Wako β‐D‐glucan assay can be used to measure serum β‐D‐glucan in Sudanese patients to aid with diagnosis of eumycetoma caused by Madurella mycetomatis

Abstract

Mycetoma is a chronic subcutaneous neglected tropical disease (NTD), recognized by WHO as a skin NTD in 2016. It is characterized by the formation of tumorous lesions and the presence of multiple sinuses from which grains are secreted. Mycetoma is caused by bacteria (actinomycetoma) or fungi (eumycetoma), 1 which are found embedded in the grains. 2 The colour and substance of the grain are dependent on the etiologic agent. 1 Within the fungal hyphae inside the grain, cell wall components such as chitin and beta-glucan are found. 2 In bacterial grains, L-and meso-isomers of diaminopimelic acid can be found. 3 To ensure proper patient management, discrimination of the two types is needed. 4 Currently, the gold standard diagnosis relies on histology and culture. 5 However, this has low diagnostic accuracy, is time-consuming and invasive as a deep surgical biopsy is needed. Molecular assays have been developed to solve some of these issues, 5 however,

Using (1,3)‐β‐D‐glucan concentrations in serum to monitor the response of azole therapy in patients with eumycetoma caused by Madurella mycetomatis

“…In this study, we evaluated whether serum (1,3)‐β‐D‐glucan concentrations could be used to monitor treatment response in patients with eumycetoma. Before the start of therapy, a (1,3)‐β‐D‐glucan concentration above the WAKO recommended cut‐off value of 7 pg/mL was noted in 62% of the patients, and in 73% of the patients, the (1,3)‐β‐D‐glucan concentration was above the 5.5 pg/mL cut‐off value we previously proposed for mycetoma patients 10 . In 28 patients, no detectable (1,3)‐β‐D‐glucan levels were found at visit 0.…”

“…Before the start of therapy, a (1,3)-β-D-glucan concentration above the WAKO recommended cut-off value of 7 pg/mL was noted in 62% of the patients, and in 73% of the patients, the (1,3)-β-D-glucan concentration was above the 5.5 pg/ mL cut-off value we previously proposed for mycetoma patients. 10 In 28 patients, no detectable (1,3)-β-D-glucan levels were found at visit 0. Although disappointing, these findings are in line with previous studies performed in other fungal infections.…”

“…Serum (1,3)-β-D-glucan concentrations were measured using the WAKO (1,3)-β-D-glucan assay as previously described. 10 Briefly, following thawing and mixing, 100 μL of serum was added to 900 μL of pretreatment solution and incubated for 10 min at 70°C in a Thermostation TS-70/16 (WAKO). After incubation, the sample was transferred to an ice box for 3 min.…”

“…(1–3)‐β‐D‐glucan is a fungal cell wall component that is used as a broad‐based marker for invasive fungal infections 8,9 . Fungal (1,3)‐β‐D‐glucan has been detected in the serum of patients with eumycetoma 10,11 and a correlation has been observed between higher (1,3)‐β‐D‐glucan concentrations and larger lesions. Furthermore, in other fungal infections, (1,3)‐β‐D‐glucan concentrations have been shown to decline during therapy 12,13 .…”

Diagnostics to support mycetoma management—Development of two target product profiles

“…More work is needed to either transfer this technique to a point‐of‐care technique that can be used in local villages by individuals with minimal training or to develop a new point‐of‐care tool to differentiate actinomycetoma from eumycetoma. Serological markers, such as β‐1,3‐ D ‐glucan, currently in use for other fungal infections are not specific enough, as certain actinomycetes can cause false positives with these assays [ 22 ]. This challenge might be solved by identifying alternative serological markers, developing lateral flow assays, ELISAs, or spot assays or DNA markers.…”