Choanephora infundibulifera Rhinosinusitis in Man with Acute Lymphoblastic Leukemia, Tennessee, USA

Choanephora infundibulifera is a member of the Mucorales order of fungi. The species is associated with plants as a saprophyte or parasite and may be responsible for spoilage or disease but is an uncommon cause of human infection. We describe C. infundibulifera rhinosinusitis in a young man with leukemia in Tennessee, USA.

A Mini-Review of In Vitro Data for Candida Species, Including C. auris, Isolated during Clinical Trials of Three New Antifungals: Fosmanogepix, Ibrexafungerp, and Rezafungin

This mini-review summarizes the clinical outcomes and antifungal susceptibility results, where available, for three new antifungals, including fosmanogepix, ibrexafungerp, and rezafungin, against Candida isolates cultured from patients in clinical trials. When reported, most of the data were generated by the Clinical and Laboratory Standards Institute (CLSI) broth microdilution method or by both the CLSI and European Committee on Antimicrobial Susceptibility Testing (EUCAST) methodologies. For fosmanogepix, we summarize the in vitro data for C. auris isolates from 9 patients and for Candida spp. cultured from 20 patients in two clinical trials. Ibrexafungerp has also been evaluated in several clinical trials. From conference proceedings, a total of 176 Candida isolates were evaluated in the FURI and CARES studies, including 18 C. auris isolates (CARES study). However, MIC data are not available for all clinical isolates. Results from the ReSTORE rezafungin phase 3 clinical study also included in vitro results against Candida spp., but no patients with C. auris infections were included. In conclusion, this mini-review summarizes insights regarding clinical outcomes and the in vitro activity of three new antifungals against Candida spp. cultured from patients in clinical trials.

Ibrexafungerp is efficacious in a neutropenic murine model of pulmonary mucormycosis as monotherapy and combined with liposomal amphotericin B

Ibrexafungerp (formerly SCY-078) is the first member of the triterpenoid class that prevents the synthesis of the fungal cell wall polymer β-(1,3)-D-glucan by inhibiting the enzyme glucan synthase. We evaluated the in vivo efficacy of ibrexafungerp against pulmonary mucormycosis using an established murine model. Neutropenic mice were intratracheally infected with either Rhizopus delemar or Mucor circinelloides. Treatment with placebo (diluent control), ibrexafungerp (30 mg/kg, PO BID), liposomal amphotericin B (LAMB 10 mg/kg IV QD), posaconazole (PSC 30 mg/kg PO QD), or a combination of ibrexafungerp plus LAMB or ibrexafungerp plus PSC began 16 h post-infection and continued for 7 days for ibrexafungerp or PSC and through day 4 for LAMB. Ibrexafungerp was as effective as LAMB or PSC in prolonging median survival (range: 15 days to >21 days) and enhancing overall survival (30%-65%) vs placebo (9 days and 0%; P < 0.001) in mice infected with R. delemar. Furthermore, median survival and overall percent survival resulting from the combination of ibrexafungerp plus LAMB were significantly greater compared to all monotherapies (P ≤ 0.03). Similar survival results were observed in mice infected with M. circinelloides. Monotherapies also reduce the lung and brain fungal burden by ~0.5-1.0log10 conidial equivalents (CE)/g of tissue vs placebo in mice infected with R. delemar (P < 0.05), while a combination of ibrexafungerp plus LAMB lowered the fungal burden by ~0.5-1.5log10 CE/g compared to placebo or any of the monotherapy groups (P < 0.03). These results are promising and warrant continued investigation of ibrexafungerp as a novel treatment option against mucormycosis.

Novel antifungals and treatment approaches to tackle resistance and improve outcomes of invasive fungal disease

SUMMARYFungal infections are on the rise, driven by a growing population at risk and climate change. Currently available antifungals include only five classes, and their utility and efficacy in antifungal treatment are limited by one or more of innate or acquired resistance in some fungi, poor penetration into "sequestered" sites, and agent-specific side effect which require frequent patient reassessment and monitoring. Agents with novel mechanisms, favorable pharmacokinetic (PK) profiles including good oral bioavailability, and fungicidal mechanism(s) are urgently needed. Here, we provide a comprehensive review of novel antifungal agents, with both improved known mechanisms of actions and new antifungal classes, currently in clinical development for treating invasive yeast, mold (filamentous fungi), Pneumocystis jirovecii infections, and dimorphic fungi (endemic mycoses). We further focus on inhaled antifungals and the role of immunotherapy in tackling fungal infections, and the specific PK/pharmacodynamic profiles, tissue distributions as well as drug-drug interactions of novel antifungals. Finally, we review antifungal resistance mechanisms, the role of use of antifungal pesticides in agriculture as drivers of drug resistance, and detail detection methods for antifungal resistance.

A Recombinant Multivalent Vaccine (rCpa1) Induces Protection for C57BL/6 and HLA Transgenic Mice against Pulmonary Infection with Both Species of Coccidioides

Coccidioidomycosis is caused by Coccidioides posadasii (Cp) and Coccidioides immitis (Ci), which have a 4-5% difference in their genomic sequences. There is an urgent need to develop a human vaccine against both species. A previously created recombinant antigen (rCpa1) that contains multiple peptides derived from Cp isolate C735 is protective against the autologous isolate. The focus of this study is to evaluate cross-protective efficacy and immune correlates by the rCpa1-based vaccine against both species of Coccidioides. DNA sequence analyses of the homologous genes for the rCpa1 antigen were conducted for 39 and 17 clinical isolates of Cp and Ci, respectively. Protective efficacy and vaccine-induced immunity were evaluated for both C57BL/6 and human HLA-DR4 transgenic mice against five highly virulent isolates of Cp and Ci. There are total of seven amino acid substitutions in the rCpa1 antigen between Cp and Ci. Both C57BL/6 and HLA-DR4 mice that were vaccinated with an rCpa1 vaccine had a significant reduction of fungal burden and increased numbers of IFN-γ- and IL-17-producing CD4+ T cells in the first 2 weeks post challenge. These data suggest that rCpa1 has cross-protection activity against Cp and Ci pulmonary infection through activation of early Th1 and Th17 responses.

Screening the medicine for malaria venture's Pandemic Response Box to identify novel inhibitors of Candida albicans and Candida auris biofilm formation

Candida spp. are opportunistic yeasts capable of forming biofilms, which contribute to resistance, increasing the urgency for new effective antifungal therapies. Repurposing existing drugs could significantly accelerate the development of novel therapies against candidiasis. We screened the Pandemic Response Box containing 400 diverse drug-like molecules active against bacteria, viruses or fungi, for inhibitors of Candida albicans and Candida auris biofilm formation. Initial hits were identified based on the demonstration of >70% inhibitory activity. Dose-response assays were used to confirm the antifungal activity of initial hits and establish their potency. The spectrum of antifungal activity of the leading compounds was determined against a panel of medically important fungi, and the in vivo activity of the leading repositionable agent was evaluated in murine models of C. albicans and C. auris systemic candidiasis. The primary screening identified 20 hit compounds, and their antifungal activity and potency against C. albicans and C. auris were validated using dose-response measurements. From these experiments, the rapalog everolimus, emerged as the leading repositionable candidate. Everolimus displayed potent antifungal activity against different Candida spp., but more moderate levels of activity against filamentous fungi. Treatment with everolimus increased survival of mice infected with C. albicans, but not those with C. auris. The screening of the Pandemic Response Box resulted in the identification of several drugs with novel antifungal activity, with everolimus emerging as the main repositionable candidate. Further in vitro and in vivo studies are needed to confirm its potential therapeutic use.

