A novel 3D culture model of fungal keratitis to explore host-pathogen interactions within the stromal environment.

Fungal keratitis (FK) pathology is driven by both fungal growth and inflammation within the corneal stroma. Standard in vitro infection models ̶ involving co-culture of the pathogen and the corneal cells in tissue culture medium ̶ are sufficient to probe host responses to the fungus; however, they lack the physiological structure and nutrient composition of the stroma to accurately study fungal invasiveness and metabolic processes. We therefore sought to develop a culture model of FK that would allow for both host and fungal cell biology to be evaluated in parallel. Towards this end, we employed a previously described system in which primary human cornea fibroblasts (HCFs) are cultured on transwell membranes, whereupon they secrete a three-dimensional (3D) collagen matrix that resembles the human stroma. We demonstrated that two common mold agents of FK, Fusarium petroliphilum and Aspergillus fumigatus, penetrated into these constructs and caused a disruption of the collagen matrix that is characteristic of infection. HCF morphology appeared altered in the presence of fungus and electron microscopy revealed a clear internalization of fungal spores into these cells. Consistent with this apparent phagocyte-like activity of the HCFs, mRNA and protein levels for several pro-inflammatory cytokines/chemokines (including TNFα, IL-1ß, IL-6, and IL-8) were significantly upregulated compared to uninfected samples. We similarly found an upregulation of several HCF metalloproteases (MMPs), which are enzymes that breakdown collagen during wound healing and may further activate pro-inflammatory signaling molecules. Finally, several fungal collagenase genes were upregulated during growth in the constructs relative to growth in tissue culture media alone, suggesting a fungal metabolic shift towards protein catabolism. Taken together, our results indicate that this 3D-stromal model provides a physiologically relevant system to study host and fungal cell pathobiology during FK.

Fusarium spp. in Loggerhead Sea Turtles (Caretta caretta): From Colonization to Infection.

With the aim of evaluating the presence of Fusarium spp. in sea turtles with and without lesions and assessing the risk factors favoring colonization and/or infection, 74 loggerhead sea turtles (Caretta caretta) admitted to rescue and rehabilitation clinics in Italy were analyzed. The study compared 31 individuals with no apparent macroscopic lesions and 43 individuals with macroscopic lesions. Shell and skin samples were analyzed using Calcofluor white with 10% potassium hydroxide, standard histopathological examination, and fungal cultures. Fusarium spp. were isolated more frequently from animals with superficial lesions (39%) than from those with no macroscopic lesions (16%). Isolates from animals with superficial lesions were Fusarium solani species complex (FSSC) lineages haplotypes 9, 12, and 27 (unnamed lineages), FSSC-2 (Fusarium keratoplasticum), Fusarium oxysporum (27%), and Fusarium brachygibbosum (3%). In contrast, only F. solani haplotypes 9 and 12 were isolated from animals with no macroscopic lesions. The presence of lesions was identified as a risk factor for the occurrence of Fusarium spp. Of the 74 animals, only 7 (9.5%) scored positive on microscopic examination with Calcofluor, and histological examination of those 7 animals revealed necrosis, inflammatory cells, and fungal hyphae in the carapace and skin. The results of this study suggest that fusariosis should be included in the differential diagnosis of shell and skin lesions in sea turtles. Direct examination using Calcofluor and potassium hydroxide was not useful to diagnose the infection. Histopathological examination and fungal culture should be performed to ensure correct treatment and infection control.

Honokiol, magnolol and its monoacetyl derivative show strong anti-fungal effect on Fusarium isolates of clinical relevance.

The antifungal activity of magnolol and honokiol, two naturally occurring hydroxylated biphenyls, and of their synthetic derivatives was evaluated on a collection of representative isolates of Fusarium oxysporum, F. solani and F. verticillioides of clinical and ecological concern. The tested compounds were proposed as a 'natural' alternative to conventional fungicides, even though a larger range of concentrations (5-400 µg/ml) was applied. The activity of magnolol and honokiol was compared with that of terbinafine (0.1-10 µg/ml), and fluconazole (1-50 µg/ml), two fungicides widely used in treating fungal infections on humans. Magnolol showed similar fungicidal activity compared to fluconazole, whereas honokiol was more effective in inhibiting mycelium growth compared to this fungicide on all tested clinical Fusarium spp. isolates. Compared to terbinafine, honokiol showed similar antifungal activity when tested on clinical F. solani isolates, whereas magnolol was less effective at all selected concentrations (5-400 µg/ml). The different position of the phenol-OH group, as well as its protection, explain different in vitro activities between magnolol, honokiol, and their derivatives. Furthermore, magnolol showed mycelium dry weight reduction at a concentration of 0.5 mM when tested on a set of agricultural isolates of Fusaria, leading to complete inhibition of some of them. Magnolol and honokiol are proposed as efficient and safe candidates for treating clinically relevant Fusaria.

