A screening of the MMV Pathogen Box® reveals new potential antifungal drugs against the etiologic agents of chromoblastomycosis.

Chromoblastomycosis (CBM) is a chronic subcutaneous mycosis caused by traumatic implantation of many species of black fungi. Due to the refractoriness of some cases and common recurrence of CBM, a more effective and less time-consuming treatment is mandatory. The aim of this study was to identify compounds with in vitro antifungal activity in the Pathogen Box® compound collection against different CBM agents. Synergism of these compounds with drugs currently used to treat CBM was also assessed. An initial screening of the drugs present in this collection at 1 µM was performed with a Fonsecaea pedrosoi clinical strain according to the EUCAST protocol. The compounds with activity against this fungus were also tested against other seven etiologic agents of CBM (Cladophialophora carrionii, Phialophora verrucosa, Exophiala jeanselmei, Exophiala dermatitidis, Fonsecaea monophora, Fonsecaea nubica, and Rhinocladiella similis) at concentrations ranging from 0.039 to 10 µM. The analysis of potential synergism of these compounds with itraconazole and terbinafine was performed by the checkerboard method. Eight compounds inhibited more than 60% of the F. pedrosoi growth: difenoconazole, bitertanol, iodoquinol, azoxystrobin, MMV688179, MMV021013, trifloxystrobin, and auranofin. Iodoquinol produced the lowest MIC values (1.25-2.5 µM) and MMV688179 showed MICs that were higher than all compounds tested (5 - >10 µM). When auranofin and itraconazole were tested in combination, a synergistic interaction (FICI = 0.37) was observed against the C. carrionii isolate. Toxicity analysis revealed that MMV021013 showed high selectivity indices (SI ≥ 10) against the fungi tested. In summary, auranofin, iodoquinol, and MMV021013 were identified as promising compounds to be tested in CBM models of infection.

Species diversity, antifungal susceptibility and phenotypic and genotypic characterisation of Exophiala spp. infecting patients in different medical centres in Brazil.

The Exophiala genus is responsible for many superficial and invasive infections resulting from black fungi. Identification of Exophiala at the species level is based on morphological observations complemented by molecular tests. The aim of this study was to identify 23 clinical isolates of Exophiala spp. and evaluate the antifungal susceptibility to seven different agents. Molecular identification was based on an analysis of ITS region of rDNA using genomic databases. The micromorphology was evaluated by microculture and scanning electron microscopy. The susceptibility tests were performed using the antifungal agents 5-fluorocytosine (5-FC), amphotericin B (AMB), itraconazole (ITC), voriconazole (VRC), posaconazole (PSC), caspofungin (CFG) and terbinafine (TRB). The ITS analysis identified 100% of the following isolates as: E. dermatitidis (8), E. xenobiotica (6), E. bergeri (4), E. oligosperma (3), E. spinifera (1) and E. mesophila (1). The antifungal susceptibility tests showed that the triazoles compounds were in vitro the most active agents against Exophiala. ITS sequencing enabled the accurate identification of the 23 tested isolates. The triazoles, particularly itraconazole and posaconazole, exhibited MIC values lower than AMB, CAS and 5-FC. Although the guidelines do not indicate AMB for treatment against Exophiala spp., this study showed activity for all of the tested species, except E. mesophila.

Melanized fungal infections in kidney transplant recipients: contributions to optimize clinical management.

OBJECTIVES: This is a retrospective and observational study addressing clinical and therapeutic aspects of melanized fungal infections in kidney transplant recipients. METHODS: We retrospectively reviewed medical records of all patients admitted between January 1996 and December 2013 in a single institution who developed infections by melanized fungi. RESULTS: We reported on 56 patients aged between 30 and 74 years with phaeohyphomycosis or chromoblastomycosis (0.54 cases per 100 kidney transplants). The median time to diagnosis post-transplant was 31.2 months. Thirty-four (60.8%) infections were reported in deceased donor recipients. Fifty-one cases of phaeohyphomycosis were restricted to subcutaneous tissues, followed by two cases with pneumonia and one with brain involvement. Most dermatological lesions were represented by cysts (23/51; 45.1%) or nodules (9/51; 17.9%). Exophiala spp. (34.2%) followed by Alternaria spp. (7.9%) were the most frequent pathogens. Graft loss and death occurred in two patients and one patient, respectively. Regarding episodes of subcutaneous phaeohyphomycosis, a complete surgical excision without antifungal therapy was possible in 21 of 51 (41.2%) patients. Long periods of itraconazole were required to treat the other 30 (58.8%) episodes of subcutaneous disease. All four cases of chromoblastomycosis were treated only with antifungal therapy. CONCLUSIONS: Melanized fungal infections should be considered in the differential diagnosis of all chronic skin lesions in transplant recipients. It is suggested that the impact of these infections on graft function and mortality is low. The reduction in immunosuppression should be limited to severely ill patients.

In vitro susceptibility of environmental isolates of Exophiala dermatitidis to five antifungal drugs.

Several dematiaceous fungi frequently isolated from nature are involved in cases of superficial lesions to lethal cerebral infections. Antifungal susceptibility data on environmental and clinical isolates are still sparse despite the advances in testing methods. The objective of this study was to examine the activities of 5-flucytosine, amphotericin B, itraconazole, voriconazole and terbinafine against environmental isolates of Exophiala strains by minimum inhibition concentration (MIC) determination. The strains were obtained from hydrocarbon-contaminated soil, ant cuticle and fungal pellets from the infrabuccal pocket of attine gynes. Broth microdilution assay using M38-A2 reference methodology for the five antifungal drugs and DNA sequencing for fungal identification were applied. Terbinafine was the most active drug against the tested strains. It was observed that amphotericin B was less effective, notably against Exophiala spinifera, also studied. High MICs of 5-flucytosine against Exophiala dermatitidis occurred. This finding highlights the relevance of studies on the antifungal resistance of these potential opportunistic species. Our results also contribute to a future improvement of the standard methods to access the drug efficacy currently applied to black fungi.

Phytochemistry and antifungal properties of the newly discovered tree Pleodendron costaricense.

Gas chromatography analysis of the essential oils of leaves and bark collected from the newly discovered tree Pleodendron costaricense identified alpha-pinene, beta-pinene, beta-myrcene, beta-thujene, and beta-caryophyllene as their major constituents. Phytochemical analysis of P. costaricense parts led to the isolation and identification of delta-tocotrienol, beta-sitosterol, four known drimane-type sesquiterpenes, cinnamodial (1), cinnamosmolide (2), polygodial (3), and mukaadial (4), and two new compounds, a drimane-type sesquiterpene, parritadial (5), and an eremophilane-type sesquiterpene, pleodendione (6). Antifungal assays with the two major compounds, 1 and 2, were carried out, and results showed a high activity of 1 against Alternaria alternata (MIC = 3.9 microg/mL), Candida albicans azole-resistant strain D10, and Wangiella dermatitides (MICs = 15.6 microg/mL). Compound 2 showed less potent antifungal activities than 1 but was more effective against Candida albicans azole-resistant strain CN1A (MIC = 23.4 microg/mL) and Pseudallescheria boydii (MIC = 78.1 microg/mL). A combination of the dialdehyde sesquiterpenes with dillapiol showed a synergistic antifungal effect with 1 and an additive effect with 4 and 5.