Diversity of Fusarium species causing invasive and disseminated infections.

INTRODUCTION: Invasive fusariosis (IF) is considered an emerging fungal disease and an important problem worldwide that increasingly affects immunocompromised individuals. There is currently concern about establishing the genetic diversity and phylogenetic relationship of the species Fusarium causing invasive fusariosis. MATERIALS AND METHODS: The aim of this study was to characterize the molecular profile and morphological characteristics of Fusarium species isolated from 21 patients with invasive fusariosis. Multilocus sequence typing was performed for molecular identification of the following genes: the second largest subunit of the RNA polymerase gene (RPB2) and elongation factor 1 alpha (EF-1α). The morphological features of different species were carefully described and revised by experienced mycologists. RESULTS: Morphological and molecular analyses revealed that the F. solani species complex (FSSC) and F. oxysporum species complex (FOSC) were the most common species isolated from patients with invasive fusariosis; FSSC-2 h (5), FSSC-1 (2) and FOSC-183 (2) were the most frequent haplotypes. The macroscopic characterization revealed great variation in the tonalities of the FSSC colonies and particularities amongst the species in relation to the macroconidia structures, while the FOSC was more homogeneous and presented shades from white to lilac. CONCLUSIONS: Our study characterized the diversity, haplotypes, and morphological aspects of Fusarium species and the haplotypes prevalent in patients with invasive fusariosis. FSSC and FSSC-2 h were the predominant species and haplotype, respectively. Although we have described interesting morphological aspects in Fusarium species, particularly haplotypes, their identification cannot rely on phenotypical aspects. Molecular biology techniques are necessary and should be introduced for routine use in mycology laboratories.

In vitro pharmacokinetics/pharmacodynamics modeling and efficacy against systemic candidiasis in Drosophila melanogaster of a bisaryloxypropanamine derivative.

The number of deaths due to systemic fungal infections is increasing alarmingly, which is aggravated by the limitations of traditional treatments and multidrug resistance. Therefore, the research and development of new therapeutic options against pathogenic fungi is an urgent need. To evaluate the fungicidal activity of a synthetic compound, 1,3-bis-(3,4-dichlorophenoxy)propan-2-aminium chloride (2j), through time-kill studies and pharmacokinetics/pharmacodynamics (PK/PD) modeling. The protective effect of the compound was also evaluated using the Drosophila melanogaster minihost model of candidiasis. Mathematical modeling of time-kill data of compound 2j was performed to obtain PD characteristics. Additionally, Toll-deficient D. melanogaster flies were infected with a Candida albicans strain and treated with 2j. We observed that compound 2j demonstrated a time- and dose-dependent fungicidal effect against Candida spp. and dermatophytes, even at low concentrations, and rapidly achieved kill rates reaching the maximum effect in less than one hour. The efficacy of the compound against systemic candidiasis in D. melanogaster flies was comparable to that achieved by fluconazole. These results support the potential of compound 2j as a systemic antifungal agent candidate and serve as a starting point for further studies involving mammalian animal models.

Epidemiological aspects and characterization of the resistance profile of Fusarium spp. in patients with invasive fusariosis.

Introduction. The remarkable intrinsic resistance of Fusarium species to most antifungal agents results in high mortality rates in the immunocompromised population.Aims. This study aimed to investigate the epidemiology, clinical features and antifungal susceptibility of Fusarium isolates in patients with invasive fusariosis.Methodology. A total of 27 patients admitted to a referral hospital from January 2008 to June 2017 were evaluated. Antifungal susceptibility testing of isolates was performed by broth microdilution according to the Clinical and Laboratory Standards Institute guidelines.Results. Haematological malignancy was the predominant underlying condition, with an incidence of invasive fusariosis of 14.8 cases per 1000 patients with acute lymphoid leukaemia and 13.1 cases per 1000 patients with acute myeloid leukaemia. The Fusarium solani species complex (FSSC) was the most frequent agent group, followed by the Fusarium oxysporum species complex (FOSC). Voriconazole showed the best activity against Fusarium, followed by amphotericin B. Itraconazole showed high minimum inhibitory concentration values, indicating in vitro resistance. Clinical FSSC isolates were significantly (P<0.05) more resistant to amphotericin B and voriconazole than FOSC isolates.Conclusion. The present antifungal susceptibility profiles indicate a high incidence of fusariosis in patients with haematological malignancy. Species- and strain-specific differences in antifungal susceptibility exist within Fusarium in this setting.

