Cutaneous Lagenidium deciduum infection in a patient with relapsed acute myeloid leukemia

BACKGROUND

Lagenidium deciduum is an oomycete that can cause infections in mammals that present similarly to pythiosis and mucormycosis. Most of the existing case reports have occurred in canines and have been fatal. In animals, medical therapy has not been successful, so surgical excision is the mainstay of treatment. Lagenidium sp. infections in humans are rare. There is only one case of a human Lagenidium sp. infection in the literature, and it presented as an ocular infection. The human ocular infection was resistant to medical therapy and required a penetrating keratoplasty for cure. Additional reports of effective therapy are needed to guide management of this emerging pathogen. We present the first case of a cutaneous Lagenidium deciduum infection in a human patient, which is also the first documented case of a Lagenidium deciduum infection in an immunocompromised host of any species.

CASE PRESENTATION

An 18-year-old female with relapsed acute myeloid leukemia, awaiting a haploidentical stem cell transplant, presented with erythematous cutaneous lesions on her left hip and bilateral buttocks that enlarged and blackened over several days. About 1 week later, boil-like lesions appeared on her bilateral buttocks. The skin lesions were initially presumed to be bacterial in origin, so the patient was treated with clindamycin and cefepime with little improvement. Upon further investigation, fungal cultures and skin biopsies revealed aseptate hyphae, so the patient was switched to isavuconazole and amphotericin B due to concern for mucormycosis. Phenotypic characterization and DNA sequencing were performed by the Fungus Testing Laboratory, University of Texas Health Science Center at San Antonio, which identified the causal fungal organism as Lagenidium deciduum. All of her cutaneous lesions were surgically excised, and the patient was treated with micafungin, terbinafine, doxycycline, and azithromycin. Micafungin and terbinafine were continued until she achieved engraftment post-transplant.

CONCLUSIONS

We report the first successful treatment of a human Lagenidium infection in an immunocompromised host through a combination of aggressive surgical excision and prolonged antifungal therapy during the prolonged neutropenia associated with allogeneic stem cell transplant. Prompt diagnosis and management may prevent disseminated oomycosis.

Universal digital high-resolution melting for the detection of pulmonary mold infections

Invasive mold infections (IMIs) are associated with high morbidity, particularly in immunocompromised patients, with mortality rates between 40% and 80%. Early initiation of appropriate antifungal therapy can substantially improve outcomes, yet early diagnosis remains difficult to establish and often requires multidisciplinary teams evaluating clinical and radiological findings plus supportive mycological findings. Universal digital high-resolution melting (U-dHRM) analysis may enable rapid and robust diagnoses of IMI. A universal fungal assay was developed for U-dHRM and used to generate a database of melt curve signatures for 19 clinically relevant fungal pathogens. A machine learning algorithm (ML) was trained to automatically classify these pathogen curves and detect novel melt curves. Performance was assessed on 73 clinical bronchoalveolar lavage samples from patients suspected of IMI. Novel curves were identified by micropipetting U-dHRM reactions and Sanger sequencing amplicons. U-dHRM achieved 97% overall fungal organism identification accuracy and a turnaround time of ~4 hrs. U-dHRM detected pathogenic molds (Aspergillus, Mucorales, Lomentospora, and Fusarium) in 73% of 30 samples classified as IMI, including mixed infections. Specificity was optimized by requiring the number of pathogenic mold curves detected in a sample to be >8 and a sample volume to be 1 mL, which resulted in 100% specificity in 21 at-risk patients without IMI. U-dHRM showed promise as a separate or combination diagnostic approach to standard mycological tests. U-dHRM's speed, ability to simultaneously identify and quantify clinically relevant mold pathogens in polymicrobial samples, and detect emerging opportunistic pathogens may aid treatment decisions, improving patient outcomes.

IMPORTANCE

Improvements in diagnostics for invasive mold infections are urgently needed. This work presents a new molecular detection approach that addresses technical and workflow challenges to provide fast pathogen detection, identification, and quantification that could inform treatment to improve patient outcomes.

Disseminated Aspergillus citrinoterreus and concurrent localized dermal phaeohyphomycosis in an immunosuppressed dog

Key Clinical message

We report on a dog with immune-mediated hemolytic anemia (IMHA) treated with immunomodulatory therapy that developed phaeohyphomycosis and Aspergillus citrinoterreus infections. This is the first reported case of A. citrinoterreus in dogs. It details cytological and microbiological findings leading to diagnosis and highlights the importance of investigating new lesions in immunocompromised patients.

Abstract

A 5-year-old Staffordshire terrier mix treated with immunosuppressive therapy for IMHA was diagnosed with concurrent disseminated A. citrinoterreus and localized Curvularia lunata infections. This case highlights the potential development of multiple concurrent opportunistic fungal infections and is the first reported case of A. citrinoterreus infection in a dog.

A conceptual framework for nomenclatural stability and validity of medically important fungi: a proposed global consensus guideline for fungal name changes supported by ABP, ASM, CLSI, ECMM, ESCMID-EFISG, EUCAST-AFST, FDLC, IDSA, ISHAM, MMSA, and MSGERC

The rapid pace of name changes of medically important fungi is creating challenges for clinical laboratories and clinicians involved in patient care. We describe two sources of name change which have different drivers, at the species versus the genus level. Some suggestions are made here to reduce the number of name changes. We urge taxonomists to provide diagnostic markers of taxonomic novelties. Given the instability of phylogenetic trees due to variable taxon sampling, we advocate to maintain genera at the largest possible size. Reporting of identified species in complexes or series should where possible comprise both the name of the overarching species and that of the molecular sibling, often cryptic species. Because the use of different names for the same species will be unavoidable for many years to come, an open access online database of the names of all medically important fungi, with proper nomenclatural designation and synonymy, is essential. We further recommend that while taxonomic discovery continues, the adaptation of new name changes by clinical laboratories and clinicians be reviewed routinely by a standing committee for validation and stability over time, with reference to an open access database, wherein reasons for changes are listed in a transparent way.

