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Introduction: (1,3)-β-D-glucan is a panfungal biomarker secreted by many fungi, including Madurella mycetomatis, the main causative agent of eumycetoma. Previously we demonstrated that (1,3)-β-D-glucan was present in serum of patients with eumycetoma. However, the use of (1,3)-β-D-glucan to monitor treatment responses in patients with eumycetoma has not been evaluated. Materials and Methods: In this study, we measured (1,3)-β-D-glucan concentrations in serum with the WAKO (1,3)-β-D-glucan assay in 104 patients with eumycetoma treated with either 400 mg itraconazole daily, or 200 mg or 300 mg fosravuconazole weekly. Serial serum (1,3)-β-D-glucan concentrations were measured at seven different timepoints. Any correlation between initial and final (1,3)-β-D-glucan concentrations and clinical outcome was evaluated. Results: The concentration of (1,3)-β-D-glucan was obtained in a total of 654 serum samples. Before treatment, the average (1,3)-β-D-glucan concentration was 22.86 pg/mL. During the first 6 months of treatment, this concentration remained stable. (1,3)-β-D-glucan concentrations significantly dropped after surgery to 8.56 pg/mL. After treatment was stopped, there was clinical evidence of recurrence in 18 patients. Seven of these 18 patients had a (1,3)-β-D-glucan concentration above the 5.5 pg/mL cut-off value for positivity, while in the remaining 11 patients, (1,3)-β-D-glucan concentrations were below the cut-off value. This resulted in a sensitivity of 38.9% and specificity of 75.0%. A correlation between lesion size and (1,3)-β-D-glucan concentration was noted. Conclusion: Although in general (1,3)-β-D-glucan concentrations can be measured in the serum of patients with eumycetoma during treatment, a sharp decrease in β-glucan concentration was only noted after surgery and not during or after antimicrobial treatment. (1,3)-β-D-glucan concentrations were not predictive for recurrence and seem to have no value in determining treatment response to azoles in patients with eumycetoma. [ABSTRACT FROM AUTHOR]

Background: Eumycetoma is a neglected tropical disease. It is a chronic inflammatory subcutaneous infection characterised by painless swellings which produce grains. It is currently treated with a combination of itraconazole and surgery. In an ongoing clinical study, the efficacy of fosravuconazole, the prodrug of ravuconazole, is being investigated. For both itraconazole and ravuconazole, no clinical breakpoints or epidemiological cut‐off values (ECV) to guide treatment are currently available. Objective: To determine tentative ECVs for itraconazole and ravuconazole in Madurella mycetomatis, the main causative agent of eumycetoma. Materials and Methods: Minimal inhibitory concentrations (MICs) for itraconazole and ravuconazole were determined in 131 genetically diverse clinical M. mycetomatis isolates with the modified CLSI M38 broth microdilution method. The MIC distributions were established and used to determine ECVs with the ECOFFinder software. CYP51A sequences were sequenced to determine whether mutations occurred in this azole target gene, and comparisons were made between the different CYP51A variants and the MIC distributions. Results: The MICs ranged from 0.008 to 1 mg/L for itraconazole and from 0.002 to 0.125 mg/L for ravuconazole. The M. mycetomatis ECV for itraconazole was 1 mg/L and for ravuconazole 0.064 mg/L. In the wild‐type population, two CYP51A variants were found for M. mycetomatis, which differed in one amino acid at position 499 (S499G). The MIC distributions for itraconazole and ravuconazole were similar between the two variants. No mutations linked to decreased susceptibility were found. Conclusion: The proposed M. mycetomatis ECV for itraconazole is 1 mg/L and for ravuconazole 0.064 mg/L. [ABSTRACT FROM AUTHOR]