Tuning sterol extraction kinetics yields a renal-sparing polyene antifungal

Decades of previous efforts to develop renal-sparing polyene antifungals were misguided by the classic membrane permeabilization model1. Recently, the clinically vital but also highly renal-toxic small-molecule natural product amphotericin B was instead found to kill fungi primarily by forming extramembraneous sponge-like aggregates that extract ergosterol from lipid bilayers2-6. Here we show that rapid and selective extraction of fungal ergosterol can yield potent and renal-sparing polyene antifungals. Cholesterol extraction was found to drive the toxicity of amphotericin B to human renal cells. Our examination of high-resolution structures of amphotericin B sponges in sterol-free and sterol-bound states guided us to a promising structural derivative that does not bind cholesterol and is thus renal sparing. This derivative was also less potent because it extracts ergosterol more slowly. Selective acceleration of ergosterol extraction with a second structural modification yielded a new polyene, AM-2-19, that is renal sparing in mice and primary human renal cells, potent against hundreds of pathogenic fungal strains, resistance evasive following serial passage in vitro and highly efficacious in animal models of invasive fungal infections. Thus, rational tuning of the dynamics of interactions between small molecules may lead to better treatments for fungal infections that still kill millions of people annually7,8 and potentially other resistance-evasive antimicrobials, including those that have recently been shown to operate through supramolecular structures that target specific lipids9.

Coccidioides species antifungal susceptibility testing: Experience from a large healthcare system in the endemic region

The clinical utility of Coccidioides species antifungal susceptibility testing (AST) remains unclear. This study describes the clinical course of eight patients with severe or chronic coccidioidomycosis and subsequent Coccidioides AST. We present the clinical manifestations, antifungal treatment regimens, and clinical outcomes for these patients.

Utility of triazole antifungal therapeutic drug monitoring: Insights from the Society of Infectious Diseases Pharmacists: Endorsed by the Mycoses Study Group Education and Research Consortium

Triazole antifungals (i.e., fluconazole, itraconazole, voriconazole, posaconazole, and isavuconazole) are commonly used in clinical practice to prevent or treat invasive fungal infections. Most triazole antifungals require therapeutic drug monitoring (TDM) due to highly variable pharmacokinetics, known drug interactions, and established relationships between exposure and response. On behalf of the Society of Infectious Diseases Pharmacists (SIDP), this insight describes the pharmacokinetic principles and pharmacodynamic targets of commonly used triazole antifungals and provides the rationale for utility of TDM within each agent.

Update on Outbreak of Fungal Meningitis among U.S. Residents who Received Epidural Anesthesia at Two Clinics in Matamoros, Mexico

BACKGROUND

Public health officials are responding to an outbreak of fungal meningitis among patients who received procedures under epidural anesthesia at two clinics (River Side Surgical Center and Clinica K-3) in Matamoros, Mexico, during January 1-May 13, 2023. This report describes outbreak epidemiology and outlines interim diagnostic and treatment recommendations.

METHODS

Interim recommendations for diagnosis and management were developed by the Mycoses Study Group Research Education and Consortium (MSGERC) based on the clinical experience of clinicians caring for patients during the current outbreak or during previous outbreaks of healthcare-associated fungal meningitis in Durango, Mexico, and the United States.

RESULTS

As of July 7, 2023, the situation has evolved into a multistate and multinational fungal meningitis outbreak. A total of 185 residents in 22 U.S. states and jurisdictions have been identified who might be at risk of fungal meningitis because they received epidural anesthesia at the clinics of interest in 2023. Among these patients, 11 suspected, 10 probable, and 10 confirmed U.S. cases have been diagnosed, with severe vascular complications and eight deaths occurring. Fusarium solani species complex has been identified as the causative agent, with antifungal susceptibility testing of a single isolate demonstrating poor in vitro activity for most available antifungals. Currently, triple therapy with intravenous voriconazole, liposomal amphotericin B, and fosmanogepix is recommended.

CONCLUSIONS

Efforts to understand the source of this outbreak and optimal treatment approaches are ongoing, but infectious diseases physicians should be aware of available treatment recommendations. New information will be available on CDC's website.

Kneiffiella palmae: A non-Aspergillus fungal infection isolated from a pulmonary nodule in a child with chronic granulomatous disease

We report the first known human case of Kneiffiella palmae in the medical literature. K. palmae was isolated from a pulmonary nodule in a 7-year-old male with chronic granulomatous disease. The mold was identified as K. palmae at a national reference laboratory, where 17 other human respiratory samples tested positive for K. palmae from 2013 to 2021. Optimal antimicrobial treatment is unknown, but azoles and amphotericin B demonstrated in vitro activity against each tested isolate.

High-Throughput Screening of the Repurposing Hub Library to Identify Drugs with Novel Inhibitory Activity against Candida albicans and Candida auris Biofilms

Candidiasis is one of the most frequent nosocomial infections affecting an increasing number of at-risk patients. Candida albicans remains the most frequent causative agent of candidiasis, but, in the last decade, C. auris has emerged as a formidable multi-drug-resistant pathogen. Both species are fully capable of forming biofilms, which contribute to resistance, increasing the urgency for new effective antifungal therapies. Repurposing existing drugs could significantly accelerate the development of novel therapies against candidiasis. Here, we have screened the Repurposing Hub library from the Broad Institute, containing over 6000 compounds, in search for inhibitors of C. albicans and C. auris biofilm formation. The primary screen identified 57 initial hits against C. albicans and 33 against C. auris. Confirmatory concentration-dependent assays were used to validate the activity of the initial hits and, at the same time, establish their anti-biofilm potency. Based on these results, ebselen, temsirolimus, and compound BAY 11-7082 emerged as the leading repositionable compounds. Subsequent experiments established their spectrum of antifungal activity against yeasts and filamentous fungi. In addition, their in vivo activity was examined in the murine models of hematogenously disseminated C. albicans and C. auris infections. Although promising, further in vitro and in vivo studies are needed to confirm their potential use for the therapy of candidiasis and possibly other fungal infections.

Terbinafine-Resistant Dermatophytes and the Presence of Trichophyton indotineae in North America

Dermatophytes are common causes of skin, hair, and nail infections in humans. The most common species causing infections in humans are Trichophyton rubrum, Trichophyton mentagrophytes, and Trichophyton interdigitale. Outbreaks of recalcitrant dermatophytosis have been reported in parts of South Asia, including those caused by a hypervirulent and resistant species, Trichophyton indotineae. We evaluated the antifungal susceptibility profiles of dermatophytes received by our laboratory from institutions across North America between 2021 and 2022 and performed species identification for isolates deemed to demonstrate in vitro resistance. Susceptibility testing was performed by CLSI broth microdilution methods, and species identification was performed by DNA sequence analysis. During this 2-year period, 271 dermatophyte isolates were included, the majority of which demonstrated low MIC values for terbinafine (geometric mean [GM] and modal MIC, 0.031 μg/mL and 0.008 μg/mL, respectively) and the azoles itraconazole, posaconazole, and voriconazole (0.035 to 0.049 μg/mL and ≤0.03 μg/mL). However, 18.6% of the isolates tested were resistant to terbinafine (MIC ≥ 0.5 μg/mL), including 21 T. rubrum and 21 T. indotineae isolates. These isolates were received from several different states in the United States and two provinces in Canada. In contrast, resistance to itraconazole was relatively rare. We also searched our laboratory database for earlier isolates that were resistant to terbinafine and identified 3 additional T. indotineae isolates, the earliest of which was from 2017. These results demonstrate that terbinafine resistance in dermatophytes was relatively common over this 2-year period and that T. indotineae is present in multiple areas in North America. Continued surveillance is warranted.

