations 5-10 fold above other species. Recent global outbreaks have highlighted clonal spread of fluconazole-resistant strains harboring ERG11 mutations (Y132F most common), with cross-resistance among triazoles and limited treatment options.
Risk factors include prematurity (especially very low birth weight infants), prolonged hospitalization, central venous catheters, total parenteral nutrition, broad-spectrum antibiotics, abdominal surgery, immunosuppression, and stays in units with previously documented outbreaks. Clinical presentation is similar to other candidemias: fever unresponsive to antibacterials, sepsis, endophthalmitis, endocarditis (especially with prosthetic valves), and rare deep tissue infection. Diagnosis relies on positive blood cultures (typically within 1-3 days), with subsequent species identification by MALDI-TOF and antifungal susceptibility testing essential for guiding therapy. Catheter-related infections often resolve only with line removal.
Treatment depends on local epidemiology and susceptibility patterns. In susceptible isolates, fluconazole 800 mg loading then 400-800 mg daily for at least 14 days after first negative blood culture is appropriate; some experts prefer this over echinocandins for proven C. parapsilosis. Echinocandins remain effective in many strains despite elevated MICs but should be reassessed if clinical response is suboptimal. Resistant strains require liposomal amphotericin B 3-5 mg/kg/day or voriconazole based on susceptibility. Source control through catheter removal is essential. Prophylaxis with fluconazole in high-risk neonatal units, strict catheter care bundles, and antimicrobial stewardship are key for prevention. Outbreaks require enhanced infection control, environmental sampling, and molecular typing to identify clonal spread.