In vitro interaction of terbinafine with itraconazole against clinical isolates of Scedosporium prolificans

Fusarium species,Scedosporium species, and Lomentospora prolificans: A systematic review to inform the World Health Organization priority list of fungal pathogens

Recognizing the growing global burden of fungal infections, the World Health Organization established a process to develop a priority list of fungal pathogens (FPPL). In this systematic review, we aimed to evaluate the epidemiology and impact of infections caused by Fusarium spp., Scedosporium spp., and Lomentospora prolificans to inform the first FPPL. PubMed and Web of Sciences databases were searched to identify studies published between January 1, 2011 and February 23, 2021, reporting on mortality, complications and sequelae, antifungal susceptibility, preventability, annual incidence, and trends. Overall, 20, 11, and 9 articles were included for Fusarium spp., Scedosporium spp., and L. prolificans, respectively. Mortality rates were high in those with invasive fusariosis, scedosporiosis, and lomentosporiosis (42.9%-66.7%, 42.4%-46.9%, and 50.0%-71.4%, respectively). Antifungal susceptibility data, based on small isolate numbers, showed high minimum inhibitory concentrations (MIC)/minimum effective concentrations for most currently available antifungal agents. The median/mode MIC for itraconazole and isavuconazole were ≥16 mg/l for all three pathogens. Based on limited data, these fungi are emerging. Invasive fusariosis increased from 0.08 cases/100 000 admissions to 0.22 cases/100 000 admissions over the time periods of 2000-2009 and 2010-2015, respectively, and in lung transplant recipients, Scedosporium spp. and L. prolificans were only detected from 2014 onwards. Global surveillance to better delineate antifungal susceptibility, risk factors, sequelae, and outcomes is required.

A case of Scedosporium prolificans pulmonary infection in a patient with acute myeloid leukemia

An elderly woman with a history of myelodysplastic syndrome complicated by cavitary pneumonia treated with antibiotics and antifungal therapy was admitted with severe sepsis and pulmonary opacities on imaging. Pulmonary infection with Scedosporium prolificans, was diagnosed on bronchopulmonary lavage (BAL). This common environmental fungus is known to cause rare but severe infection in immunocompromised hosts. The patient was diagnosed with progression to acute myeloid leukemia during the hospitalization for which chemotherapy was initiated. Despite broadening antifungal therapy, the patient developed multi-organ system failure and died.

Modulators of Candida albicans Membrane Drug Transporters: A Lucrative Portfolio for the Development of Effective Antifungals

The escalating prevalence of membrane drug transporters and drug efflux pumps in pathogenic yeast like Candida albicans necessitates a comprehensive understanding of their roles in MDR. The overexpression of drug transporter families, ABC and MFS, implicated in MDR through drug efflux and poses a significant challenge in the diagnosis and treatment of fungal infection. Various mechanisms have been proposed for MDR; however, the upregulation of ABC and MFS superfamily transporters is most noticeable in MDR. The direct inhibition of these transporters seems an efficient strategy to overcome this problem. The goal of the article is to present an overview of the prospect of utilizing these modulators of C. albicans drug transports as effective antifungal molecules against MDR addressing a critical gap in the field. The review tries to address to prevent drug extrusion by modulating the expression of drug transporters of C. albicans. The review discussed the progress in identifying potent, selective, and non-toxic modulators of these transporters to develop some effective antifungals and overcome MDR. We reviewed major studies in this area and found that recent work has shifted toward the exploration of natural compounds as potential modulators to restore drug sensitivity in MDR fungal cells. The focus of this review is to survey and interpret current research information on modulators of C. albicans drug transporters from natural sources emphasizing those compounds that are potent antifungal agents.

The Addition of Systemic Terbinafine to Antifungal Combination Therapy in the Treatment of Disseminated Drug-Resistant Mold Infections in a National Cancer Institute Comprehensive Cancer Center: A Six-Year Study

Introduction Combination antifungal regimens are frequently employed in the treatment of invasive fungal infections in patients who are immunocompromised, particularly for cancer and transplant patients. Terbinafine is a potential agent of interest for combination regimens. Methods We reviewed data over a six-year period examining patient outcomes in terms of both mortality and distribution of pathogens. The total number of patients in our study was 64. The use of terbinafine versus no terbinafine in combination therapy was assessed. Of the 64 patients analyzed, only 14 received terbinafine. Mortality was calculated for both groups, and demographics were analyzed by descriptive statistics. Results There was no statistical difference in mortality outcomes in either group. The addition of terbinafine was well tolerated and did not appear to result in any undue toxicity concerns. Discussion We wish to draw greater attention to this potential agent within our armamentarium for invasive fungal infections. To our knowledge, the total number of patients in our study, while small, represents the largest reported cohort in the literature to date. Sensitivities are crucial to be obtained for fungal pathogens as this likely undermined the utility of terbinafine in our study with larger than expected numbers of multidrug-resistant Fusarium. With limited patient numbers, a multicenter trial would be beneficial to further examine terbinafine in combination regimens.

Scedosporium boydii finding in an immunocompromised patient and review of the literature

BACKGROUND

Scedosporiasis is an emerging mycosis that has gained importance in recent years due to its worldwide prevalence. It is caused by species of the Scedosporium apiospermum complex. These species can cause opportunistic infections in immunocompromised patients and, occasionally, in immunocompetent patients as well. The high intrinsic antifungal resistance make these infections difficult to manage.

AIMS

The objective of this study was to interpret the mycological findings in a transplant patient, together with the images obtained in the radiological studies, in order to provide an early and effective antifungal therapy.

