Background: β-D-glucan detection is a useful diagnostic indicator of invasive mycosis. However, the differences among the commercial β-D-glucan assays are unclear. Herein, we explored the diagnostic value of various β-D-glucan assay reagents.
Methods: This prospective observational study involved 175 eligible patients suspected to have fungal infections. For all participants, culture examinations were conducted with specimens obtained from the infected site (or blood culture), and β-D-glucan was measured using three commercial kits: Wako β-glucan test (Wako), Fungitech G-test MKII “Nissui” (MKII), and Fungitech G-test ES “Nissui” (ES).
Results: A total of 163 participants were included. Among them, 32 cases of invasive mycosis, 34 cases with mycotic colonization infection, and 97 cases with non-fungal infections were confirmed. Regarding the diagnostic value of the commercial kits for invasive mycosis, the areas under the receiver operating characteristic curves were > 0.8 for all the agents. However, on the basis of the cut-off value set by the manufacturer, the sensitivity and specificity of the three kits for definitive invasive infection were 80.0% and 90.6% with Wako, 80.0% and 80.7% with MKII, and 86.7% and 71.8% with ES, respectively. Moreover, the rate of false-positive β-D-glucan elevation detection in patients with negative fungal culture was 9.3% with Wako, 18.6% with MKII, and 23.7% with ES.
Conclusion: Despite the high diagnostic value of β-D-glucan detection in invasive fungal infections, caution should be exercised in interpreting the value of the assay reagents.

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The multidrug-resistant pathogen Candida auris is characterized by its aggregation under certain conditions, which affects its biofilm formation, drug susceptibility, and pathogenicity. Although the innate tendency to aggregate depends on the strain, the mechanism regulating C. auris aggregation remains unclear. We found that the culture supernatant from one of the 95 Actinomyces strains isolated from a deep-sea environment (IMAs2016D-66) inhibited C. auris aggregation. The cells grown in the presence of IMAs2016D-66 exhibited reduced hydrophobicity, biofilm formation, and enhanced proteolytic activity. In addition, the efflux pump activity of the fluconazole-resistant C. auris strain LSEM 3673 was stimulated by IMAs2016D-66, whereas no significant change was observed in the fluconazole-susceptible strain LSEM 0643. As the relationship between aggregative tendency and virulence in C. auris is still unclear, IMAs2016D-66 can serve as a tool for investigating regulatory mechanisms of phenotype switching and virulence expression of C. auris. Understanding of phenotype switching may help us not only to understand the pathogenicity of C. auris, but also to design new drugs that target the molecules regulating virulence factors.

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Control of infection caused by Microsporum canis in pet animals are important for prevention of zoonosis. Treatments for animal dermatophytosis have generally consisted of itraconazole (ITZ) and terbinafine (TRF); however, a TRF-resistant M. canis strain from a case of feline dermatophytosis has been reported. In the present study, we examined the in vitro susceptibility of clinical isolates of M. canis to new antifungal drugs, such as ravuconazole (RVZ) and luliconazole (LCZ). The results indicated that RVZ and LCZ are more effective than ITZ and TRF. Therefore, oral administration of RVZ or topical application of LCZ may serve as new treatment options.

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Multi-antifungal-resistant strains of Trichophyton indotineae and Trichophyton rubrum have been isolated in Japan. In the present study, we examined the in vitro susceptibility of terbinafine (TRBF) -resistant isolates of T. indotineae and T. rubrum to efinaconazole (EFCZ) and luliconazole (LUCZ). In all isolates, the minimum inhibitory concentrations were ≥ 32 mg/l for TRBF, < 0.03 to 16 mg/l for itraconazole, < 0.03 to 16 mg/l for ravuconazole, < 0.03 to 0.5 mg/l for LUCZ, and < 0.03 to 4 mg/l for EFCZ. Of note, T. rubrum NUBS21012 and T. indotineae NUBS 19006^T showed resistance to LUCZ and/or EFCZ unlike the other isolates.

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