Disseminated Amphotericin-Resistant Fusariosis in Acute Leukemia Patients: Report of Two Cases

Species Diversity in the Fusarium solani (Neocosmospora) Complex and Their Pathogenicity for Plants and Humans

The Fusarium solani species complex is a large group of soil saprotrophs with a broad adaptive potential, which allows the fungi to exist under various conditions and to parasitize on different hosts. The review analyzes the modern data concerning the genetic peculiarities of species from this complex by the example of F. solani f. sp. pisi and generalizes the data on the most widespread species pathogenic for both plants and humans. The enhanced resistance of the F. solani species complex to the most of modern antifungal agents and the need for novel therapeutic agents against fusariosis has been considered.

An Overview of the Management of the Most Important Invasive Fungal Infections in Patients with Blood Malignancies

In patients with hematologic malignancies due to immune system disorders, especially persistent febrile neutropenia, invasive fungal infections (IFI) occur with high mortality. Aspergillosis, candidiasis, fusariosis, mucormycosis, cryptococcosis and trichosporonosis are the most important infections reported in patients with hematologic malignancies that undergo hematopoietic stem cell transplantation. These infections are caused by opportunistic fungal pathogens that do not cause severe issues in healthy individuals, but in patients with hematologic malignancies lead to disseminated infection with different clinical manifestations. Prophylaxis and creating a safe environment with proper filters and air pressure for patients to avoid contact with the pathogens in the surrounding environment can prevent IFI. Furthermore, due to the absence of specific symptoms in IFI, rapid and accurate diagnosis reduces the mortality rate of these infections and using molecular techniques along with standard mycological methods will improve the diagnosis of disseminated fungal infection in patients with hematologic disorders. Amphotericin B products, extended-spectrum azoles, and echinocandins are the essential drugs to control invasive fungal infections in patients with hematologic malignancies, and according to various conditions of patients, different results of treatment with these drugs have been reported in different studies. On the other hand, drug resistance in recent years has led to therapeutic failures and deaths in patients with blood malignancies, which indicates the need for antifungal susceptibility tests to use appropriate therapies. Life-threatening fungal infections have become more prevalent in patients with hematologic malignancies in recent years due to the emergence of new risk factors, new species, and increased drug resistance. Therefore, in this review, we discuss the different dimensions of the most critical invasive fungal infections in patients with hematologic malignancies and present a list of these infections with different clinical manifestations, treatment, and outcomes.

Inconsistent efficacy of water-soluble amphotericin B for the treatment of Macrorhabdus ornithogaster in a budgerigar (Melopsittacus undulatus) aviary

OBJECTIVE

To assess the efficacy of a commercially available in-water amphotericin B treatment for Macrorhabdus ornithogaster.

DESIGN

Clinical treatment trial.

METHODS

Faecal shedding of 16 naturally infected budgerigars (Melopsittacus undulatus) was monitored while they were being treated using in-water amphotericin B, as per the manufacturer's instructions, for 10 days. Any birds that remained positive after 10 days received a further 10 day course of treatment. All birds were rechecked 16 days after the end of the second treatment period.

RESULTS

At the conclusion of treatment, 11 birds had stopped shedding M. ornithogaster, and 5 birds were still shedding. Sixteen days after the conclusion of the second treatment period, four birds that were negative after 10 days of treatment were shedding again, and two of the birds that were treated for 20 days were shedding. In addition, one bird from each treatment group died after treatment and before follow-up testing.

CONCLUSION

These findings represent a 36% treatment failure, suggesting that treatment with the commercially available, water-soluble amphotericin B has inconsistent efficacy against M. ornithogaster in some budgerigars in Australia and is not effective for eliminating it from budgerigar aviaries.