METHODS

The mycological analysis of samples taken from a heart transplant patient with radiological images suggesting a fungal infection was performed. Computed tomography scan of the head and thorax showed space-occupying lesions in both the frontal lobe and cerebellum, and multiple pulmonary nodules. The nodules were punctured and the samples obtained were analyzed according to the procedures for mycological analysis. The identity of the isolates was confirmed by nucleotide sequencing. Eventually, the antifungal susceptibility was studied.

RESULTS

The fungal isolates obtained, whose identity was confirmed by sequencing, belonged to the species Scedosporium boydii. Injured tissues were surgically removed and a treatment with amphotericin B and voriconazole-minimum inhibitory concentration (MIC) 0.5μg/mL and ≥0.5μg/mL respectively - was administered.

CONCLUSIONS

Although the patient died due to complications of a Klebsiella pneumoniae sepsis refractory to treatment, the progression of the fungal disease, although slow, was favourable in the early phases of the treatment due to a correct diagnosis and the antifungal susceptibility test carried out. Clinical cases of this nature highlight the need to increase the epidemiological study of these microorganisms, as well as the proper treatment of the diseases caused, in order to achieve early diagnoses that reduce the morbidity and mortality of patients.

Scedosporium species and Lomentospora prolificans fungaemia is uniformly fatal in patients with haematological malignancy

Scedosporium and Lomentospora species are environmental moulds that are virulent in immunocompromised hosts and rarely cause bloodstream infection (BSI). Patients with Scedosporium and Lomentospora species BSI were identified by the state public laboratory service in Queensland, Australia, over a 20-year period. Twenty-two incident episodes occurred among 21 residents; one patient had a second episode 321 days following the first. Of these, 18 were Lomentospora prolificans, three were Scedosporium apiospermum complex and one was a nonspeciated Scedosporium species. Seventeen (81%) patients died during their index admission, and all-cause mortality at 30, 90 and 365 days was 73%, 82% and 91% respectively. All 20 patients with haematological malignancy died within 365 days of follow-up with a median time to death of 9 days (interquartile range, 6-20 days) following diagnoses of BSI.

Evolution of antifungals for invasive mold infections in immunocompromised hosts, then and now

INTRODUCTION

The current armamentarium of antifungal agents for invasive mold infections (IMI) has dramatically improved over the last 50 years. Existing therapies are, however, associated with toxicities, drug interactions, and in some cases, therapeutic failures. Novel antifungals are needed to address the increasing prevalence of IMI and the growing threat of antifungal resistance.

AREAS COVERED

We review the history and development of the most commonly used antifungals. We discuss the current consensus guidelines and supporting data for treatment of invasive mold infection (IMI), the role of susceptibility testing, and the niche that novel antifungals could fill. We review the current data for aspergillosis, mucormycosis, and hyalohyphomycosis.

EXPERT OPINION

Robust clinical trial data demonstrating the relative effectiveness of our current antifungal agents for treating IMI outside of A. fumigatus remains limited. Clinical trials are urgently needed to delineate the relationship between MICs and clinical outcomes for existing agents and to better evaluate the invitro and in-vivo aspects of antifungal synergy. Continued international multicenter collaboration and standardized clinical endpoints for trials evaluating both existing and new agents is necessary to advance the field.

Clinical utility of antifungal susceptibility testing

Invasive fungal diseases cause significant morbidity and mortality, in particular affecting immunocompromised patients. Resistant organisms are of increasing importance, yet there are many notable differences in the ability to both perform and interpret antifungal susceptibility testing compared with bacteria. In this review, we will highlight the strengths and limitations of resistance data of pathogenic yeasts and moulds that may be used to guide treatment and predict clinical outcomes.

Exploration of the Antimicrobial Synergy between Selected Natural Substances on Streptococcus mutans to Identify Candidates for the Control of Dental Caries

Dental caries is caused by the buildup of acidic end products that result from the metabolism of dental plaque microbes. Natural products that are widely available could be used as an alternative or adjunctive anti-caries therapy. Sometimes, when two products are used together, they yield a more powerful antimicrobial effect than the anticipated additive effect. These synergistic combinations are often better treatment options because individual agents may not have sufficient antimicrobial action to be effective when used alone. Cranberries contain phenolic compounds like proanthocyanidins (PAC) that disrupt biofilm formation. Manuka honey has high concentrations of the agent methylglyoxal (MGO), which is cariostatic. Because these agents have varied modes of antimicrobial action, they show potential for possible synergistic effects when paired. Various cranberry extracts were tested pairwise with manuka honey or MGO by well-diffusion assays and 96-well checkerboard assays in the presence of Streptococcus mutans to test for synergy. Synergy was demonstrated in cranberry extracts Type R and RE when paired with manuka honey and MGO. The synergistic combinations found in this research thus can be considered candidates for the formulation of a dentifrice that could be used to inhibit the formation of dental plaque and thereby avoid the development of caries. IMPORTANCE The emergence of bacteria resistant to antimicrobial agents has led to a shortage of options when choosing effective treatment agents. Further, some antibiotics used at therapeutic doses can produce undesired side effects. An alternative to traditional antibiotics, natural antimicrobial agents can be used in combination to obtain synergistic outcomes without subjecting the patient to toxic or irritating doses of individual agents. Streptococcus mutans growth and biofilm formation are major contributors to the formation of dental caries. In this study, a synergistic combination of Manuka honey and cranberry extracts gives evidence that it can be used as an alternative or adjunctive anti-caries therapy.