Low Rates of Antifungal Therapeutic Drug Monitoring Among Inpatients Who Received Itraconazole, Posaconazole, or Voriconazole, United States, 2019-2021

Antifungal therapeutic drug monitoring (TDM) is recommended for hospitalized patients receiving itraconazole, posaconazole, or voriconazole for treatment or prophylaxis. In this analysis of hospital-based data, TDM was uncommonly performed (15.8%) in a large cohort of eligible patients, suggesting missed opportunities to avoid subtherapeutic drug levels and minimize toxicity.

hapE and hmg1 Mutations Are Drivers of cyp51A-Independent Pan-Triazole Resistance in an Aspergillus fumigatus Clinical Isolate

Aspergillus fumigatus is a ubiquitous environmental mold that can cause severe disease in immunocompromised patients and chronic disease in individuals with underlying lung conditions. Triazoles are the most widely used class of antifungal drugs to treat A. fumigatus infections, but their use in the clinic is threatened by the emergence of triazole-resistant isolates worldwide, reinforcing the need for a better understanding of resistance mechanisms. The predominant mechanisms of A. fumigatus triazole resistance involve mutations affecting the promoter region or coding sequence of the target enzyme of the triazoles, Cyp51A. However, triazole-resistant isolates without cyp51A-associated mutations are frequently identified. In this study, we investigate a pan-triazole-resistant clinical isolate, DI15-105, that simultaneously carries the mutations hapEP88L and hmg1F262del, with no mutations in cyp51A. Using a Cas9-mediated gene-editing system, hapEP88L and hmg1F262del mutations were reverted in DI15-105. Here, we show that the combination of these mutations accounts for pan-triazole resistance in DI15-105. To our knowledge, DI15-105 is the first clinical isolate reported to simultaneously carry mutations in hapE and hmg1 and only the second with the hapEP88L mutation. IMPORTANCE Triazole resistance is an important cause of treatment failure and high mortality rates for A. fumigatus human infections. Although Cyp51A-associated mutations are frequently identified as the cause of A. fumigatus triazole resistance, they do not explain the resistance phenotypes for several isolates. In this study, we demonstrate that hapE and hmg1 mutations additively contribute to pan-triazole resistance in an A. fumigatus clinical isolate lacking cyp51-associated mutations. Our results exemplify the importance of and the need for a better understanding of cyp51A-independent triazole resistance mechanisms.

Systemic Exophiala equina infection in an Eastern box turtle (Terrapene carolina carolina): a case report and literature review

Phaeohyphomycosis is an infection caused by melanized fungi. This disease has been reported in several animal species including invertebrates, cold-blooded vertebrates, mammals, and humans. Melanized fungi have similar phenotypical features and confirmation requires culture and molecular diagnostics. To exemplify this we present a case of a 333 g adult of unknown age, free-ranging, male Eastern box turtle (Terrapene carolina carolina) that was referred to the Turtle Rescue Team at North Carolina State University for evaluation of multilobulated masses occupying the entire left orbit and at the right forelimb on the plantarolateral aspect of the foot. A fine needle aspirate cytologic examination of the mass on the right forelimb revealed large numbers of inflammatory cells and fungal organisms. Histopathology of the skin biopsies from the right forefoot was consistent with phaeohyphomycosis. A course of antifungal medication was started (Fluconazole 21 mg/kg loading dose IV then 5 mg/kg PO SID q 30 days). Due to concern for the patient's quality of life and the lack of a curative treatment plan, humane euthanasia was elected. Gross and histological postmortem examination confirmed the presence of multiple coelomic masses similar in appearance to those observed in the left orbit and right forefoot indicating disseminated phaeohyphomycosis. A swab of the periocular mass was submitted for fungal culture and phenotypic identification. The isolate was later identified as Exophiala equina through a combination of phenotypic characterization and sequencing of the ITS region of the nuclear rDNA. Exophiala is a genus in the family Herpotrichiellaceae, order Chaetothyriales and is considered an opportunistic "black yeast" causing infection in aquatic invertebrates, fish, amphibians, reptiles, and mammals including humans. Exophiala equina is infrequently reported in animals, with only three cases in the literature including the herein report.

Species Distribution and Antifungal Susceptibilities of Aspergillus Section Terrei Isolates in Clinical Samples from the United States and Description of Aspergillus pseudoalabamensis sp. nov

Aspergillus section Terrei consists of numerous cryptic species in addition to A. terreus sensu stricto. The treatment of invasive infections caused by these fungi may pose a unique challenge prior to diagnosis and species identification, in that they are often clinically resistant to amphotericin B, with poor outcomes and low survival rates in patients treated with this polyene. Data on the species distributions and susceptibility profiles of isolates within section Terrei from the United States (U.S.) are limited. Here, we report the species distributions and susceptibility profiles for amphotericin B, isavuconazole, itraconazole, posaconazole, voriconazole, and micafungin against 278 clinical isolates of this section from institutions across the U.S. collected over a 52-month period. Species identification was performed by DNA sequence analysis and phenotypic characterization. Susceptibility testing was performed using the CLSI broth microdilution method. The majority of isolates were identified as Aspergillus terreus sensu stricto (69.8%), although several other cryptic species were also identified. Most were cultured from specimens collected from the respiratory tract. Posaconazole demonstrated the most potent activity of the azoles (MIC range ≤ 0.03-1 mg/L), followed by itraconazole (≤0.03-2 mg/L), voriconazole, and isavuconazole (0.125-8 mg/L for each). Amphotericin B demonstrated reduced in vitro susceptibility against this section (MIC range 0.25-8 mg/L), although this appeared to be species-dependent. A new species within this section, A. pseudoalabamensis, is also described. Our results, which are specific to the U.S., are similar to previous surveillance studies of the Aspergillus section Terrei.

Dihydroorotate dehydrogenase inhibitor olorofim has potent in vitro activity against Microascus/Scopulariopsis, Rasamsonia, Penicillium and Talaromyces species

BACKGROUND

Treatment options against infections caused by rare but emerging moulds may be limited by their reduced susceptibility or resistance to clinically available antifungals. The investigational antifungal olorofim, which targets the biosynthesis of pyrimidines within fungi, has activity against different species of filamentous fungi, including Aspergillus and Scedosporium/Lomentospora prolificans isolates that are resistant to available antifungals.

OBJECTIVE

We evaluated the in vitro activity of olorofim against 160 isolates within the genera Microascus/Scopulariopsis, Penicillium, Talaromyces and the Rasamsonia argillacea species complex.

METHODS

One hundred sixty clinical isolates that had previously been identified to the species level by DNA sequence analysis were included. Antifungal susceptibility testing was performed by CLSI M38 broth microdilution for olorofim, amphotericin B, caspofungin, posaconazole and voriconazole.

RESULTS

Olorofim demonstrated in vitro activity against each of the genera tested. Overall, olorofim MICs ranged from ≤0.008 to 0.5 mg/L against all isolates tested, with MIC₉₀ and modal MIC values ranging from ≤0.008 to 0.25 mg/L and ≤0.008 to 0.03 mg/L, respectively. This activity was also maintained against individual isolates that had reduced susceptibility to or in vitro resistance against amphotericin B, posaconazole and/or voriconazole.

CONCLUSIONS

The investigational agent olorofim demonstrated good in vitro activity against clinical isolates of emerging mould pathogens, including those with reduced susceptibility or resistance to clinically available antifungals. Further studies are warranted to determine how well this in vitro activity translates into in vivo efficacy against infections caused by these fungi.

Fungal keratitis caused by Coniochaeta mutabilis – a case report

We present a rare case of recalcitrant fungal keratitis caused by Coniochaeta mutabilis, successfully managed with a course of oral, topical, intrastromal, and intracameral antifungals. A 57-year-old male on their fourth week of treatment for presumed left herpes simplex keratitis presented to clinic with severe left-sided foreign body sensation after gardening in his yard. On examination, a white corneal plaque was observed at 8 o'clock, shown to be a dense collection of fungal hyphae on confocal microscopy. Corneal cultures revealed yeast-like cells, initially identified as Kabatiella zeae by matching 100% identity with K. zeae strains CBS 767.71 and CBS 265.32 in BLASTn search using the internal transcribed spacer (ITS) sequence. Treated for over four months with topical amphotericin B and oral voriconazole without improvement, recourse to intrastromal and intracameral amphotericin B injections, coupled with the application of cyanoacrylate glue to the lesion and a bandage contact lens, led to eventual resolution. The patient subsequently underwent cataract surgery, achieving a BCVA of 20/20 in the eye. Surprisingly, upon further sequence analyses of combined ITS and large subunit ribosomal ribonucleic acid (LSU) and investigation of the K. zeae German strain CBS 767.71, the organism was revealed to be Coniochaeta mutabilis (formerly Lecythospora mutabilis). This means that the correct name for CBS 767.71 and CBS 265.32 is C. mutabilis and should be corrected in the GenBank record to avoid misleading identification in the future. This case also underscores the urgent unmet need for improved molecular diagnostic modalities in the care of corneal infections.