Fusarium onychomycoses in Switzerland-A mycological and histopathological study.

Onychomycoses in temperate climates are most commonly due to dermatophytes, particularly Trichophyton rubrum. Non-dermatophyte nail infections are much less frequent, and their diagnosis requires a careful and repeated search for a potential dermatophyte that may have been overgrown in culture. A series of histological slides of suspected onychomycoses with uncommon fungal morphology prompted us to search for non-dermatophytic moulds causing dermatophytosis-like nail infections. Thirty cases were identified by culture as F solani, F oxysporum, F dimerum or F spp, and two more were only diagnosed histopathologically. None of these patients was immunocompromised. Treatment was mostly unsuccessful with terbinafine whereas itraconazole showed a moderately better treatment result; in all cases, a topical ciclopirox nail varnish in a hydroxychitosan base was added.

Role of the Fusarium oxysporum metallothionein Mt1 in resistance to metal toxicity and virulence.

Soil organisms exhibit high tolerance to heavy metals, probably acquired through evolutionary adaptation to contaminated environments. Essentially, metal tolerance in fungi involves several specific and non-specific mechanisms that include metal efflux, metal binding to cell walls, extracellular and intracellular sequestration and complexation with proteins. However, fungi have adopted different strategies to detoxify heavy metals, although species differ in the mechanisms used. In this complex molecular framework, metallothioneins (MTs) are becoming increasingly relevant in metal homeostasis, even though little is known about their role in metal adaptation and virulence in fungal pathogens. With the aim to decipher the function of metallothioneins in the opportunistic fungus Fusarium oxysporum, we have carried out an in silico analysis that revealed the presence of a hypothetical metallothionein (mt1) that has multiple metal responsive elements in its promoter region and conserved cysteine motifs in its coding sequence. Characterization of strain Δmt1 deficient in the mt1 gene revealed higher sensitivity of this mutant to copper, cadmium and zinc compared to the wild type strain (wt). Expression analyses revealed that Zn specifically activates mt1, but the lack of this gene did not lead to a transcriptional up-regulation of genes gapdh and prx, associated with the oxidative stress response. The lack of mt1 did not alter the pathogenic capacity of the fungus, either in tomato plant or in a murine model of systemic infection. Nevertheless, Δmt1 displayed lower resistance to macrophage killing, suggesting a connection between the absence of mt1 and impaired defence capacity against copper and reactive oxygen species.

Performance of 1,3-beta-D-glucan in the diagnosis and monitoring of invasive fusariosis.

Invasive fusariosis (IF) usually presents with high fungal burden at diagnosis, and this may contribute to its high mortality rate. The use 1,3-beta-D-glucan (BDG) may help to establish the diagnosis at an earlier disease stage and to monitor treatment. To evaluate the performance of BDG in the diagnosis of IF and its kinetics in relation to the outcome, we retrospectively tested serum samples of 13 cases of IF, analysed the temporal relationship between the first positive BDG test and the date of the diagnosis of IF, and the kinetics of BDG in relation to patients' outcome. We selected 13 controls with similar underlying diseases as cases, at least two serum samples stored, and no invasive fungal disease. Twelve patients with IF had at least one positive BDG (median 4, range 1-16). The test was positive before the diagnosis of IF in 11 of the 12 patients (91.6%), at a median of 10 days (range 1-32). The median BDG value increased (from 109 to 316 pg/mL, P = 0.04) in patients who died by day 30, and did not change significantly (99-101 pg/mL, P = 0.60) in survivors. Using two consecutive BDG tests, sensitivity, specificity, and positive and negative predictive values were 85%, 69%, 7% and 99%, respectively. BDG is positive in the majority of patients with IF, usually before the diagnosis, but the low positive predictive value limits its use to diagnose IF earlier. Once therapy is started, decreasing BDG values suggests treatment response.

Invasive fusariosis masquerading as extramedullary disease in rapidly progressive acute lymphoblastic leukemia.

Invasive fusariosis (IF) most commonly occurs in patients with hematologic malignancies and severe neutropenia, particularly during concomitant corticosteroid use. Breakthrough infections can occur in high-risk patients despite Aspergillus-active antifungal prophylaxis. We describe a patient with rapid acute lymphoblastic leukemia (ALL) progression who presented with multifocal skin nodules thought to be choloromatous disease. These lesions were ultimately diagnosed as IF and the patient had two simultaneously active disease processes. This case highlights the importance of pathologic diagnosis of new skin lesions in ALL patients, even during leukemia progression, and demonstrates that IF can occur despite normal neutrophil counts and Aspergillus-active prophylaxis.