Augmenting Azoles with Drug Synergy to Expand the Antifungal Toolbox

Fungal infections impact the lives of at least 12 million people every year, killing over 1.5 million. Wide-spread use of fungicides and prophylactic antifungal therapy have driven resistance in many serious fungal pathogens, and there is an urgent need to expand the current antifungal arsenal. Recent research has focused on improving azoles, our most successful class of antifungals, by looking for synergistic interactions with secondary compounds. Synergists can co-operate with azoles by targeting steps in related pathways, or they may act on mechanisms related to resistance such as active efflux or on totally disparate pathways or processes. A variety of sources of potential synergists have been explored, including pre-existing antimicrobials, pharmaceuticals approved for other uses, bioactive natural compounds and phytochemicals, and novel synthetic compounds. Synergy can successfully widen the antifungal spectrum, decrease inhibitory dosages, reduce toxicity, and prevent the development of resistance. This review highlights the diversity of mechanisms that have been exploited for the purposes of azole synergy and demonstrates that synergy remains a promising approach for meeting the urgent need for novel antifungal strategies.

Diagnosis, treatment, and outcome in a dog with systemic Mycoleptodiscus indicus infection

Objective

Describe the diagnosis, clinical course, and management of a dog with systemic Mycoleptodiscus indicus infection.

Case Summary

A 5‐year‐old male neutered Giant Schnauzer presented with left eye anterior uveitis, peripheral lymphadenopathy, hyperglobulinemia, anemia, and thrombocytopenia. A diagnosis of M. indicus infection was made based on histopathology and PCR. Treatment with itraconazole and terbinafine resulted in resolution of the hyperglobulinemia, anemia, thrombocytopenia, and peripheral lymphadenopathy. No evidence of fungal organisms was identified on lymph node, liver, or ocular histopathology after 7 months of treatment.

New or Unique Information Provided

This case is the first report of a systemic M. indicus infection in an apparently immunocompetent dog. Clinical resolution was achieved with systemic itraconazole and terbinafine.

Terbinafine Hydrochloride Combined With Itraconazole for Fungal Skin Diseases: A Randomized Controlled Trial

BACKGROUND

Terbinafine and itraconazole are the common antifungal drugs in clinic. In vitro experiments proved that terbinafine combined with itraconazole achieves better antifungal effects. However, clinical study addressing this issue was still scarce.

STUDY QUESTION

Terbinafine combined with itraconazole achieves better therapeutic effects in fungal skin diseases.

STUDY DESIGN

Approximately 178 patients with fungal skin diseases from Meizhou People's Hospital, China, between October 2016 and October 2017 were admitted to this study. Patients were randomly distributed to 3 groups by randomly selecting random numbers and were treated with terbinafine, itraconazole, monotherapy, or combined therapy. Both patients and study investigators were unaware of grouping situations during experiments. Fifteen patients were excluded due to poor compliance, and 11 patients were excluded due to incomplete data. Finally, 152 patients were analyzed for this study.

MEASURES AND OUTCOMES

The therapeutic effects were evaluated by clinic symptom scores, mycology examination, the cure rate, and the cure time. Adverse events, relapse of disease, and patient's satisfaction level were recorded during follow-up.

RESULTS

In the terbinafine + itraconazole group, at 14 days after treatment, the symptom scores were significantly decreased, compared with the terbinafine or itraconazole group (P1 < 0.05, P2 < 0.05). At 28 days after treatment, the fungal infection of 37 patients was eradicated, which were significantly more than 26 patients in the terbinafine group and 19 patients in the itraconazole group (P1 < 0.05, P2 < 0.05). The terbinafine + itraconazole group also exhibited 100% cure rate of patients with fungal skin diseases, shorter cure time, and increased number of cured patients during the same treatment period, which was better than terbinafine or itraconazole monotherapy (P1 < 0.05, P2 < 0.05). In addition, no adverse events and no relapse of fungal disease were reported in the terbinafine + itraconazole group during follow-up. Ninety-eight percent patients were satisfied with the therapeutic effects of combined treatment.

CONCLUSIONS

Compared with terbinafine or itraconazole monotherapy, terbinafine + itraconazole combined treatment achieves better therapeutic effects in fungal skin diseases.

Antifungal Susceptibility Profiles and Drug Resistance Mechanisms of Clinical Lomentospora prolificans Isolates

Lomentospora prolificans is an opportunistic fungal pathogen with low susceptibility to current antifungal drugs. Here, we tested the in vitro susceptibility of 8 drugs against 42 clinical L. prolificans isolates. All isolates showed high MICs to voriconazole (MIC₉₀>16 μg/ml), itraconazole (MIC₉₀>16 μg/ml), posaconazole (MIC₉₀>16 μg/ml), isavuconazole (MIC₉₀>16 μg/ml), amphotericin B (MIC₉₀>16 μg/ml), and terbinafine (MIC₉₀>64 μg/ml) and high minimum effective concentrations (MECs) to micafungin (MEC₉₀>8 μg/ml), with the exception of miltefosine showing an MIC₉₀ value of 4 μg/ml. We examined six different in vitro drug combinations and found that the combination of voriconazole and terbinafine achieved the most synergistic effort against L. prolificans We then annotated the L. prolificans whole genome and located its Cyp51 and Fks1 genes. We completely sequenced the two genes to determine if any mutation would be related to azole and echinocandin resistance in L. prolificans We found no amino acid changes in Cyp51 protein and no tandem repeats in the 5' upstream region of the Cyp51 gene. However, we identified three intrinsic amino acid residues (G138S, M220I, and T289A) in the Cyp51 protein that were linked to azole resistance. Likewise, two intrinsic amino acid residues (F639Y, W695F) that have reported to confer echinocandin resistance were found in Fks1 hot spot regions. In addition, three new amino acid alterations (D440A, S634R, and H1245R) were found outside Fks1 hot spot regions, and their contributions to echinocandin resistance need future investigation. Overall, our findings support the notion that L. prolificans is intrinsically resistant to azoles and echinocandins.

