Role of (1-3)-Β-D-Glucan Test in the Diagnosis of Invasive Fungal Infections among High-Risk Patients in a Tertiary Care Hospital

Abstract

Background Invasive fungal infections (IFI) are associated with high mortality. Serum fungal biomarkers offer an advantage over the traditional methods in early diagnosis and better clinical outcomes. The aim of the study was to evaluate the role of (1-3)-β-D-glucan (BDG) assay in the patients suspected of IFI. Materials and Methods This prospective study was conducted in the Department of Microbiology, Dayanand Medical College and Hospital, Ludhiana, over a period of 1 year. A total of 862 serum samples were received from patients suspected of IFI, for the BDG test (Fungitell, Associates of Cape Cod Inc., USA). The test was performed as per kit protocol. Appropriate samples were processed for KOH fungal smear and fungal culture. Blood culture was done by Bactec (Biomerieux). Statistical Analysis Results were analyzed using descriptive statistical methods. Sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV) were calculated at different cutoffs. In addition, the receiver operating characteristic (ROC) curve using SPSS 21.00 software was calculated and the diagnostic accuracy was shown by the area under the ROC curve (AUC). Results Among 862 patients, 546 (63.3%) were males. The predominant age group (25.6%) was between 61 and 70 years. The most common risk factor (54.8%) was prolonged intensive care unit stay. Out of the total samples, 455 (52.8%) samples were found positive for BDG. Fungal elements were seen in 48 (10.5%) KOH smears and fungal growth was obtained in 81 (17.8%) cultures. Comparison of BDG assay and culture at different cutoffs yielded AUC-0.823. Sensitivity (100%), specificity (51.3%), accuracy (55.6%), PPV (15.8%), and NPV (100%) were observed at the kit cutoff of 80 pg/mL. Optimum sensitivity and specificity of 79.2% and 70.3%, respectively, were observed at a cutoff of 142.4pg/mL. A significant correlation was observed between BDG positivity and piperacillin-tazobactam use and dialysis. Among BDG positive patients, 38(8.4%) succumbed to death. Conclusion Detection of BDG helps in the early diagnosis of IFI in critically ill patients. As the assay has a high NPV, a negative test can be used to stop the empirical antifungal drugs. The use of a higher cutoff can be useful to avoid false-positive results.

Keywords: (1–3)-β-D-glucan; fungal culture; invasive fungal infections.

Fig. 1

Area wise distribution of (1–3)-β-D-glucan assay positivity ( n  = 862). ICU, intensive care unit.

Fig. 2

Receiver operating characteristic (ROC) curve.