Contribution of Candida biomarkers and DNA detection for the diagnosis of invasive candidiasis in ICU patients with severe abdominal conditions

BACKGROUND To assess the performance of Candida albicans germ tube antibody (CAGTA), (1 → 3)-ß-D-glucan (BDG), mannan antigen (mannan-Ag), anti-mannan antibodies (mannan-Ab), and Candida DNA for diagnosing invasive candidiasis (IC) in ICU patients with severe abdominal conditions (SAC). METHODS A prospective study of 233 non-neutropenic patients with SAC on ICU admission and expected stay ≥ 7 days. CAGTA (cutoff positivity ≥ 1/160), BDG (≥80, 100 and 200 pg/mL), mannan-Ag (≥60 pg/mL), mannan-Ab (≥10 UA/mL) were measured twice a week, and Candida DNA only in patients treated with systemic antifungals. IC diagnosis required positivities of two biomarkers in a single sample or positivities of any biomarker in two consecutive samples. Patients were classified as neither colonized nor infected (n = 48), Candida spp. colonization (n = 154) (low-grade, n = 130; high-grade, n = 24), and IC (n = 31) (intra-abdominal candidiasis, n = 20; candidemia, n = 11). RESULTS The combination of CAGTA and BDG positivities in a single sample or at least one of the two biomarkers positive in two consecutive samples showed 90.3 % (95 % CI 74.2-98.0) sensitivity, 42.1 % (95 % CI 35.2-98.8) specificity, and 96.6 % (95 % CI 90.5-98.8) negative predictive value. BDG positivities in two consecutive samples had 76.7 % (95 % CI 57.7-90.1) sensitivity and 57.2 % (95 % CI 49.9-64.3) specificity. Mannan-Ag, mannan-Ab, and Candida DNA individually or combined showed a low discriminating capacity. CONCLUSIONS Positive Candida albicans germ tube antibody and (1 → 3)-ß-D-glucan in a single blood sample or (1 → 3)-ß-D-glucan positivity in two consecutive blood samples allowed discriminating invasive candidiasis from Candida spp. colonization in critically ill patients with severe abdominal conditions. These findings may be helpful to tailor empirical antifungal therapy in this patient population.