Fusarium: The versatile pathogen

Fusarium is an emerging human opportunistic pathogen of growing importance, especially among immunosuppressed haematology patients due to an increased incidence of disseminated infections over the past two decades. This trend is expected only to continue due to the advances in medical and surgical technologies that will prolong the lives of the severely ill, making these patients susceptible to rare opportunistic infections. Production of mycotoxins, enzymes such as proteases, angio-invasive property and an intrinsically resistant nature, makes this genus very difficult to treat. Fusarium is frequently isolated from the cornea and less commonly from nail, skin, blood, tissue, Continuous Ambulatory Peritoneal Dialysis (CAPD) fluid, urine and pleural fluid. Conventional microscopy establishes the genus, but accurate speciation requires multilocus sequence typing with housekeeping genes such as internal transcribed spacer, translation elongation factor-1α and RPB1 and 2 (largest and second largest subunits of RNA polymerase), for which expansive internet databases exist. Identifying pathogenic species is of epidemiological significance, and the treatment includes immune reconstitution by granulocyte-colony-stimulating factor, granulocyte macrophage-colony-stimulating factor and a combination of the most active species - specific antifungals, typically liposomal amphotericin-B and voriconazole. However, patient outcome is difficult to predict even with in vitro susceptibility with these drugs. Therefore, prevention methods and antifungal prophylaxis have to be taken seriously for these vulnerable patients by vigilant healthcare workers. The current available literature on PubMed and Google Scholar using search terms 'Fusarium', 'opportunistic invasive fungi' and 'invasive fusariosis' was summarised for this review.

Disseminated cutaneous fusariosis in human immunodeficiency virus-infected patient and dramatic response with oral itraconazole

Fusarium species are known to cause disseminated cutaneous lesions in immunocompromised patients. Some cases of fusariosis are reported in patients infected with the human immunodeficiency virus. There are two reports in such patients with systemic comorbidities like lymphoma, neutropenia and infective port-a-catheter. Another reported patient had systemic fusariosis, without skin involvement. Diagnosis and treatment of cutaneous fusariosis is difficult and resistance to antifungals is a problem. Our patient was at an advanced human immunodeficiency virus infection stage with disseminated cutaneous fusariosis, without any systemic involvement, who responded completely to oral itraconazole.

Sterol 14α-demethylase mutation leads to amphotericin B resistance in Leishmania mexicana

Amphotericin B has emerged as the therapy of choice for use against the leishmaniases. Administration of the drug in its liposomal formulation as a single injection is being promoted in a campaign to bring the leishmaniases under control. Understanding the risks and mechanisms of resistance is therefore of great importance. Here we select amphotericin B-resistant Leishmania mexicana parasites with relative ease. Metabolomic analysis demonstrated that ergosterol, the sterol known to bind the drug, is prevalent in wild-type cells, but diminished in the resistant line, where alternative sterols become prevalent. This indicates that the resistance phenotype is related to loss of drug binding. Comparing sequences of the parasites' genomes revealed a plethora of single nucleotide polymorphisms that distinguish wild-type and resistant cells, but only one of these was found to be homozygous and associated with a gene encoding an enzyme in the sterol biosynthetic pathway, sterol 14α-demethylase (CYP51). The mutation, N176I, is found outside of the enzyme's active site, consistent with the fact that the resistant line continues to produce the enzyme's product. Expression of wild-type sterol 14α-demethylase in the resistant cells caused reversion to drug sensitivity and a restoration of ergosterol synthesis, showing that the mutation is indeed responsible for resistance. The amphotericin B resistant parasites become hypersensitive to pentamidine and also agents that induce oxidative stress. This work reveals the power of combining polyomics approaches, to discover the mechanism underlying drug resistance as well as offering novel insights into the selection of resistance to amphotericin B itself.

Reduced Multidrug Susceptibility Profile Is a Common Feature of Opportunistic Fusarium Species: Fusarium Multi-Drug Resistant Pattern

The resistance among various opportunistic Fusarium species to different antifungal agents has emerged as a cause of public health problems worldwide. Considering the significance of multi-drug resistant (MDR), this paper emphasizes the problems associated with MDR and the need to understand its clinical significance to combat microbial infections. The search platform PubMed/MEDLINE and a review of 32 cases revealed a common multidrug-resistant profile exists, and clinically relevant members of Fusarium are intrinsically resistant to most currently used antifungals. Dissemination occurs in patients with prolonged neutropenia, immune deficiency, and especially hematological malignancies. Amphotericin B displayed the lowest minimum inhibitory concentrarions (MICs) followed by voriconazole, and posaconazole. Itraconazole and fluconazole showed high MIC values, displaying in vitro resistance. Echinocandins showed the highest MIC values. Seven out of ten (70%) patients with neutropenia died, including those with fungemia that progressed to skin lesions. Clinical Fusarium isolates displayed a common MDR profile and high MIC values for the most available antifungal agents with species- and strain-specific differences in antifungal susceptibility. Species identification of Fusarium infections is important. While the use of natamycin resulted in a favorable outcome in keratitis, AmB and VRC are the most used agents for the treatment of fusariosis in clinical settings.