Effects of intratracheal Fusarium solani inoculation in immunocompetent mice.

Fusariosis is an infection that is caused by fungi of the Fusarium genus. It is the second most common fungus that is associated with human fungal infections, usually in immunocompromised individuals. The incidence of such infections has been increasing, including in immunocompetent hosts. Studies of host-pathogen interactions are scarce, and the pathophysiology of the disease is unknown. One limitation of such studies is the lack of adequate techniques for mammalian infection, in which no standardized protocols have been established with fungi with a focus on the respiratory tract. The aim of the present study was to assess the first 24 h of infection after the intratracheal inoculation of F. solani microconidia in immunocompetent mice. Colony-forming units (CFU) were counted, and histopathological analysis was performed. Under conditions of high fungal burden, F. solani caused lethal tissue damage in the lungs. Under conditions of low fungal burden, the infection was not lethal, but several alterations of pulmonary tissue and the presence of the fungus in the lungs were observed. No evidence of fungal dissemination was found in the kidneys, spleen, liver, or heart 24 h after infection. The present intratracheal model effectively established fungal infection and appears to be suitable for studies of Fusarium spp.

[Successful treatment of disseminated fusariosis in a febrile neutropenic patient with combined antifungal therapy of voriconazol plus amphotericin B deoxycholate]. / Tratamiento exitoso de una fusariosis diseminada en un paciente neutropénico febril con terapia antifúngica combinada de voriconazol más anfotericina B deoxicolato.

We report a case of a patient with acute lymphoblastic leukemia (ALL), who developed a disseminated infection by Fusarium verticillioides during chemotherapy-induced neutropenia. He was successfully treated only after combination therapy with voriconazole plus amphotericin B deoxycolate was used, but not when these compounds were used in an isolated form.

Fusarium oxysporum is an onychomycosis etiopathogenic agent.

AIM: To evaluate and characterize the etiopathogenesis of the fusarial onychomycosis in an ex vivo study through fragments of sterile human nail, without the addition of any nutritional source. MATERIALS & METHODS: The infection and invasion of Fusarium oxysporum in the nail were evaluated by scanning electron microscopy (SEM), CFU, matrix, histopathology and Fourier Transform Infrared Spectrometer coupled to an equipment with diamond accessory (FTIR-ATR). RESULTS: F. oxysporum infected and invaded across the nail, regardless of application face. However, the dorsal nail surface was the strongest barrier, while the ventral was more vulnerable to infection and invasion process. The fungal-nail interaction resulted in the formation of a dense biofilm. CONCLUSION: F. oxysporum infect and invade the healthy human nail, resulting in biofilm formation. Therefore, F. oxysporum is likely a primary onychomycosis agent.

Disseminated fusariosis with cutaneous involvement in hematologic malignancies: report of six cases with high mortality rate

Abstract: Fusariosis is due to inhalation or direct contact with conidia. Clinical presentation depends on host's immunity and can be localized, focally invasive or disseminated. Given the severity of this infection and the possibility for the dermatologist to make an early diagnosis, we report six cases of patients with hematologic malignancies, who developed febrile neutropenia an skin lesions suggestive of cutaneous fusariosis. All patients had skin cultures showing growth of Fusarium solani complex, and they received amphotericin B and voriconazole. As this infection can quickly lead to death, dermatologists play a crucial role in diagnosing this disease.

Disseminated fusariosis with cutaneous involvement in hematologic malignancies: report of six cases with high mortality rate.

Fusariosis is due to inhalation or direct contact with conidia. Clinical presentation depends on host's immunity and can be localized, focally invasive or disseminated. Given the severity of this infection and the possibility for the dermatologist to make an early diagnosis, we report six cases of patients with hematologic malignancies, who developed febrile neutropenia an skin lesions suggestive of cutaneous fusariosis. All patients had skin cultures showing growth of Fusarium solani complex, and they received amphotericin B and voriconazole. As this infection can quickly lead to death, dermatologists play a crucial role in diagnosing this disease.

Infection cycle of maize stalk rot and ear rot caused by Fusarium verticillioides.

Fusarium verticillioides, an important maize pathogen produces fumonisins and causes stalk and ear rot; thus, we are aimed to clarify its infection cycle by assessing enhanced green fluorescent protein (EGFP) expression in stalk and ear rot strains. Maize seeds were inoculated with stable and strongly pathogenic transformants. To investigate the degree of infection, inoculated plants were observed under a stereo fluorescence microscope, and affected tissue strains were detected using PCR. We found that both transformants infected maize. Hyphae infected the plants from radical to the stem and extended to the ear and infected ear kernels caused a second infection. This process formed the infection cycle.