Antifungal Susceptibility of Yeasts and Filamentous Fungi by CLSI Broth Microdilution Testing

Antifungal susceptibility testing is performed against yeasts and filamentous fungi (molds) for various purposes. In clinical settings, the results of these in vitro assays may be used to help guide therapy for individual patients. Surveillance studies use susceptibility testing to monitor for the development of resistance to different agents. These assays are also frequently used in preclinical drug development to determine the spectrum of activity and assess the in vitro potency of investigational agents. Broth microdilution is a form of antifungal susceptibility testing that is frequently used for each of these purposes. The Clinical and Laboratory Standards Institute (CLSI) has developed standardized methods for broth microdilution antifungal susceptibility testing of both yeasts and molds. These methods are useful in the clinical diagnostics arena for determining if a particular fungal isolate may be resistant to clinically available antifungals, and they are also amendable for research purposes, as the microtiter trays can be prepared in different formats with different antifungal and investigational agent concentration ranges and with different growth media if necessary. This chapter describes the CLSI methods for antifungal susceptibility testing by broth microdilution for both yeasts and molds, how endpoints are read for different classes of antifungal agents, and how the results may be interpreted.

Hidden in plain sight: urinary Cryptococcus neoformans missed by routine diagnostics in a patient with acute leukemia

Cryptococcuria is a rare manifestation of localized cryptococcal disease. We present a case of Cryptococcus neoformans urinary tract infection in an immunocompromised host missed by routine laboratory workup. The patient had negative blood cultures, a negative serum cryptococcal antigen (CrAg), and “non-Candida yeast” growing in urine culture that was initially dismissed as non-pathogenic. The diagnosis was ultimately made by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) from a repeat urine culture after transfer to a tertiary care center. Cryptococcus should be considered in the differential of refractory urinary tract infections growing non-Candida yeast.

Pharmacodynamics, Mechanisms of Action and Resistance, and Spectrum of Activity of New Antifungal Agents

Several new antifungals are currently in late-stage development, including those with novel pharmacodynamics/mechanisms of action that represent new antifungal classes (manogepix, olorofim, ATI-2307, GR-2397). Others include new agents within established classes or with mechanisms of action similar to clinically available antifungals (ibrexafungerp, rezafungin, oteseconazole, opelconazole, MAT2203) that have been modified in order to improve certain characteristics, including enhanced pharmacokinetics and greater specificity for fungal targets. Many of the antifungals under development also have activity against Candida and Aspergillus strains that have reduced susceptibility or acquired resistance to azoles and echinocandins, whereas others demonstrate activity against species that are intrinsically resistant to most clinically available antifungals. The tolerability and drug–drug interaction profiles of these new agents also appear to be promising, although the number of human subjects that have been exposed to many of these agents remains relatively small. Overall, these agents have the potential for expanding our antifungal armamentarium and improving clinical outcomes in patients with invasive mycoses.

Invasive candidiasis: Investigational drugs in the clinical development pipeline and mechanisms of action

INTRODUCTION

The epidemiology of invasive Candida infections is evolving. Infections caused by non-albicans Candida spp. are increasing; however, the antifungal pipeline is more promising than ever and is enriched with repurposed drugs and agents that have new mechanisms of action. Despite progress, unmet needs in the treatment of invasive candidiasis remain and there are still too few antifungals that can be administered orally or that have CNS penetration.

AREAS COVERED

The authors shed light on those antifungal agents active against Candida that are in late-stage clinical development. Mechanisms of action and key pharmacokinetic and pharmacodynamic properties are discussed. Insights are offered on the potential future roles of the investigational agents MAT-2203, oteseconazole, ATI-2307, VL-2397, NP-339, and the repurposed drug miltefosine.

EXPERT OPINION

Ibrexafungerp and fosmanogepix have novel mechanisms of action and will provide effective options for the treatment of Candida infections (including those caused by multiresistant Candida spp). Rezafungin, an echinocandin with an extended half-life allowing for once weekly administration, will be particularly valuable for outpatient treatment and prophylaxis. Despite this, there is an urgent need to garner clinical data on investigational drugs, especially in the current rise of azole-resistant and multi-drug resistant Candida spp.

Rigidoporus corticola Colonization and Invasive Fungal Disease in Immunocompromised Patients, United States

We report 2 cases of Rigidoporus corticola (Oxyporus corticola) infection in humans in the United States. Clinical manifestations consisted of angioinvasive fungal sinusitis in 1 patient and pulmonary intracavitary fungus ball in the other patient. These cases illustrate previously undescribed clinicopathologic manifestations of infection by this filamentous basidiomycete in humans.

Emerging Fungal Infections: New Species, New Names, and Antifungal Resistance

Background

Infections caused by fungi can be important causes of morbidity and mortality in certain patient populations, including those who are highly immunocompromised or critically ill. Invasive mycoses can be caused by well-known species, as well as emerging pathogens, including those that are resistant to clinically available antifungals.

Content

This review highlights emerging fungal infections, including newly described species, such as Candida auris, and those that having undergone taxonomic classification and were previously known by other names, including Blastomyces and Emergomyces species, members of the Rasamsonia argillacea species complex, Sporothrix brasiliensis, and Trichophyton indotinae. Antifungal resistance also is highlighted in several of these emerging species, as well as in the well-known opportunistic pathogen Aspergillus fumigatus. Finally, the increased recognition and importance of fungal co-infections with respiratory pathogens, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is discussed.

Summary

Both clinicians and clinical microbiology laboratories should remain vigilant regarding emerging fungal infections. These may be difficult both to diagnose and treat due to the lack of experience of clinicians and laboratory personnel with these organisms and the infections they may cause. Many of these fungal infections have been associated with poor clinical outcomes, either due to inappropriate therapy or the development of antifungal resistance.

Antifungal Susceptibility Testing: A Primer for Clinicians

Clinicians treating patients with fungal infections may turn to susceptibility testing to obtain information regarding the activity of different antifungals against a specific fungus that has been cultured. These results may then be used to make decisions regarding a patient's therapy. However, for many fungal species that are capable of causing invasive infections, clinical breakpoints have not been established. Thus, interpretations of susceptible or resistant cannot be provided by clinical laboratories, and this is especially true for many molds capable of causing severe mycoses. The purpose of this review is to provide an overview of susceptibility testing for clinicians, including the methods used to perform these assays, their limitations, how clinical breakpoints are established, and how the results may be put into context in the absence of interpretive criteria. Examples of when susceptibility testing is not warranted are also provided.

Retrospective study of phaeohyphomycosis in aquarium-housed fish, with first descriptions of Exophiala lecanii-corni and Neodevriesia cladophorae in fish

A broadening fish host range is affected by novel and known pigmented fungal pathogens. A review of 2,250 piscine submissions received by the Aquatic Pathology Service, University of Georgia, revealed 47 phaeohyphomycosis cases (2.1%), representing 34 bony and cartilaginous fish species. The majority involved bony fish (45/47, 95.7%) and were predominantly marine (41/47, 87.2%), with only a few freshwater species (4/47, 8.5%). Cartilaginous fish cases included two zebra sharks (Stegostoma fasciatum) (2/47, 4.3%). Northern seahorses (Hippocampus erectus) had the highest incidence overall (7/47, 14.9%). Culture and sequencing of the internal-transcribed spacer region of the rDNA (ITS), large ribosomal subunit gene D1/D2 domains (LSU) and the DNA polymerase II gene (RPB2) were performed for fungal identification when fresh tissue was obtainable. Exophiala, Ochroconis and Neodevriesia spp. were identified, with Exophiala as the most common fungal genus (8/11, 72.7%). Exophiala lecanii-corni and Neodevriesia cladophorae were described for the first time from fish. Microscopically, lesions were characterized by necrosis, granulomatous inflammation and angioinvasion most frequently affecting the skin/fin, skeletal muscle and kidneys. In this study of diverse aquarium-housed fish species, phaeohyphomycosis cases occurred sporadically and in rare outbreaks with variable pathologic presentations, tissue distributions and severities.