In vitro resistance of clinical Fusarium species to amphotericin B and voriconazole using the EUCAST antifungal susceptibility method

Susceptibility testing using the EUCAST-AFST method against 39 clinical Fusarium strains consecutively collected from local and invasive infections during the last 10years assessed the in vitro activities of amphotericin B (AmB) and triazole antifungal agents. In addition, the susceptibility pattern of 12 reference strains from the CBS-KNAW Fungal Biodiversity Centre (CBS) was evaluated. In particular Fusarium petroliphilum and F. solani sensu lato were involved in disseminated infections and known for treatment failure. AmB displayed the lowest MICs followed by voriconazole VRC, posaconazole (POC). Itraconazole (ITC) showed high MIC values, displaying in vitro resistance. Clinical isolates were significantly (P <0.05) more resistant to AmB, VRC, and POC, than the CBS reference isolates probably due to previous exposure to antifungal therapy. Resistant profiles to AmB and VRC, which are the currently recommended agents in the guidelines for treatments, and a late diagnosis may be associated with high mortality rate in immunocompromised patients. The present antifungal susceptibility profiles showed that species- and strain-specific differences in antifungal susceptibility exist within Fusarium and that susceptibility testing is important and may improve the prognosis of these infections.

Fusariosis in a Patient with Acute Myeloid Leukemia: A Case Report and Review of the Literature

Fusarium spp. causes infections mostly in patients with prolonged neutropenia. We describe the case of a disseminated Fusarium solani infection in a patient with acute myeloid leukemia which never reached complete remission during its clinical course. The patient had profound neutropenia and developed skin nodules and pneumonia in spite of posaconazole prophylaxis. F. solani was isolated from blood and skin biopsy, being identified from its morphology and by molecular methods. By broth dilution method, the strain was resistant to azoles, including voriconazole and posaconazole, and to echinocandins. MIC to amphotericin B was 4 mg/L. The patient initially seemed to benefit from therapy with voriconazole and amphotericin B, but, neutropenia perduring, his clinical condition deteriorated with fatal outcome. All efforts should be made to determine the correct diagnosis as soon as possible in a neutropenic patient and to treat this infection in a timely way, assuming pathogen susceptibility while tests of antimicrobial susceptibility are pending. A review of the most recent literature on invasive fungal infections is reported.

Fatal Cases of Bloodstream Infection by Fusarium solani and Review of Published Literature

Fusarium species are ubiquitously present in environment and are well known as human pathogens with high mortality rate in immunocompromised patients. We report here two cases where immunocompromised patients developed fatal bloodstream infections by this organism. Isolates were further identified by ITS1 region sequencing which confirmed them as Fusarium solani. Antifungal susceptibility testing was done following CLSI M38-A2 guidelines to amphotericin B, fluconazole, itraconazole, voriconazole, posaconazole, caspofungin, and micafungin. Both patients had a fatal outcome and expired of septic shock. Therefore, identification up to species level is of utmost importance as that helps in directing the management of the patient thereby leading to a favourable outcome.

Disseminated fusariosis by Fusarium proliferatum in a patient with aplastic anaemia receiving primary posaconazole prophylaxis - case report and review of the literature

Disseminated fusariosis is a life-threatening, invasive, opportunistic infection in immunocompromised patients, especially those with haematological malignancies. The prognosis is poor because these fungi are resistant to many of the available antifungal agents. We present a case of disseminated fusariosis caused by Fusarium proliferatum in a patient with severe aplastic anaemia complicated by a secondary infection of Aspergillus flavus, with a fatal outcome. We also review the documented Fusarium infections in immunocompromised hosts.