Tratamiento exitoso de una fusariosis diseminada en un paciente neutropénico febril con terapia antifúngica combinada de voriconazol más anfotericina B deoxicolato / Successful treatment of disseminated fusariosis in a febrile neutropenic patient with combined antifungal therapy of voriconazol plus amphotericin B deoxycholate

Resumen Presentamos el caso clínico de un paciente con una leucemia linfoblástica aguda (LLA) que desarrolló una fusariosis diseminada por Fusarium verticillioides durante un episodio prolongado de neutropenia febril post quimioterapia. Fue exitosamente tratado cuando se usó terapia combinada de voriconazol más anfotericina B deoxicolato.

We report a case of a patient with acute lymphoblastic leukemia (ALL), who developed a disseminated infection by Fusarium verticillioides during chemotherapy-induced neutropenia. He was successfully treated only after combination therapy with voriconazole plus amphotericin B deoxycolate was used, but not when these compounds were used in an isolated form.

Mycotic Keratitis Caused by Fusarium solani sensu stricto (FSSC5): A Case Series.

Owing to a lack of appropriate diagnostic and therapeutic approaches for mycotic keratitis, approximately one million cases of preventable corneal blindness are reported each year. The number of keratitis cases due to infection with Fusarium is increasing significantly worldwide, many of which are not treated adequately and in a timely manner due to frequent misdiagnosis. In the current report, we describe three cases of keratitis caused by Fusarium solani sensu stricto (FSSC5) from Turkey and The Netherlands, following ocular trauma. The etiological agent of keratitis, FSSC5, identified by sequencing of the partial tef1-α gene, exhibited low minimum inhibitory concentrations (MICs) of 1 µg/mL for amphotericin B and high MICs above the published epidemiological cutoff values for voriconazole (8 µg/mL). Patients were successfully treated with topical amphotericin B and voriconazole with complete recovery.

Infections Caused by Fusarium Species in Pediatric Cancer Patients and Review of Published Literature.

Fusarium species have emerged as responsible for a broad spectrum of infections, including superficial, locally invasive and disseminated ones, especially in the hospital environment. Since there are few reports of invasive and disseminated fusariosis in children, the aim of this study was to report four cases of nosocomial infection caused by this microorganism in children with cancer hospitalized in a public children's hospital located in Brazil. Two of these patients were female and two were male. All patients presented febrile neutropenia, while three patients had acute lymphocytic leukemia and one patient had Wilms' tumor as underlying disease. In two cases, fungi were isolated from blood and identified as Fusarium oxysporum species complex after phenotypic and genotypic studies, while in two other cases fungi were isolated from skin biopsies and identified as Fusarium solani species complex. One patient died 12 days after the onset of cutaneous lesions. All isolates, after susceptibility testing, presented high levels of minimum inhibitory concentration for itraconazole, voriconazole and amphotericin B. Considering the emergence of filamentous fungi as etiologic agents of nosocomial infections, health professionals should be aware of the problems these infections, especially fungal ones, may cause to debilitated patients.

Multi-locus sequence typing provides epidemiological insights for diseased sharks infected with fungi belonging to the Fusarium solani species complex.

Fusarium spp. are saprobic moulds that are responsible for severe opportunistic infections in humans and animals. However, we need epidemiological tools to reliably trace the circulation of such fungal strains within medical or veterinary facilities, to recognize environmental contaminations that might lead to infection and to improve our understanding of factors responsible for the onset of outbreaks. In this study, we used molecular genotyping to investigate clustered cases of Fusarium solani species complex (FSSC) infection that occurred in eight Sphyrnidae sharks under managed care at a public aquarium. Genetic relationships between fungal strains were determined by multi-locus sequence typing (MLST) analysis based on DNA sequencing at five loci, followed by comparison with sequences of 50 epidemiologically unrelated FSSC strains. Our genotyping approach revealed that F. keratoplasticum and F. solani haplotype 9x were most commonly isolated. In one case, the infection proved to be with another Hypocrealian rare opportunistic pathogen Metarhizium robertsii. Twice, sharks proved to be infected with FSSC strains with the same MLST sequence type, supporting the hypothesis the hypothesis that common environmental populations of fungi existed for these sharks and would suggest the longtime persistence of the two clonal strains within the environment, perhaps in holding pools and life support systems of the aquarium. This study highlights how molecular tools like MLST can be used to investigate outbreaks of microbiological disease. This work reinforces the need for regular controls of water quality to reduce microbiological contamination due to waterborne microorganisms.