The Promise of Lung Organoids for Growth and Investigation of Pneumocystis Species

Pneumocystis species (spp.) are host-obligate fungal parasites that colonize and propagate almost exclusively in the alveolar lumen within the lungs of mammals where they can cause a lethal pneumonia. The emergence of this pneumonia in non-HIV infected persons caused by Pneumocystis jirovecii (PjP), illustrates the continued importance of and the need to understand its associated pathologies and to develop new therapies and preventative strategies. In the proposed life cycle, Pneumocystis spp. attach to alveolar type 1 epithelial cells (AEC1) and prevent gas exchange. This process among other mechanisms of Pneumocystis spp. pathogenesis is challenging to observe in real time due to the absence of a continuous ex vivo or in vitro culture system. The study presented here provides a proof-of-concept for the development of murine lung organoids that mimic the lung alveolar sacs expressing alveolar epithelial type 1 cells (AEC1) and alveolar type 2 epithelial cells (AEC2). Use of these 3-dimensional organoids should facilitate studies of a multitude of unanswered questions and serve as an improved means to screen new anti- PjP agents.

Epidemiology and Antifungal Susceptibilities of Mucoralean Fungi in Clinical Samples from the United States

The global incidence of mucormycosis has increased in recent years owing to higher numbers of individuals at risk for these infections. The diagnosis and treatment of this aggressive fungal infection are of clinical concern due to differences in species distribution in different geographic areas and susceptibility profiles between different species that are capable of causing highly aggressive infections. The purpose of this study was to evaluate the epidemiology and susceptibility profiles of Mucorales isolates in the United States over a 52-month period. Species identification was performed by combined phenotypic characteristics and DNA sequence analysis, and antifungal susceptibility testing was performed by CLSI M38 broth microdilution for amphotericin B, isavuconazole, itraconazole, and posaconazole. During this time frame, 854 isolates were included, representing 11 different genera and over 26 species, of which Rhizopus (58.6%) was the predominant genus, followed by Mucor (19.6%). The majority of isolates were cultured from the upper and lower respiratory tracts (55%). Amphotericin B demonstrated the most potent in vitro activity, with geometric mean (GM) MICs of ≤0.25 μg/ml against all genera with the exception of Cunninghamella species (GM MIC of 1.30 μg/ml). In head-to-head comparisons, the most active azole was posaconazole, followed by isavuconazole. Differences in azole and amphotericin B susceptibility patterns were observed between the genera with the greatest variability observed with isavuconazole. Awareness of the epidemiology of Mucorales isolates and differences in antifungal susceptibility patterns in the United States may aide clinicians in choosing antifungal treatment regimens. Further studies are warranted to correlate these findings with clinical outcomes.

Phylogenomic Analysis of a 55.1-kb 19-Gene Dataset Resolves a Monophyletic Fusarium that Includes the Fusarium solani Species Complex

Scientific communication is facilitated by a data-driven, scientifically sound taxonomy that considers the end-user's needs and established successful practice. In 2013, the Fusarium community voiced near unanimous support for a concept of Fusarium that represented a clade comprising all agriculturally and clinically important Fusarium species, including the F. solani species complex (FSSC). Subsequently, this concept was challenged in 2015 by one research group who proposed dividing the genus Fusarium into seven genera, including the FSSC described as members of the genus Neocosmospora, with subsequent justification in 2018 based on claims that the 2013 concept of Fusarium is polyphyletic. Here, we test this claim and provide a phylogeny based on exonic nucleotide sequences of 19 orthologous protein-coding genes that strongly support the monophyly of Fusarium including the FSSC. We reassert the practical and scientific argument in support of a genus Fusarium that includes the FSSC and several other basal lineages, consistent with the longstanding use of this name among plant pathologists, medical mycologists, quarantine officials, regulatory agencies, students, and researchers with a stake in its taxonomy. In recognition of this monophyly, 40 species described as genus Neocosmospora were recombined in genus Fusarium, and nine others were renamed Fusarium. Here the global Fusarium community voices strong support for the inclusion of the FSSC in Fusarium, as it remains the best scientific, nomenclatural, and practical taxonomic option available.

Novel Penicillium species causing disseminated disease in a Labrador Retriever dog

This report describes the phenotypic characteristics of a novel Penicillium species, Penicillium labradorum, isolated from a 3-year-old male, castrated, Labrador retriever with disseminated fungal disease. The dog's presenting clinical signs included lethargy, lymphadenopathy, tachypnea, moderate pitting edema, and nonweight bearing lameness associated with the right hind limb. Fine-needle aspirate biopsies from the sublumbar and prescapular lymph nodes were initially examined. The cytologic findings were consistent with pyogranulomatous inflammation with abundant extracellular and phagocytized fungal fragments and hyphae. Based on the morphology of the organisms and lack of endogenous pigment, hyalohyphomycosis was considered most likely, with Fusarium, Penicillium, and Paecilomyces species being considerations. Fungal isolates were obtained via culture of samples from the lymph nodes, and molecular identification testing originally identified an undescribed Penicillium species belonging to the Penicillium section Exilicaulis. BLAST searches and phylogenetic analyses performed approximately 1 year and 9 months after the isolation date revealed an isolate within the Penicillium parvum clade in the Penicillium section Exilicaulis but phylogenetically distant from the other species in the section, thus representing a new species, Penicillium labradorum. Antifungal susceptibility testing was also performed on the isolate and low minimum inhibitory concentrations were observed with terbinafine, voriconazole, and posaconazole, while in vitro resistance was observed with fluconazole. The dog had been previously treated with fluconazole, itraconazole, amphotericin B lipid complex, voriconazole, and terbinafine. Approximately 587 days after the initial diagnosis, the dog was euthanized due to worsening of clinical signs and concerns for quality of life.

Pseudocanariomyces americanus, gen. nov., sp. nov., A New Thielavia-Like Species in the Chaetomiaceae: Identification and Management of a Prosthetic Hip Infection

This report describes the phenotypic characteristics of a novel fungal species, isolated from a prosthetic hip infection. The patient, who had undergone multiple total hip arthroplasties due to Legg-Calvé-Perthes disease, presented with continued fever and wound dehiscence. Findings upon incision and draining were notable for necrotic tissue and a sinus tract from the fluid collection. Intraoperative cultures were positive for a sterile filamentous fungus. BLASTn results following DNA sequencing placed the isolate within the family Chaetomiaceae close to the genera Madurella, Canariomyces, Stolonocarpus, Stellatospora, Ovatospora, Carteria and Melanocarpus. Phylogenetic analysis demonstrated that the isolate was a new thielavia-like species, Pseudocanariomyces americanus. Antifungal susceptibility was performed, and low minimum inhibitory concentrations were observed with amphotericin B, itraconazole, posaconazole, and voriconazole. The patient was initially treated with voriconazole but was switched to posaconazole secondary to a photosensitivity reaction. Acceptable posaconazole trough concentrations were achieved, and the patient remained stable without pain or drainage from her surgical incision.

Evaluation of Sex Differences in Murine Diabetic Ketoacidosis and Neutropenic Models of Invasive Mucormycosis

There is increased concern that the quality, generalizability and reproducibility of biomedical research can be influenced by the sex of animals used. We studied the differences between male and female mice in response to invasive pulmonary mucormycosis including susceptibility to infection, host immune reaction and responses to antifungal therapy. We used diabetic ketoacidotic (DKA) or neutropenic mice infected with either Rhizopus delemar or Mucor circinelloides. The only difference detected was that when DKA mice were infected with M. circinelloides, female mice were more resistant to infection than male mice (median survival time of 5 vs. 2 days for female and male mice, respectively). However, a 100% lethality was detected among infected animals of both sexes. Treatment with either liposomal amphotericin B (L-AMB) or posaconazole (POSA) protected mice from infection and eliminated the difference seen between infected but untreated female and male mice. Treatment with L-AMB consistently outperformed POSA in prolonging survival and reducing tissue fungal burden of DKA and neutropenic mice infected with R. delemar or M. circinelloides, in both mouse sexes. While little difference was detected in cytokine levels among both sexes, mucormycosis infection in the DKA mouse model induced more inflammatory cytokines/chemokines involved in neutrophil (CXCL1) and macrophage (CXCL2) recruitment vs. uninfected mice. As expected, this inflammatory response was reduced in the neutropenic mouse model. Our studies show that there are few differences between female and male DKA or neutropenic mice infected with mucormycosis with no effect on the outcome of treatment or host immune response.

