Bloodstream Invasion Dominates Mortality in Invasive Candidiasis: Single-center Insights on Abdominal Origins, Antifungal Efficacy, and Biomarker-Driven Prognosis

Background Invasive candidiasis (IC), particularly candidemia (56.7% mortality), faces diagnostic delays with blood cultures. Early identification of infection sources and biomarkers (PCT, IL-6, β-D-glucan) could enable prompt intervention. Methods A 12-month retrospective cohort study analyzed 223 hospitalized IC patients (2013–2024; incidence 31.9/100,000 patient-years) confirmed by sterile-site mycological evidence. Biomarkers, microbiology (BD/Vitek, CLSI susceptibility), and mortality predictors were assessed using regression and Kaplan-Meier analysis (SPSS). Results Patients were predominantly male (1.45:1), median age 60.1 years. Blood culture was the primary diagnostic specimen (33.5%); 35.2% were polymicrobial. Among 88 blood culture-positive cases, 77.3% detected solely in aerobic bottles (mean TTP 39.1h). C. albicans predominated (52.6% of isolates); resistance: fluconazole 5.8%, itraconazole 11.0%, voriconazole 7.0%. Primary infection sources: abdominal (46.6%), catheter (18.8%). Overall mortality was 46.2%, varying by focus: bloodstream infection (BSI: 70.3%), abdominal (43.2%), catheter (26.1%); joint infections: 0%. In single-species infections (n = 140), PCT demonstrated highest diagnostic value (AUC 0.827; sensitivity 0.667, specificity 0.862 at 0.778 µg/mL). Fluconazole conferred superior 90-day survival vs. caspofungin (0.815 vs 0.330; p < 0.001). Regression identified significant mortality predictors: PCT ≥ 0.778 ng/mL (OR 3.800, 95% CI 1.995–7.237, p < 0.001), IL-6 ≥ 25.375 pg/mL (OR 3.667, 95% CI 1.372–9.795, p = 0.01), BSIs (OR 4.431, 95% CI 2.438–8.054, p < 0.001), ICU admission (OR 2.351, 95% CI 1.269–4.356, p = 0.007); Fluconazole was protective (OR 0.102, 95% CI 0.033–0.316). Conclusion IC mortality (46.2%) was highest in BSIs (70.3%). Elevated PCT, IL-6, and BSI are significant predictors. Fluconazole is protective. C. albicans (52.6%) and abdominal infections (46.6%) predominated.