β-D-Glucan Testing in Candidemia: Determinants of Positivity and Association With Mortality.

Background: Serum 1,3-β-d-glucan (BDG) tests are frequently used for diagnosing invasive candidiasis. However, BDG tests remain negative in many patients with candidemia, and factors influencing the probability for positive test results are poorly understood.

Objectives: To study clinical and microbiological factors predictive of a positive BDG test, as well as the association of a positive BDG test with mortality in patients with candidemia.

Methods: In a retrospective cohort of patients with candidemia, BDG was analysed by the Glucatell assay and the Wako Beta-Glucan Test. Predisposing conditions, focus of infection and other variables were retrieved from medical charts and laboratory databases. Their association with a positive BDG test, and the association between positive BDG and death was tested in univariate analysis and multivariable logistic regression.

Results: We included 134 patients with candidemia. Positive BDG and a non-abdominal deep-seated focus of infection (e.g., hematogenously disseminated infection and deep mediastinal/pleural candidiasis) were positively correlated in univariate and multivariable analyses [Wako adjusted odds ratio 9.11 (95% CI 1.66-172, p = 0.039), Glucatell adjOR 9.14 (95% CI 1.66-172, p = 0.039)]. Having a positive BDG test increased the risk for 90 days mortality after controlling for potential confounders, mainly age, septic shock, and ICU admission [Wako adjOR 4.73 (95% CI 1.71-14.7, p = 0.0043), Glucatell adjOR 3.59 (95% CI 1.33-10.6, p = 0.015)].

Conclusions: In patients with candidemia, a positive BDG test is more common in the presence of a concomitant non-abdominal deep-seated infection. Patients with a positive BDG test have a higher 90-day mortality.