In vitro activity of olorofim against clinical isolates of the Fusarium oxysporum and Fusarium solani species complexes

BACKGROUND

Invasive fusariosis is associated with marked morbidity and mortality in immunocompromised hosts, and clinical outcomes are poor with conventional therapy. Olorofim (F901318) is an investigational antifungal in the orotomide class that selectively targets fungal dihydroorotate dehydrogenase (DHODH) causing inhibition of pyrimidine biosynthesis.

OBJECTIVE

We evaluated the in vitro activity of olorofim against 61 clinical isolates of the Fusarium oxysporum and F solani species complexes (FOSC and FSSC, respectively), the most prevalent causes of invasive fusariosis.

METHODS

Clinical isolates of FOSC (n = 45) and FSSC (n = 16) were identified using DNA sequence analysis of the translation elongation factor 1-alpha (TEF1α) and RNA polymerase II second largest subunit (RPB2). Antifungal susceptibility testing was performed by CLSI M38 broth microdilution for olorofim, amphotericin B, isavuconazole, posaconazole, voriconazole and micafungin.

RESULTS

Olorofim demonstrated good in vitro activity against both FOSC and FSSC. Against the 45 FOSC isolates, olorofim MICs ranged between 0.03-0.5 mg/L and 0.06->4 mg/L at the 50% and 100% inhibition endpoints, respectively. Against FSSC isolates, olorofim MIC ranged between 0.25-1 mg/L and 1->4 mg/L at 50% and 100% inhibition, respectively. While amphotericin B also demonstrated similar in vitro activity (MIC ranges 1-4 and 0.25-4 mg/L against FOSC and FSSC, respectively), neither the triazoles nor micafungin demonstrated consistent in vitro activity against Fusarium isolates at clinically relevant concentrations.

CONCLUSIONS

The investigational agent olorofim demonstrated good in vitro activity against FOSC and FSSC clinical isolates. Further studies are warranted to determine how well this in vitro activity translates into in vivo efficacy.

Pulmonary infection secondary to Blastobotrys raffinosifermentans in a cystic fibrosis patient: Review of the literature

BACKGROUND

The genus Blastobotrys consists of at least 20 species. Disease in humans has been reported with B adeninivorans, B raffinosifermentans, B proliferans and B serpentis, mostly in immunocompromised patients and those with cystic fibrosis.

OBJECTIVE

We report a lung infection secondary to B raffinosifermentans in a cystic fibrosis patient successfully treated with isavuconazole and review the literature of invasive infections caused this genus. We also evaluated clinical isolates in our laboratory for species identification and antifungal susceptibility.

METHODS

Phylogenetic analysis was performed on a collection of 22 Blastobotrys isolates in our reference laboratory, and antifungal susceptibility patterns were determined for nine clinically available antifungals against 19 of these isolates.

RESULTS

By phylogenetic analysis, 21 of the 22 isolates in our collection were identified as B raffinosifermentans and only 1 as B adeninivorans. Most were cultured from the respiratory tract, although others were recovered from other sources, including CSF and blood. Isavuconazole, caspofungin and micafungin demonstrated the most potent in vitro activity, followed by amphotericin B. In contrast, fluconazole demonstrated poor activity. The patient in this case responded to isavuconazole treatment for breakthrough infection due to B raffinosifermentans that was cultured from pleural fluid while on posaconazole prophylaxis post-bilateral lung transplantation for cystic fibrosis.

CONCLUSIONS

Blastobotrys species are rare causes of infections in humans and primarily occur in immunocompromised hosts. In our collection, the majority of isolates were identified as B raffinosifermentans. To our knowledge, this is the first report of successful treatment of such an infection with isavuconazole.

Case Report: Successful Management of Conidiobolus Lamprauges Rhinitis in a Dog

This is a case of Conidiobolus lamprauges rhinitis in a Goldendoodle, that was presented for evaluation of sneezing, coughing, lethargy, as well as right-sided epistaxis and clear ocular discharge. Computed tomography revealed a large amount of soft tissue within the right nasal passage that obscured the osseous turbinates from the right maxillary canine tooth to the right side of the choanae. Biopsies revealed eosinophilic granulomas with variable number of basophilic to negatively staining, septate, fungal hyphae with non-parallel walls and irregular branching that were subsequently determined to be Conidiobolus lamprauges via panfungal PCR and sequencing. Complete and sustained resolution of clinical disease was achieved after 75 days of systemic antifungal therapy. This report describes for the first time, important clinical features of a dog with nasal conidiobolomycosis that will facilitate its recognition, prognostication, and treatment in clinical practice.

1282. Manogepix, the Active Moiety of the Investigational Agent Fosmanogepix, Demonstrates In vitro Activity Against Members of the Fusarium oxysporum and Fusarium solani Species Complexes

Background

Invasive fusariosis is associated with marked morbidity and mortality in immunocompromised hosts, and treatment options are limited. Common etiologic agents include members of the F. oxysporum and F. solani species complexes (FOSC and FSSC, respectively). Manogepix (MGX), the active moiety of fosmanogepix, is a novel GWT1 inhibitor with broad antifungal activity. Fosmanogepix has previously shown in vivo efficacy in an immunocompromised murine model of invasive fusariosis. Our objective was to evaluate the in vitro activity of MGX against FOSC and FSSC isolates.

Methods

Clinical isolates of FOSC (n=49) and FSSC (19) were identified by combined phenotypic characteristics and DNA sequence analysis of the translation elongation factor 1-alpha (TEF1α) and RNA polymerase II second largest subunit (RPB2). Antifungal susceptibility testing was performed by CLSI M38 broth microdilution. Minimum effective concentrations (MEC) and minimum inhibitory concentrations (MIC) were read after 48 hours of incubation at 50% and 100% inhibition of growth for MGX, and MIC values were read for amphotericin B, posaconazole, isavuconazole, and voriconazole at 100% inhibition of growth.

Results

MGX demonstrated potent in vitro activity against both FOSC and FSSC isolates. Against the 49 FOSC isolates, the MGX MECs ranged from &lt;0.015-0.03 mg/mL, and MICs at the 50% inhibition of growth endpoint ranged from &lt;0.015-0.12 mg/mL (Table). MIC values were higher when read at 100% inhibition of growth. Similar results were observed against FSSC isolates (MEC and MIC ranges &lt;0.015 and &lt;0.015-0.25 mg/mL, respectively). MGX MEC and MIC 50% inhibition values were in close agreement for both FOSC and FSSC isolates. Of the other antifungals tested, amphotericin B demonstrated in vitro good activity (MIC ranges 1-4 and 0.25-4 mg/mL against FOSC and FSSC, respectively). In contrast, the azoles demonstrated reduced susceptibility (MIC range 1- &gt;16 mg/mL).

MIC/MEC values (mcg/mL) for manogepix and other antifungals against FOSC and FSSC isolates

Conclusion

MGX demonstrated in vitro activity against FOSC and FSSC clinical isolates. Both changes in fungal morphology (MEC) and reductions in growth (MIC 50% inhibition) were observed. Clinical studies are ongoing to determine the efficacy of fosmanogepix in patients with invasive fungal infections.