Therapeutic Challenges of Non-Aspergillus Invasive Mold Infections in Immunosuppressed Patients

While Aspergillus spp. remain the major cause of invasive mold infections in hematologic cancer patients and transplant recipients, other opportunistic molds, such as Mucorales, Fusarium, and Scedosporium spp. are increasingly encountered in an expanding population of patients with severe and prolonged immunosuppression. High potential for tissue invasion and dissemination, resistance to multiple antifungals and high mortality rates are hallmarks of these non-Aspergillus invasive mold infections (NAIMIs). Assessment of drug efficacy is particularly difficult in the complex treatment scenarios of NAIMIs. Specifically, correlation between in vitro susceptibility and in vivo responses to antifungals is hard to assess, in view of the multiple, frequently interrelated factors influencing outcomes, such as pharmacokinetic/pharmacodynamic parameters determining drug availability at the site of infection, the net state of immune suppression, delay in diagnosis, or surgical debulking of infectious foci. Our current therapeutic approach of NAIMIs should evolve toward a better integration of the dynamic interactions between the pathogen, the drug and the host. Innovative concepts of experimental research may consist in manipulating the host immune system to induce a specific antifungal response or targeted drug delivery. In this review, we discuss the challenges in the management of NAIMIs and provide an update about the latest advances in diagnostic and therapeutic approaches.

Scedosporium and Lomentospora: an updated overview of underrated opportunists

Species of Scedosporium and Lomentospora are considered as emerging opportunists, affecting immunosuppressed and otherwise debilitated patients, although classically they are known from causing trauma-associated infections in healthy individuals. Clinical manifestations range from local infection to pulmonary colonization and severe invasive disease, in which mortality rates may be over 80%. These unacceptably high rates are due to the clinical status of patients, diagnostic difficulties, and to intrinsic antifungal resistance of these fungi. In consequence, several consortia have been founded to increase research efforts on these orphan fungi. The current review presents recent findings and summarizes the most relevant points, including the Scedosporium/Lomentospora taxonomy, environmental distribution, epidemiology, pathology, virulence factors, immunology, diagnostic methods, and therapeutic strategies.

Lomentospora prolificans vertebral osteomyelitis with spinal epidural abscess in an immunocompetent woman: Case report and literature review

Lomentospora prolificans is a rare cause of vertebral osteomyelitis. We report a case of L. prolificans thoracic vertebral osteomyelitis with spinal epidural abscess in a patient without apparent immunodeficiency. Clinical manifestations and radiographic findings could not distinguish from other etiologic agents. Treatment is also challenging because L. prolificans is usually resistant to antifungal agents. The patient underwent surgical debridement and has been receiving a prolonged combination of antifungal therapy to prevent an infection relapse.

Pathobiology of Lomentospora prolificans: could this species serve as a model of primary antifungal resistance?

The number of fungal isolates resistant to antifungal drugs has increased dramatically over the last few years and has become an important concern for clinicians. Among these isolates, fungi showing multidrug resistance are particularly worrying because of the difficulties associated with their treatment. These factors hamper the successful recovery of patients and drastically raise mortality rates. Antifungal resistance is multifactorial and several mechanisms in different fungi have been described. There is a need to study these mechanisms in depth; however, the study of antifungal drug resistance separately for each individual species makes progress in the field very slow and tedious. The selection of a multiresistant microorganism as a model for understanding resistance mechanisms and extrapolating the results to other species could help in the search for a solution. In this mini-review, we describe the pathobiology of Lomentospora (Scedosporium) prolificans, paying special attention to its intrinsic resistance to all currently available antifungal agents. The characteristics of L. prolificans offer several advantages: the possibility of using a single microorganism for the study of resistance to different drugs, even cases of double and triple resistance; it is biologically safe for society in general as no new genetically-modified strains are needed for the experiments; it is homologous with other fungal species, and there is repetitiveness between different strains. In conclusion, we propose L. prolificans as a candidate for consideration as a fungal model for the study of resistance mechanisms against antifungal agents.

Dematiaceous Molds

Dematiaceous fungi are the cause of phaeohyphomycosis, a term that encompasses many clinical syndromes, from local infections due to trauma to widely disseminated infection in immunocompromised patients. These fungi are unique owing to the presence of melanin in their cell walls, which imparts the characteristic dark color to their spores and hyphae. Melanin may also be a virulence factor. Local infection may be cured with excision alone, whereas systemic disease is often refractory to therapy. Azoles have the most consistent in vitro activity. Further studies are needed to better understand the pathogenesis and treatment of these uncommon infections.

In vitro combinations of natamycin with voriconazole, itraconazole and micafungin against clinical Fusarium strains causing keratitis

OBJECTIVES

Fusarium species cause a broad spectrum of infections, from superficial to disseminated disease. Because Fusarium species are intrinsically resistant to most antifungal drugs, new approaches are needed. The aim of the present study was to evaluate the in vitro combination of natamycin with currently used antifungal drugs.