Fusarium solani keratitis: role of antifungal susceptibility testing and identification to the species level for proper management

ABSTRACT We report a patient with fungal keratitis caused by a multiresistant Fusarium solani in a tertiary care hospital located in southern Brazil. A 55-year-old man with a history of ocular trauma presented with keratitis in left eye. The patient has a complicated clinical course and failed to respond to local and systemic antifungal treatment, and required eye enucleation. Despite multiple topical, intraocular and systemic antifungal treatments, hyphal infiltration persisted in the corneal transplant causing continuous recurrences. The cultures of corneal biopsy scrapings were positive for Fusarium spp. The organism was identified to species level by multi-locus sequencing for translation elongation factor 1 alpha (EF-1α), and RNA polymerase II subunit (RPB2). In vitro antifungal susceptibility testing of the isolate by the broth microdilution method, according to CLSI M38-A2, disclosed susceptibility to natamycin and resistance to amphotericin B, voriconazole, itraconazole and fluconazole. Considering previous unsuccessful antifungal treatments due to multiple drug resistance, the eye was enucleated. Our case report illustrates that management of fungal keratitis remains a therapeutic challenge. Optimal treatment for F. solani infection has not yet been established and should include susceptibility testing for different antifungal agents.

Fusarium solani keratitis: role of antifungal susceptibility testing and identification to the species level for proper management.

We report a patient with fungal keratitis caused by a multiresistant Fusarium solani in a tertiary care hospital located in southern Brazil. A 55-year-old man with a history of ocular trauma presented with keratitis in left eye. The patient has a complicated clinical course and failed to respond to local and systemic antifungal treatment, and required eye enucleation. Despite multiple topical, intraocular and systemic antifungal treatments, hyphal infiltration persisted in the corneal transplant causing continuous recurrences. The cultures of corneal biopsy scrapings were positive for Fusarium spp. The organism was identified to species level by multi-locus sequencing for translation elongation factor 1 alpha (EF-1α), and RNA polymerase II subunit (RPB2). In vitro antifungal susceptibility testing of the isolate by the broth microdilution method, according to CLSI M38-A2, disclosed susceptibility to natamycin and resistance to amphotericin B, voriconazole, itraconazole and fluconazole. Considering previous unsuccessful antifungal treatments due to multiple drug resistance, the eye was enucleated. Our case report illustrates that management of fungal keratitis remains a therapeutic challenge. Optimal treatment for F. solani infection has not yet been established and should include susceptibility testing for different antifungal agents.

Antifungal Susceptibility, Morphological and Molecular Characterization of Lasiodiplodia theobromae Isolated from a Patient with Keratitis.

Lasiodiplodia theobromae is a rare ocular pathogen. We report a patient with fungal keratitis caused by L. theobromae. The patient was a 75-year-old male, a farmer with diabetes type II, and no previous history of ocular trauma. Histopathology analysis revealed the presence fungi invading Descemet's membrane of the cornea. The fungus was characterized by septate, highly bulged fungal filaments involving full corneal thickness in the corresponding histopathology specimens. A dematiaceous mold was isolated and initally identified as L. theobromae by microscopic and macroscopic morphology, and further confirmed by PCR-based determination of internal transcribed spacer (ITS) regions of ribosomal DNA. Antifungal susceptibility tests showed sensitivity to amphotericin B (AMB) and voriconazole ( VRC), and resistance to other azoles, including itraconazole (ITC) and fluconazole (FLC). Corneal transplant was performed. Despite in vitro itraconazole resistance, the patient was successfully treated with oral itraconazole, topical voriconazole and natamycin, combined with ocular injections of amphotericin B and voriconazole.

Candida zeylanoides as a new yeast model for lipid metabolism studies: effect of nitrogen sources on fatty acid accumulation.

Lipid homeostasis is well-known in oleaginous yeasts, but there are few non-oleaginous yeast models apart from Saccharomyces cerevisiae. We are proposing the non-oleaginous yeast Candida zeylanoides QU 33 as model. The aim of this study was to investigate the influence of the carbon/nitrogen ratio and the type of nitrogen source upon oil accumulation by this yeast grown on shake flask cultures. The maximum biomass was obtained in yeast extract (2.39 ± 0.19 g/l), followed by peptone (2.24 ± 0.05 g/l), while the highest content of microbial oil (0.35 ± 0.01 g/l) and the maximum lipid yield (15.63%) were achieved with peptone. Oleic acid was the predominant cellular fatty acid in all culture media (>32.23%), followed by linoleic (>15.79%) and palmitic acids (>13.47%). The highest lipid yield using glucose and peptone was obtained at the C/N ratio of 200:1.