Unpredictable susceptibility of emerging clinical moulds to tri-azoles: review of the literature and upcoming challenges for mould identification

Tri-azoles represent the front-line drugs for the treatment of mould diseases; nevertheless, some emerging moulds, such as Fusarium spp., Scedosporium spp., Mucorales and others, may be less susceptible or resistant to these antifungals. A review of the literature was conducted on the susceptibility of rare moulds to the tri-azoles itraconazole, posaconazole and voriconazole. Particular attention was paid to isolates identified by molecular analyses. The range of susceptibility values described for the three tri-azoles was frequently large (from 0.06 to >16), and a high variability was found within each species; isolates were rarely reported as entirely susceptible to all tri-azoles. In addition, the susceptibility of 76 emerging moulds from our collection (including Hypocreales, Dothideomycetes, Scedosporium spp., Mucorales and rare Aspergillus spp.) to itraconazole and voriconazole was determined by the Clinical and Laboratory Standards Institute (CLSI) M38-A2 and European Committee for Antimicrobial Susceptibility Testing (EUCAST) methods. Susceptibility discrepancies (of two dilutions) were found comparing CLSI and EUCAST for Dothideomycetes; the values for the remaining moulds were similar. More practical, faster and inexpensive susceptibility tools are welcome for testing emerging moulds, as these tests still represent a critical tool to support clinicians on the selection of proper antifungal treatment. The susceptibility of emerging moulds to tri-azoles cannot be predicted exclusively following mould identification, as the isolates' susceptibilities showed highly variable values. Some emerging moulds still remain very difficult to identity, even following standard molecular analyses which result in complex fungal collections. This fact limits the definition of epidemiological cut-offs and clinical breakpoints that are still imperative for emerging moulds.

Fusarium napiforme systemic infection: case report with molecular characterization and antifungal susceptibility tests

Introduction

During the last decades, Fusarium spp. has been reported as a significant cause of disease in humans, especially in immunocompromised patients, who have high risk of invasive life-threatening disease. Fusarium species usually reported as cause of human disease are F. solani, F. oxysporum and F. verticillioides.

Case description

We describe the second case in the literature of disseminated fusariosis caused by Fusarium napiforme, that occurred in a 60-year-old woman with multiple myeloma after subsequent cycles of chemotherapy.

Discussion and Evaluation

We identified the F. napiforme not only by standard morphologic criteria by macroscopic and microscopic characteristics, but also confirmed by molecular biology methods, including sequencing. The antifungal susceptibility of the F. napiforme isolates were tested to seven antifungal drugs; the azoles were the most active drug against all the isolates tested.

Conclusions

Fusarium spp. are of relevance in medical mycology, and their profiles of low susceptibility to antifungal drugs highlight the importance for faster and more accurate diagnostic tests, what can contribute to an earlier and precise diagnosis and treatment.

Preparation and characterization of amorphous amphotericin B nanoparticles for oral administration through liquid antisolvent precipitation

We prepared amphotericin B (AmB) nanoparticles through liquid antisolvent precipitation (LAP) and by freeze-drying to improve the solubility of AmB for oral administration. The LAP was optimized through a single-factor experiment. We determined the effects of surfactants and their concentration, the stirring time, the precipitation temperature, the stirring intensity, the drug concentration and the volume ratio of antisolvent to solvent on the mean particle size (MPS) of the AmB nanoparticles. Increased stirring intensity and precipitation time favored AmB nanoparticles with smaller MPS, but precipitation times exceeding 30 min did not further reduce the MPS. Increased Tween-80 concentration and the drug concentration decreased the MPS of the AmB nanoparticles. Increased precipitation temperature and antisolvent to solvent volume ratio initially decreased the MPS of the AmB nanoparticles, which increased thereafter. Optimum conditions produced AmB nanoparticles with an MPS of 135.1 nm. The AmB nanoparticles were characterized through scanning electron microscopy (SEM), mass spectrometry (MS), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermal gravimetric analysis (TG), solvent residue, drug purity test, and dissolution testing. The analyses indicated that the chemical structure of AmB remained unchanged in the nanoparticles, but the structure was changed from crystalline to amorphous. The residual DMSO in the nanoparticles was 0.24% less than the standard set by the International Conference on Harmonization limit for class III solvents. The AmB nanoparticles exhibited 2.1 times faster dissolution rates and 13 times equilibrium solubility compared with the raw drug. The detection results indicate that the AmB nanoparticles potentially improved the oral absorption of AmB.

Identification of Fusarium from a patient with fungemia after multiple organ injury

Fusarium is a filamentous fungus widely distributed in nature, which is an important opportunistic pathogen and could cause fusariosis both in plants and animals. In human, Fusarium could cause local and disseminated infections both in immunocompetent and immunocompromised patients. We describe here a case of a male patient suffered from multiple organ injury, whose blood fungal culture was positive. The isolate was confirmed as "Fusarium solani" according to the morphology of the fungus and the results of phenotypic and molecular identification.