METHODS

The in vitro interactions of combinations between natamycin and voriconazole, itraconazole and micafungin applied to 20 clinical Fusarium strains (members of Fusarium falciforme, Fusarium napiforme, Fusarium petroliphilum, Fusarium proliferatum, Fusarium pseudensiforme and Fusarium sacchari) were evaluated using a chequerboard microdilution method. The MICs of all drugs alone and in combination were determined visually after 48 h and interactions were assessed using fractional inhibitory concentration index (FICI) analysis.

RESULTS

MICs of voriconazole and natamycin alone were 4 to >16 and 4-8 mg/L, respectively. Values were reduced 3.5-10-fold to 0.02-0.5 mg/L and 0.5-5-fold to 0.13-2 mg/L in combination, for the currently used antifungals and natamycin, respectively, demonstrating additive to synergistic interactions. The combinations natamycin/voriconazole, natamycin/itraconazole and natamycin/micafungin were synergistic (FICI ≤0.5) for 70%, 15% and 5% of the strains, respectively. No antagonism was found.

CONCLUSIONS

The combination of natamycin with voriconazole was strongly synergistic at clinically achievable serum concentrations.

ESCMID and ECMM joint guidelines on diagnosis and management of hyalohyphomycosis: Fusarium spp., Scedosporium spp. and others

Mycoses summarized in the hyalohyphomycosis group are heterogeneous, defined by the presence of hyaline (non-dematiaceous) hyphae. The number of organisms implicated in hyalohyphomycosis is increasing and the most clinically important species belong to the genera Fusarium, Scedosporium, Acremonium, Scopulariopsis, Purpureocillium and Paecilomyces. Severely immunocompromised patients are particularly vulnerable to infection, and clinical manifestations range from colonization to chronic localized lesions to acute invasive and/or disseminated diseases. Diagnosis usually requires isolation and identification of the infecting pathogen. A poor prognosis is associated with fusariosis and early therapy of localized disease is important to prevent progression to a more aggressive or disseminated infection. Therapy should include voriconazole and surgical debridement where possible or posaconazole as salvage treatment. Voriconazole represents the first-line treatment of infections due to members of the genus Scedosporium. For Acremonium spp., Scopulariopsis spp., Purpureocillium spp. and Paecilomyces spp. the optimal antifungal treatment has not been established. Management usually consists of surgery and antifungal treatment, depending on the clinical presentation.

Therapy of infections caused by dematiaceous fungi

Dematiaceous fungi are responsible for a wide variety of clinical syndromes, from local infections due to trauma, to disseminated infection in immunocompromised patients. These fungi are unique owing to the presence of melanin in their cell walls, which imparts the characteristic dark color to their spores and hyphae. Melanin may also be a virulence factor in these fungi. Therapy depends upon the clinical syndrome. Local infection may be cured with excision alone, while systemic disease is often refractory to therapy. Azoles such as itraconazole and voriconazole have the most consistent in vitro activity, although newer agents may also play a role in therapy in the future.

ScedosporiumSpecies Infections and Treatments

Scedosporium species are now increasingly isolated from immunocompromised and immunocompetent patients. Unfortunately, Scedosporium species infections are generally resistant to amphotericin B, and S. prolificans strains are particularly resistant to presently-available antifungal agents. Here we review the microbiology, expanding epidemiology, numerous clinical presentations, and diagnostic tools available for Scedosporium species infections. Finally, we detail the available in vitro, animal model, and clinical data on the treatment of Scedosporium species infections with special emphasis on the role of newer antifungal therapies for these recalcitrant infections.

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.

Infection and colonisation due to Scedosporium in Northern Spain. An in vitro antifungal susceptibility and molecular epidemiology study of 60 isolates

Since the latest taxonomical changes in the genus Scedosporium by Gilgado et al. in 2010, no species-specific studies on epidemiology and antifungal susceptibility patterns (AFSP) have so far been published. This study aimed to provide qualitative epidemiological data of Scedosporium spp. isolated from cystic fibrosis (CF) patients and immunocompromised patients from Northern Spain. Isolates were identified by using amplified fragment length polymorphism (AFLP), and species-specific AFSP were generated for all currently available antifungal compounds. AFLP was a useful tool for identification to species-level and for the discrimination of inter- and intra-patient isolates. Scedosporium prolificans represents the most prevalent species in the respiratory tract of CF patients and immunocompromised patients in Northern-Spain, followed by Pseudallescheria boydii, P. apiosperma, and P. ellipsoidea. CF patients were exclusively colonised with either P. boydii or S. prolificans. Patients were colonised over years exclusively with isolates affiliated to one species, but some patients were colonised with multiple strains with different AFSP. The sum of those co-colonising strains in one patient, may appear in vitro and in vivo as a multi-resistant S. prolificans isolate, as strains are morphologically identical and might therefore be regarded as only one strain. A majority of Scedosporium strains (with exception of S. prolificans) were found susceptible for voriconazole and micafungin.