Disclosures

Ashraf S. Ibrahim, PhD, Astellas Pharma (Research Grant or Support) Karen J. Shaw, PhD, Amplyx (Consultant)Forge Therapeutics (Consultant) Nathan P. Wiederhold, PharmD, Astellas (Grant/Research Support)BioMerieux (Grant/Research Support)Cepheid (Grant/Research Support)Covance (Grant/Research Support)F2G (Grant/Research Support)Gilead (Speaker’s Bureau)Mayne Pharma (Advisor or Review Panel member)Sfunga (Grant/Research Support)

Differential Thermotolerance Adaptation between Species of Coccidioides

Coccidioidomycosis, or Valley fever, is caused by two species of dimorphic fungi. Based on molecular phylogenetic evidence, the genus Coccidioides contains two reciprocally monophyletic species: C. immitis and C. posadasii. However, phenotypic variation between species has not been deeply investigated. We therefore explored differences in growth rate under various conditions. A collection of 39 C. posadasii and 46 C. immitis isolates, representing the full geographical range of the two species, was screened for mycelial growth rate at 37 °C and 28 °C on solid media. The radial growth rate was measured for 16 days on yeast extract agar. A linear mixed effect model was used to compare the growth rate of C. posadasii and C. immitis at 37 °C and 28 °C, respectively. C. posadasii grew significantly faster at 37 °C, when compared to C. immitis; whereas both species had similar growth rates at 28 °C. These results indicate thermotolerance differs between these two species. As the ecological niche has not been well-described for Coccidioides spp., and disease variability between species has not been shown, the evolutionary pressure underlying the adaptation is unclear. However, this research reveals the first significant phenotypic difference between the two species that directly applies to ecological research.

Trichosporonosis Presenting as an Exophytic Cutaneous Mass Lesion

Opportunistic fungal pathogens have increased in frequency with the growing immunosuppressed population. New and emerging pathogens, including the rare yeasts, continue to cause significant morbidity and mortality and frequently develop despite prophylaxis with antifungal agents. We report a previously unreported manifestation of disseminated trichosporonosis. Our patient with underlying acute myeloid leukemia presented with as an exophytic toe lesion found secondary to Trichosporon asahii. We highlight the need for a high index of suspicion to diagnose breakthrough infections and the need for aggressive treatment.

Isavuconazole as Primary Antifungal Prophylaxis in Patients With Acute Myeloid Leukemia or Myelodysplastic Syndrome: An Open-label, Prospective, Phase 2 Study

BACKGROUND

Mold-active primary antifungal prophylaxis (PAP) is routinely recommended in neutropenic patients with newly diagnosed acute myeloid leukemia (AML) or high-risk myelodysplastic syndrome (MDS) undergoing remission-induction chemotherapy (RIC). Isavuconazole (ISAV) is an extended spectrum mold-active triazole and has superior tolerability and fewer significant drug-drug interactions compared with other triazoles.

METHODS

In our investigator-initiated, phase 2 trial, treatment-naive adult patients with AML or MDS starting RIC received ISAV per the dosing recommendations in the US label until neutrophil recovery (absolute neutrophil count [ANC] ≥ 0.5 × 109/L) and attainment of complete remission, occurrence of invasive fungal infection (IFI), or for a maximum of 12 weeks. The primary endpoint was the incidence of proven/probable IFI during ISAV PAP and up to 30 days after the last dose.

RESULTS

Sixty-five of 75 enrolled patients received ISAV PAP (median age, 67 years, median ANC at enrollment, 0.72 × 109/L). Thirty-two patients (49%) received oral targeted leukemia treatments (venetoclax, FTL3 inhibitors). Including the 30-day follow-up period, probable/proven and possible IFIs were encountered in 4 (6%) and 8 patients (12%), respectively. ISAV trough serum concentrations were consistently > 1 µg/mL, showed low intraindividual variation, and were not significantly influenced by chemotherapy regimen. Tolerability of ISAV was excellent, with only 3 cases (5%) of mild to moderate elevations of liver function tests and no QTc prolongations.

CONCLUSIONS

ISAV is a safe and effective alternative for PAP in patients with newly diagnosed AML/MDS undergoing RIC in the era of recently approved or emerging small-molecule antileukemia therapies.

CLINICAL TRIALS REGISTRATION

NCT03019939.

Rapid and Low-Cost Culture-Based Method for Diagnosis of Mucormycosis Using a Mouse Model

Prompt and targeted antifungal treatment has a positive impact on the clinical outcome of mucormycosis; however, current diagnostic tools used in histopathology laboratories often fail to provide rapid results. Rapid culture-based strategies for early diagnosis of Mucorales infections, which may influence treatment decisions, are urgently needed. Herein, we evaluated a microculture assay for the early diagnosis of mucormycosis in an immunocompetent murine model of disseminated infection, by comparing it with traditional diagnostic methods. The assay specificity was assessed using blood (n = 90) and tissue (n = 90) specimens obtained from mice infected with Rhizopus arrhizus using different inoculum sizes [1 × 10⁴, 1 × 10⁵, and 1 × 10⁶ colony forming units (CFUs)/mouse] and blood (n = 15) and tissue specimens (n = 15) from uninfected mice. Surprisingly, 26 of 90 (28.9%) blood samples revealed positive results by microculture, whereas all blood samples were negative when assayed by conventional culture. The overall positive conventional culture rate for the mouse tissue (kidney) samples was 31.1% (28/90). The calculated sensitivity for kidney microculture was 98.8% [95% confidence interval (CI) 96.6–100], with an assay specificity of 100%. Hence, the microculture assay may be useful for rapid culturing and diagnosis of mucormycosis caused by R. arrhizus directly in blood and tissue samples. Hence, this method may allow for the timely administration of an appropriate treatment.

A Novel Exophiala Species Associated With Disseminated Granulomatous Inflammation in a Captive Eastern Hellbender (Cryptobranchus alleganiensis alleganiensis)

The genus Exophiala is composed of ubiquitous, pigmented, saprotrophic fungi and includes both terrestrial and waterborne species. Though Exophiala species are generally considered opportunistic pathogens, exophialosis can be an important cause of morbidity and mortality in aquatic and semi-aquatic species. Over a 6-year period, a captive 32-year-old male eastern hellbender (Cryptobranchus alleganiensis alleganiensis), was treated for recurring, slow growing, ventral midline cutaneous masses. Excisional biopsies were characterized histologically by granulomatous dermatitis with low numbers of intralesional, pigmented fungal conidia and hyphae. Bacterial and fungal cultures of the masses and skin were negative on two separate submissions. Polymerase chain reaction amplification of a short fragment of the fungal 28S large subunit (LSU) ribosomal RNA was positive with 100% nucleotide sequence identity to several species of Exophiala. Following recurrence after successive rounds of antifungal therapy, euthanasia was elected. At necropsy, similar dermal granulomatous inflammation and intralesional pigmented fungal elements as observed in excisional biopsies formed a thick band in the dermis and extended through the coelomic body wall. Visceral dissemination was noted in the lung and kidney. Postmortem DNA sequence analysis of a large portion of the fungal LSU as well as the internal transcribed spacer (ITS) from a portion of frozen affected dermis identified the fungus as a novel species, Exophiala sp. 1 (UTHSCSA R-5437).

Blastomyces helicus, a New Dimorphic Fungus Causing Fatal Pulmonary and Systemic Disease in Humans and Animals in Western Canada and the United States

Background

Blastomyces helicus (formerly Emmonsia helica) is a dimorphic fungus first isolated from a man with fungal encephalitis in Alberta, Canada. The geographic range, epidemiology, and clinical features of disease are unknown.

Methods

We reviewed human and veterinary isolates of B. helicus identified among Blastomyces and Emmonsia isolates at the University of Alberta Microfungus Collection and Herbarium, University of Texas Health San Antonio’s Fungus Testing Laboratory, and Associated Regional and University Pathologists Laboratories. Isolates were selected based on low Blastomyces dermatitidis DNA probe values and/or atypical morphology. Species identification was confirmed for most isolates by DNA sequence analysis of the internal transcribed spacer with or without D1/D2 ribosomal RNA regions. Epidemiological and clinical data were analyzed.

