亀井 克彦

BACKGROUND: Azoles target Cyp51A and Cyp51B in Aspergillus fumigatus. Mutations in cyp51A are known as the primary mechanisms of azole resistance. However, not all of them cause azole resistance. Among them, mutations related to improved susceptibility have not been reported so far. We found that two isolates that carry frameshift or nonsense mutations in cyp51A are more susceptible to azoles, even to fluconazole (FLCZ) (IC50: frameshift, 32 μg/mL; nonsense, 32 μg/mL) compared to other azole-susceptible strains (IC50: > 256 μg/mL). OBJECTIVES: We investigated the contribution of these two mutations to azole sensitivity and their effect on Cyp51A functions. METHODS: We transformed an experimental strain, AfS35, by replacing cyp51AWT with each of the mutated cyp51A and measured its MICs to azoles. We also evaluated the functions of mutated Cyp51A after suppression of Cyp51B, based on the notion that Cyp51A and Cyp51B complement each other. RESULTS: Induction of mutated cyp51A in AfS35 led to higher susceptibility to FLCZ (IC50: frameshift, 32-64 μg/mL; nonsense, 32 μg/mL). Transformants carrying either of the mutated cyp51A could not survive when cyp51B was suppressed, indicating that these cyp51A mutations result in Cyp51A dysfunction. Furthermore, a cyp51A-deleted mutant strain also showed increased susceptibility to FLCZ (IC50: 32 μg/mL), similar to cyp51A dysfunctional strains, while a cyp51B-deleted mutant strain showed unchanged susceptibility (IC50: > 256 μg/mL) from AfS35. CONCLUSIONS: It was suggested that FLCZ can inhibit Cyp51B rather than Cyp51A and that this unequal inhibition leads to higher azole susceptibility of the two isolates harbouring Cyp51A dysfunction.

Abstract Allodiploid hybrid species,Aspergillus latus, belonging to sectionNidulantes, is a hybrid ofA. spinulosporusand unknown species closely related toA. quadrilineatusandA. subltus. This hybrid has often been misidentified as the species in sectionNidulantes, such asA. nidulans,A. spinulosporus,A. sublatus, or other cryptic species. A. latushas not been reported in Japan as well as Asia so far. In this study, we screened 23 clinical strains identified asA. spinulosporusisolated in Japan from 2012 to 2023 and found sevenA. latusstrains. To characterize theA. latusstrains, we conducted comprehensive phenotyping including morphological observation, whole genome sequences and phylogenetic analysis based on calmodulin (CaM) gene. In addition, we conducted antifungal susceptibility testing forA. latusstrains. As a result, the morphological characters ofA. latuswere more similar to those ofA. spinulosporuscompared toA. sublatus. However, the ascospore ofA. latusdiffered from that ofA. spinulosporus.A. latusphylogenetically clustered withA. spinulosporusandA. sublatus. Furthermore,A. latusstrains showed reduced susceptibility to caspofungin and amphotericin B compared toA. spinulosporus, while they were susceptible to azoles. Our results suggest thatA. latushas been a causative pathogen of aspergillosis in Japan since 2013.

BACKGROUND: Gastrointestinal mucormycosis is a rapidly progressing and often fatal disease, predominantly affecting immunocompromised patients. Surgical intervention, in addition to antifungal therapy, is essential. Herein, we describe the successful management of appendiceal mucormycosis in a patient with acute promyelocytic leukemia through rapid surgical intervention and antifungal therapy. CASE PRESENTATION: A 29-year-old woman underwent autologous peripheral blood stem cell transplantation for acute promyelocytic leukemia (APL). Subsequently, her condition relapsed, and remission induction therapy was initiated. During the immunosuppressive period, she developed a fever and severe abdominal pain. Computed tomography revealed severe edema of the ileum, cecum, and ascending colon. Despite receiving multiple antibiotics, antivirals, and antifungals, her condition showed no improvement. Consequently, she underwent exploratory laparotomy, with no bowel perforation noted, revealing severe inflammation in the ileum, cecum, and ascending colon, as well as appendiceal necrosis. Appendectomy was performed, and histopathological analysis revealed hyphae in the vessels and layers of the appendiceal wall, suggestive of mucormycosis. The patient was diagnosed with appendiceal mucormycosis, and liposomal amphotericin B was administered. Subsequent monitoring showed no recurrence of mucormycosis. Genetic analysis of the resected tissue revealed Rhizopus microspores as the causative agent. CONCLUSIONS: Rapid surgical intervention and antifungal drug administration proved successful in managing appendiceal mucormycosis in a patient with APL. Early recognition and aggressive surgical intervention are imperative to improve outcomes in such patients.

Autosomal recessive CARD9 deficiency can underly deep and superficial fungal diseases. We identified two Japanese patients, suffering from superficial and invasive Candida albicans diseases, carrying biallelic variants of CARD9. Both patients, in addition to another Japanese and two Korean patients who were previously reported, carried the c.820dup CARD9 variant, either in the homozygous (two patients) or heterozygous (three patients) state. The other CARD9 alleles were c.104G > A, c.1534C > T and c.1558del. The c.820dup CARD9 variant has thus been reported, in the homozygous or heterozygous state, in patients originating from China, Japan, or South Korea. The Japanese, Korean, and Chinese patients share a 10 Kb haplotype encompassing the c.820dup CARD9 variant. This variant thus originates from a common ancestor, estimated to have lived less than 4,000 years ago. While phaeohyphomycosis caused by Phialophora spp. was common in the Chinese patients, none of the five patients in our study displayed Phialophora spp.-induced disease. This difference between Chinese and our patients probably results from environmental factors. (161/250).