Species-specific antifungal susceptibility patterns of Scedosporium and Pseudallescheria species

Since the separation of Pseudallescheria boydii and P. apiosperma in 2010, limited data on species-specific susceptibility patterns of these and other species of Pseudallescheria and its anamorph Scedosporium have been reported. This study presents the antifungal susceptibility patterns of members affiliated with both entities. Clinical and environmental isolates (n = 332) from a wide range of sources and origins were identified down to species level and tested according to CLSI M38-A2 against eight antifungal compounds. Whereas P. apiosperma (geometric mean MIC/minimal effective concentration [MEC] values of 0.9, 2.4, 7.4, 16.2, 0.2, 0.8, 1.5, and 6.8 μg/ml for voriconazole, posaconazole, isavuconazole, itraconazole, micafungin, anidulafungin, caspofungin, and amphotericin B, respectively) and P. boydii (geometric mean MIC/MEC values of 0.7, 1.3, 5.7, 13.8, 0.5, 1.4, 2.3, and 11.8 μg/ml for voriconazole, posaconazole, isavuconazole, itraconazole, micafungin, anidulafungin, caspofungin, and amphotericin B, respectively) had similar susceptibility patterns, those for S. aurantiacum, S. prolificans, and S. dehoogii were different from each other. Voriconazole was the only drug with significant activity against S. aurantiacum isolates. The MIC distributions of all drugs except voriconazole did not show a normal distribution and often showed two subpopulations, making a species-based prediction of antifungal susceptibility difficult. Therefore, antifungal susceptibility testing of all clinical isolates remains essential for targeted antifungal therapy. Voriconazole was the only compound with low MIC values (MIC(90) of ≤ 2 μg/ml) for P. apiosperma and P. boydii. Micafungin and posaconazole showed moderate activity against the majority of Scedosporium strains.

Melanized fungi in human disease

Melanized or dematiaceous fungi are associated with a wide variety of infectious syndromes, including chromoblastomycosis, mycetoma, and phaeohyphomycosis. [corrected]. Many are soil organisms and are generally distributed worldwide, though certain species appear to have restricted geographic ranges. Though they are uncommon causes of disease, melanized fungi have been increasingly recognized as important pathogens, with most reports occurring in the past 20 years. The spectrum of diseases with which they are associated has also broadened and includes allergic disease, superficial and deep local infections, pneumonia, brain abscess, and disseminated infection. For some infections in immunocompetent individuals, such as allergic fungal sinusitis and brain abscess, they are among the most common etiologic fungi. Melanin is a likely virulence factor for these fungi. Diagnosis relies on careful microscopic and pathological examination, as well as clinical assessment of the patient, as these fungi are often considered contaminants. Therapy varies depending upon the clinical syndrome. Local infection may be cured with excision alone, while systemic disease is often refractory to therapy. Triazoles such as voriconazole, posaconazole, and itraconazole have the most consistent in vitro activity. Further studies are needed to better understand the pathogenesis and optimal treatment of these uncommon infections.

Defining fractional inhibitory concentration index cutoffs for additive interactions based on self-drug additive combinations, Monte Carlo simulation analysis, and in vitro-in vivo correlation data for antifungal drug combinations against Aspergillus fumigatus

The fractional inhibitory concentration (FIC) index range of 0.5 to 4 that is commonly used to define additivity results in no interactions in most combination studies of antifungal agents. These results may differ from those of in vivo studies, where positive and negative interactions may be observed. We reassessed this in vitro FIC index range based on (i) the experimental variation of the checkerboard technique using multiple replicates, (ii) the ability to correctly determine purely additive self-drug and two-drug antagonistic combinations of amphotericin B (AMB) and voriconazole (VRC), (iii) Monte Carlo simulation analysis, and (iv) in vitro-in vivo correlation using experimental models of invasive pulmonary aspergillosis against the same Aspergillus fumigatus isolate based on visual, spectrophotometric, and colorimetric determinations of FICs after 24 and 48 h of incubation. FICs obtained after 24 h of incubation ranged from 0.5 to 1.25 for the self-drug additive combinations of AMB plus AMB and VRC plus VRC and from 2.25 to 4.25 for the antagonistic combination of AMB plus VRC. Monte Carlo simulation analysis showed that self-drug combinations were correctly classified as additive and that the combination of AMB plus VRC was correctly classified as antagonistic for >85% of the simulated FICs when deviation of the 95% confidence interval (CI) of replicate FICs from the additivity range of 1 to 1.25 was used to assess interactions after 24 h. In vitro-in vivo correlation analysis showed that the 95% CIs of the FICs of the in vivo synergistic combination anidulafungin plus VRC determined after 24 h were lower than 1 and the 95% CIs of the FICs of the in vivo antagonistic combination AMB plus ravuconazole were higher than 1.25. Adequate insight into weak pharmacodynamic interactions with in vivo relevance may be obtained by demonstrating that triplicate FICs at 24 h are outside an inclusive additivity range of 1 to 1.25.

Invasive infection caused by Pseudallescheria boydii in an immunocompetent patient

Pseudallescheria boydii is a saprophytic fungus frequently isolated from agricultural soil and polluted water. Disseminated and invasive infections with this organism are seen primarily in the immunocompromised host. We present an unusual case of invasive P. boydii infection in an immunocompetent patient admitted to our hospital with clinical, laboratory and ECG findings of a possible acute myocardiac infarction. Six hours after admission without treatment with thrombolytic agents she presented with a right hemiparesis and loss of consciousness; a CT scan showed a cerebral hemorrhage. She was treated with dexamethasone i.v. 32 mg per day. She was not incubated. Two blood cultures taken the 15th and 16th day of hospitalization, respectively, revealed a filamentous fungus which was identified by CBS as P. boydii. The pathologic examination of one nodule showed hyphae of fungi. Despite the administration of amphotericin B the patient died one week later.