Results

We identified isolates from 10 human and 5 veterinary cases of B. helicus infection; all were referred from western regions of Canada and the United States. Isolates remained sterile in culture, producing neither conidia nor sexual spores in the mycelial phase, but often producing coiled hyphae. Isolates were most frequently cultured from blood and bronchoalveolar lavage in humans and lungs in animals. Most infected persons were immunocompromised. Histopathological findings included pleomorphic, small or variably sized yeast-like cells, with single or multiple budding, sometimes proliferating to form short, branching, hyphal-like elements. Disease carried a high case-fatality rate.

Conclusions

Blastomyces helicus causes fatal pulmonary and systemic disease in humans and companion animals. It differs from B. dermatitidis in morphological presentation in culture and in histopathology, by primarily affecting immunocompromised persons, and in a geographic range that includes western regions of North America.

In Vitro Activity of Essential Oils Against Gram-Positive and Gram-Negative Clinical Isolates, Including Carbapenem-Resistant Enterobacteriaceae

Background

There is increasing demand for compounds to treat antimicrobial-resistant pathogens, and essential oils have gained interest. Moreover, previous studies have demonstrated antimicrobial activity of these nonpharmaceutical products. We investigated the activity of essential oils against multiresistant bacteria and other clinical isolates to evaluate the potential of their use topically and/or internally for treatment of bacterial infections.

Methods

We studied the in vitro activity of 10 essential oils and 1 essential oil blend against clinical isolates including extended-spectrum beta-lactamase-producing Enterobacteriaceae, carbapenem-resistant Enterobacteriaceae, multidrug-resistant Pseudomonas aeruginosa, and methicillin-resistant Staphylococcus aureus.

Results

Essential oils of oregano, thyme, cinnamon bark, and lemongrass had the largest zones of inhibition against Gram-positive organisms, whereas cinnamon bark had the largest zone of inhibition against P aeruginosa. Oregano, thyme, and cinnamon bark had the largest zones of inhibition against Enterobacteriaceae.

Conclusions

Essential oils have promising in vitro activity that warrants further study of their activity and use in the clinical setting.

Global guideline for the diagnosis and management of mucormycosis: an initiative of the European Confederation of Medical Mycology in cooperation with the Mycoses Study Group Education and Research Consortium

Mucormycosis is a difficult to diagnose rare disease with high morbidity and mortality. Diagnosis is often delayed, and disease tends to progress rapidly. Urgent surgical and medical intervention is lifesaving. Guidance on the complex multidisciplinary management has potential to improve prognosis, but approaches differ between health-care settings. From January, 2018, authors from 33 countries in all United Nations regions analysed the published evidence on mucormycosis management and provided consensus recommendations addressing differences between the regions of the world as part of the "One World One Guideline" initiative of the European Confederation of Medical Mycology (ECMM). Diagnostic management does not differ greatly between world regions. Upon suspicion of mucormycosis appropriate imaging is strongly recommended to document extent of disease and is followed by strongly recommended surgical intervention. First-line treatment with high-dose liposomal amphotericin B is strongly recommended, while intravenous isavuconazole and intravenous or delayed release tablet posaconazole are recommended with moderate strength. Both triazoles are strongly recommended salvage treatments. Amphotericin B deoxycholate is recommended against, because of substantial toxicity, but may be the only option in resource limited settings. Management of mucormycosis depends on recognising disease patterns and on early diagnosis. Limited availability of contemporary treatments burdens patients in low and middle income settings. Areas of uncertainty were identified and future research directions specified.

2121. Isavuconazole (ISAV) as Primary Anti-Fungal Prophylaxis (PAP) in Patients with Acute Myeloid Leukemia (AML) or Myelodysplastic Syndrome (MDS): An Open-Label, Prospective Study

Background

Mold-active antifungal prophylaxis (ppx) is recommended in neutropenic patients with newly diagnosed AML or MDS. ISAV is an extended spectrum triazole with superior tolerability, reliability of absorption, fewer drug–drug interactions, lack of QT_c prolongation or need for therapeutic drug monitoring, approved for the treatment of invasive aspergillosis (IA) and mucormycosis. NCT03019939 is an investigator-initiated, phase 2 trial of PAP with ISAV in patients with AML/MDS.

Methods

Treatment-naïve adult patients with AML or MDS initiating remission-induction chemotherapy (RIC) received ISAV per the dosing recommendations in the United States label until recovery from neutropenia (neutrophils (ANC) ≥ 0.5 × 10⁹/L) and attainment of complete remission (CR), occurrence of proven or probable invasive fungal infection (IFI, EORTC/MSG criteria), or for a maximum of 12 weeks. The primary endpoint was incidence of proven/probable IFI during the study period (up to 30 days from the last dose of ISAV).

Results

67 patients were enrolled (April 28, 2017 to February 14, 2019) and 60 patients were eligible for assessment (median age 67 years, 57 patients with AML, median ANC on enrollment was 660). Reasons for study completion were achievement of CR with ANC recovery (n = 35), completion of 12 weeks of PAP (n = 9), possible IFI (n = 7), investigator decision (n = 3), death (n = 2, 1 disease progression, 1 cardiac arrest), proven/probable IFI (n = 3), and mild transaminitis, possibly ISAV-related (n = 2). The median durations of neutropenia and ISAV ppx were 33 (7–86) and 31 (7–86) days, respectively. One microbiologically-proven (gluteal abscess due to Candida glabrata) and 2 cases of probable breakthrough IFIs (probable IA with positive galactomannan) occurred (IFI incidence 5%). ISAV trough serum concentrations were available in 31 patients on both day 8 (median 3.74 µg/mL, 2.03–7.65) and day 15 (median 4.10 µg/mL, 2.17–9.25), and were not significantly different.

Conclusion

ISAV is a safe and effective alternative for PAP in patients with newly diagnosed AML/MDS undergoing RIC, with a breakthrough (proven/probable) IFI rate of 5%. ISAV serum levels were adequate in patients with AML/MDS undergoing RIC. Pharmacological features make ISAV attractive for PAP in the era of recently approved or emerging small-molecule AML therapies.

Disclosures

All authors: No reported disclosures.

Rezafungin (CD101) demonstrates potent in vitro activity against Aspergillus, including azole-resistant Aspergillus fumigatus isolates and cryptic species

Background

Rezafungin is an investigational echinocandin under development for the treatment and prevention of invasive fungal infections, with a long half-life in humans (∼130 h) and potent in vitro activity against Aspergillus spp. Our objective was to further evaluate its activity against Aspergillus fumigatus isolates, including azole-resistant isolates and cryptic Aspergillus spp.

Methods

Clinical isolates of Aspergillus were used, including 15 WT and 31 azole-resistant A. fumigatus, 11 Aspergillus lentulus, 5 each of Aspergillus thermomutatus and Aspergillus udagawae and 11 Aspergillus calidoustus. Minimum effective concentrations (MECs) and MICs of rezafungin, caspofungin, micafungin, posaconazole and voriconazole were determined by CLSI M38-A2 broth microdilution. Differences in geometric mean (GM) MEC/MIC values were assessed for significance by ANOVA.

Results

Rezafungin GM MECs for A. fumigatus were 0.024 and 0.043 mg/L for WT and azole-resistant isolates, respectively. Rezafungin was also active against cryptic species, including A. lentulus (0.016 mg/L), A. calidoustus (0.044 mg/L), A. thermomutatus (MEC range ≤0.015-0.25 mg/L) and A. udagawae (≤0.015-0.03 mg/L). This activity was similar to that of caspofungin and micafungin with the exception of A. calidoustus, against which rezafungin was more potent than caspofungin (GM MEC 0.044 versus 0.468 mg/L; P < 0.0001).

Conclusions

Rezafungin demonstrated potent in vitro activity against Aspergillus spp., including azole-resistant A. fumigatus isolates and cryptic species with elevated posaconazole and voriconazole MICs. Additional studies are warranted to determine whether the in vitro activity translates into in vivo efficacy against infections caused by resistant Aspergillus isolates.