Efficacy of the new β-D-glucan measurement kit for diagnosing invasive fungal infections, as compared with that of four conventional kits

Abstract

Background Each of the currently available (1→3)-β-D-glucan (BDG) measurement kits follows a different measurement method and cut-off value. Comparisons of diagnostic performance for invasive fungal infections (IFIs) are desirable. Additionally, ecological considerations are becoming increasingly important in the development of new measurement kits. Methods The plasma BDG levels in clinical samples were measured using the following currently available kits: the Fungitec G test MKII, the Fungitec G test ES, Fungitell, the β-Glucan test Wako, and the newly developed Wako kit (Wako-Eu). Wako-Eu uses a pre-treatment solution that conforms to European regulations for the registration, evaluation, authorisation, and restriction of chemicals. The values obtained for the samples using each kit were studied and compared. Results Of the 165 patients evaluated, 12 had IFIs, including pneumocystis pneumonia, aspergillosis, and candidiasis. BDG values obtained using the kits were moderately correlated with each other. Clinical diagnoses of the evaluated cases indicated that 21 false positives were diagnosed by at least one kit. The sensitivity of the Fungitell kit was relatively low, but those of the other four were over 90%. The specificity was above 90% for all kits. For positive predictive value, the Wako and the Wako-Eu methods were superior to the others owing to fewer false positive results. Conclusions The newly developed Wako-Eu method, which considers ecological concerns, shows diagnostic performance equivalent to that of its predecessor. To improve the diagnostic accuracy of IFIs, it is necessary to interpret the results carefully, giving due consideration to the characteristics of each measurement kit.