Recommendations for the treatment of established fungal infections

Evidence-based guidelines for the treatment of established fungal infections in the adult haematology/oncology setting were developed by a national consensus working group representing clinicians, pharmacists and microbiologists. These updated guidelines replace the previous guidelines published in the Internal Medicine Journal by Slavin et al. in 2004. The guidelines are pathogen-specific and cover the treatment of the most common fungal infections including candidiasis, aspergillosis, cryptococcosis, zygomycosis, fusariosis, scedosporiosis, and dermatophytosis. Recommendations are provided for management of refractory disease or salvage therapies, and special sites of infections such as the cerebral nervous system and the eye. Because of the widespread use newer broad-spectrum triazoles in prophylaxis and empiric therapy, these guidelines should be implemented in concert with the updated prophylaxis and empiric therapy guidelines published by this group.

Successful treatment for chromoblastomycosis caused by Fonsecaea monophora: a report of three cases in Guangdong, China

Fonsecaea pedrosoi is the most prevalent aetiological agent of chromoblastomycosis. Fonsecaea monophora is a new species segregated from Fonsecaea pedrosoi. Herein, we report on three cases of chromoblastomycosis caused by F. monophora that were successfully treated with terbinafine and/or itraconazole. Clinical characteristics and mycological parameters are described. Two of the three patients underwent combination therapy with itraconazole and terbinafine during early stages of treatment and were completely healed in a relatively short course of treatment.

Infections caused by Scedosporium spp

Scedosporium spp. are increasingly recognized as causes of resistant life-threatening infections in immunocompromised patients. Scedosporium spp. also cause a wide spectrum of conditions, including mycetoma, saprobic involvement and colonization of the airways, sinopulmonary infections, extrapulmonary localized infections, and disseminated infections. Invasive scedosporium infections are also associated with central nervous infection following near-drowning accidents. The most common sites of infection are the lungs, sinuses, bones, joints, eyes, and brain. Scedosporium apiospermum and Scedosporium prolificans are the two principal medically important species of this genus. Pseudallescheria boydii, the teleomorph of S. apiospermum, is recognized by the presence of cleistothecia. Recent advances in molecular taxonomy have advanced the understanding of the genus Scedosporium and have demonstrated a wider range of species than heretofore recognized. Studies of the pathogenesis of and immune response to Scedosporium spp. underscore the importance of innate host defenses in protection against these organisms. Microbiological diagnosis of Scedosporium spp. currently depends upon culture and morphological characterization. Molecular tools for clinical microbiological detection of Scedosporium spp. are currently investigational. Infections caused by S. apiospermum and P. boydii in patients and animals may respond to antifungal triazoles. By comparison, infections caused by S. prolificans seldom respond to medical therapy alone. Surgery and reversal of immunosuppression may be the only effective therapeutic options for infections caused by S. prolificans.

Use of terbinafine in rare and refractory mycoses

Terbinafine is the only systemic allylamine antifungal currently available. Its mechanism of action is unique and sets it apart from other agents. Although it is primarily used for dermatophyte infections, such as onychomycosis and tinea pedis, terbinafine has broad in vitro activity against a variety of non-dermatophyte fungal pathogens, including Candida spp. and many molds. In addition, synergistic activity is noted with other antifungals, notably triazoles. Multiple case reports exist of its use for unusual and refractory fungal infections, but no systematic review is available. We review the current literature with regard to in vitro data and clinical experience with terbinafine in the treatment of rare and refractory mycoses.

In vitro activities of 35 double combinations of antifungal agents against Scedosporium apiospermum and Scedosporium prolificans

Activities of 35 combinations of antifungal agents against Scedosporium spp. were analyzed by a checkerboard microdilution design and the summation of fractional concentration index. An average indifferent effect was detected apart from combinations of azole agents and echinocandins against Scedosporium apiospermum. Antagonism was absent for all antifungal combinations against both species.

In vitro activities of voriconazole, itraconazole, and terbinafine alone or in combination against Pythium insidiosum isolates from Brazil

We evaluated the in vitro activities of voriconazole, itraconazole, and terbinafine against 30 clinical isolates of Pythium insidiosum using a checkerboard macrodilution method. The combined activity of terbinafine plus itraconazole or plus voriconazole was synergic against 17% of the strains. Antagonism was not observed.

Dematiaceous fungi

Dematiaceous fungi are responsible for a wide variety of infectious syndromes. They are often found in soil and generally distributed worldwide. This suggests that most if not all individuals are exposed to them, presumably from inhalation or trauma. In recent years, these fungi have been increasingly recognised as important pathogens. The spectrum of diseases they are associated with has also broadened and includes superficial and deep local infections, allergic disease, pneumonia, brain abscess and disseminated infection. For some infections in immunocompetent individuals, such as allergic fungal sinusitis and brain abscess, they are among the most common aetiological agents. These fungi may have unique pathogenic mechanisms owing to the presence of melanin in their cell walls, which imparts the characteristic dark colour to their spores and hyphae. Diagnosis rests on careful microscopical and pathological examination, as there are no simple laboratory tests to reliably identify these fungi. Therapy depends upon the clinical syndrome. Local infection may be cured with excision alone, while systemic disease is often refractory to therapy. Azoles such as itraconazole and voriconazole have the most consistent in vitro activity, though there is more clinical experience with itraconazole. Further studies are needed to better understand the pathogenesis and optimal treatment of these uncommon infections.

Phaeohyphomycosis

Phaeohyphomycosis is an uncommon infection, but has become increasingly recognized in a wide variety of clinical syndromes. Many species are associated with human infection, though a few are responsible for most cases. Because these are typically soil organisms and common laboratory contaminants, they are often disregarded from clinical specimens as non-pathogenic. The clinical setting in which they are isolated, however, should always be carefully considered before making decisions regarding therapy. Bipolaris and Curvularia are often associated ith allergic disease. Diagnosis depends on a high degree of clinical suspicion and appropriate pathologic and mycologic examination of clinical specimens. Therapy is evolving for many of the clinical syndromes described, and randomized clinical trials are unlikely given the sporadic nature of cases. Case reporting of successful and unsuccessful clinical experiences is important in attempting to better define optimal therapy for the more refractory infections. Itraconazole and voriconazole demonstrate the most consistent in vitro activity against this group of fungi. Itraconazole should be considered the drug of choice for most situations, given the greater clinical experience associated with its use for these infections. Given the lack of comparative clinical data, however, decisions over which azole to use in particular setting are largely empiric. Much additional work is needed to better understand the pathogenic mechanisms underlying phaeohyphomycosis and optimize therapy for these often refractory infections.

Successful treatment of multiple Pseudallescheria boydii brain abscesses and ventriculitis/ependymitis in a 2-year-old child after a near-drowning episode

RATIONALE

We report on a cerebral infection by Pseudallescheria boydii in a 21-month-old boy after a near-drowning episode. MRI revealed multiple (> 60) intracerebral abscesses.

METHODS

The surgical therapy included CSF drainage and microsurgical resection of one abscess for microbiological diagnosis. Antimycotic therapy included terbinafine and intraventricular caspofungin in addition to voriconazole.

RESULTS

Systemic side effects of chemotherapy were not observed. After placement of a ventriculoperitoneal shunt, the boy was transferred to a rehabilitation clinic and improved neurologically. After 20 months, MRI documented a continuing remission of the disease.

CONCLUSION

Our case proves that an aggressive treatment should be undertaken and can be successful in CNS pseudallescheriasis.

Cerebral scedosporiosis: an emerging fungal infection in severe neutropenic patients: CT features and CT pathologic correlation

Scedosporium prolificans is an emerging opportunistic fungal agent encountered in severely neutropenic patients. The purpose of this paper is to describe the main cranial CT findings from a retrospective review of six patients (four men and two women, 18-66 years old) afflicted with disseminated infection by S. prolificans with neurological symptoms. They were severely neutropenic and presented with severe respiratory failure and conscience deterioration, with a subsequent 100% mortality. The final diagnosis was established by autopsy (performed in five patients) and blood culture findings. Cranial CT showed multiple low-density lesions in four patients without contrast enhancement located in the basal ganglia and corticomedullary junction. Autopsy findings of these lesions demonstrated necrosis and hyphae proliferation inside brain infarcts. Also, two of the patients had a subarachnoid hemorrhage, but angiography could not be performed. CT and autopsy findings were fairly similar to those encountered in cerebral aspergillosis; however, possibly because of its rapid and fatal evolution, no edema or ring enhancing lesions were encountered. Thus, Scedosporium can be included as a rare but possible cause of invasive fungal disseminated central nervous system infections in severely neutropenic patients.

Combination treatment of invasive fungal infections

The persistence of high morbidity and mortality from systemic fungal infections despite the availability of novel antifungals points to the need for effective treatment strategies. Treatment of invasive fungal infections is often hampered by drug toxicity, tolerability, and specificity issues, and added complications often arise due to the lack of diagnostic tests and to treatment complexities. Combination therapy has been suggested as a possible approach to improve treatment outcome. In this article, we undertake a historical review of studies of combination therapy and also focus on recent studies involving newly approved antifungal agents. The limitations surrounding antifungal combinations include nonuniform interpretation criteria, inability to predict the likelihood of clinical success, strain variability, and variations in pharmacodynamic/pharmacokinetic properties of antifungals used in combination. The issue of antagonism between polyenes and azoles is beginning to be addressed, but data regarding other drug combinations are not adequate for us to draw definite conclusions. However, recent data have identified potentially useful combinations. Standardization of assay methods and adoption of common interpretive criteria are essential to avoid discrepancies between different in vitro studies. Larger clinical trials are needed to assess whether combination therapy improves survival and treatment outcome in the most seriously debilitated patients afflicted with life-threatening fungal infections.

In vitro activities of voriconazole in combination with three other antifungal agents against Candida glabrata

Candida glabrata has recently emerged as a significant pathogen involved in both superficial and deep-seated infections. In the present study, a checkerboard broth microdilution method was performed to investigate the in vitro activities of voriconazole (VOR) in combination with terbinafine (TRB), amphotericin B (AMB), and flucytosine (5FC) against 20 clinical isolates of C. glabrata. Synergy, defined as a fractional inhibitory concentration (FIC) index of < or = 0.50, was observed in 75% of VOR-TRB, 10% of VOR-AMB, and 5% of VOR-5FC interactions. None of these combinations yielded antagonistic interactions (FIC index > 4). When synergy was not achieved, there was still a decrease in the MIC of one or both drugs used in the combination. In particular, the MICs were reduced to < or = 1.0 microg/ml as a result of the combination for all isolates for which the AMB MIC at the baseline was > or = 2.0 microg/ml. By a disk diffusion assay, the halo diameters produced by antifungal agents in combination were greater that those produced by each drug alone. Finally, killing curves showed that VOR-AMB exhibited synergistic interactions, while VOR-5FC sustained fungicidal activities against C. glabrata. These studies demonstrate that the in vitro activity of VOR against this important yeast pathogen can be enhanced upon combination with other drugs that have different modes of action or that target a different step in the ergosterol pathway. Further studies are warranted to elucidate the potential beneficial effects of such combination regimens in vivo.