Universal Digital High Resolution Melt for the detection of pulmonary mold infections

Background

Invasive mold infections (IMIs) such as aspergillosis, mucormycosis, fusariosis, and lomentosporiosis are associated with high morbidity and mortality, particularly in immunocompromised patients, with mortality rates as high as 40% to 80%. Outcomes could be substantially improved with early initiation of appropriate antifungal therapy, yet early diagnosis remains difficult to establish and often requires multidisciplinary teams evaluating clinical and radiological findings plus supportive mycological findings. Universal digital high resolution melting analysis (U-dHRM) may enable rapid and robust diagnosis of IMI. This technology aims to accomplish timely pathogen detection at the single genome level by conducting broad-based amplification of microbial barcoding genes in a digital polymerase chain reaction (dPCR) format, followed by high-resolution melting of the DNA amplicons in each digital reaction to generate organism-specific melt curve signatures that are identified by machine learning.

Methods

A universal fungal assay was developed for U-dHRM and used to generate a database of melt curve signatures for 19 clinically relevant fungal pathogens. A machine learning algorithm (ML) was trained to automatically classify these 19 fungal melt curves and detect novel melt curves. Performance was assessed on 73 clinical bronchoalveolar lavage (BAL) samples from patients suspected of IMI. Novel curves were identified by micropipetting U-dHRM reactions and Sanger sequencing amplicons.

Results

U-dHRM achieved an average of 97% fungal organism identification accuracy and a turn-around-time of 4hrs. Pathogenic molds (Aspergillus, Mucorales, Lomentospora and Fusarium) were detected by U-dHRM in 73% of BALF samples suspected of IMI. Mixtures of pathogenic molds were detected in 19%. U-dHRM demonstrated good sensitivity for IMI, as defined by current diagnostic criteria, when clinical findings were also considered.

Conclusions

U-dHRM showed promising performance as a separate or combination diagnostic approach to standard mycological tests. The speed of U-dHRM and its ability to simultaneously identify and quantify clinically relevant mold pathogens in polymicrobial samples as well as detect emerging opportunistic pathogens may provide information that could aid in treatment decisions and improve patient outcomes.

S2.3c High-resolution digital DNA melting: a breakthrough in diagnosing IMI?

 

S2.3 Novel diagnostic tools for invasive mold infection, September 21, 2022, 3:00 PM - 4:30 PM

Invasive mold infections (IMIs) such as Aspergillosis, Mucormycosis, Fusariosis, and Lomentosporiosis have emerged as important pathogens in immunocompromised patients, with mortality rates as high as 50% to nearly 80% for these infections. Outcomes can be substantially improved with early initiation of appropriate antifungal therapy, yet early diagnosis remains difficult to establish and often requires multidisciplinary teams evaluating clinical and radiological findings plus supportive microbiologic findings. Conventional fungal culture and PCR techniques are limited by low sensitivity, long turn-around time, and are insufficient for differentiating between infection and colonization. Other non-culture-based tests, such as the Galactomannan test, are available only for invasive aspergillosis and are limited by imperfect test performance. Better and more rapid diagnostics are needed to enable early diagnosis and targeted treatment of IMIs and improve survival.

We have developed a new technology called digital high resolution melting analysis (dHRM) to enable a rapid and robust diagnosis of IMI. This technology accomplishes fast genotyping of fungal genomic sequences in clinical samples by: (1) conducting broad-based amplification of fungal genes in a digital PCR format, and (2) conducting high-resolution melting of the DNA amplicons in each digital reaction. High resolution melting measures the fluorescence of a saturating intercalating dye as dPCR-amplified fungal DNA fragments are rapidly heated and disassociated, producing sequence-defined melt curves in a closed reaction format. These melt curves serve as unique fungal ‘fingerprints’, which allows us to correctly identify disease-causing pathogen(s) with an accuracy of 99%-100% through the use of machine learning methods trained to tolerate variations in reaction conditions. This approach provides a simple, low-cost, fast, and robust method for pathogen identification.

Here, we will present the performance of this new technology on clinical bronchoalveolar lavage (BAL) samples from patients with and without IMI. A total of 75 patient BAL samples were tested, coming from 30 patients with proven (n = 1), probable (n = 25), or putative (n = 4) invasive pulmonary aspergillosis (IPA) infections, and from 45 patients classified as not having IPA (n = 4 possible IPA and n = 41 no IPA). Our results show that dHRM was able to reliably differentiate between different Aspergillus spp. and was also able to identify Aspergillus spp. in BAL samples from patients with probable IPA where qPCR had resulted in negative. In a few instances, it also detected rare molds in culture-negative samples and multiple Aspergillus spp. within one BAL sample, a phenomenon that has been previously described in cultures. Interestingly, there was no clear correlation between dHRM results and BAL galactomannan levels, suggesting that dHRM may serve as an independent method allowing for a combined diagnostic approach. While further validation and optimization are needed, these results suggest that dHRM is a promising new diagnostic technology capable of providing clinically relevant information within 2-3 h.

The importance of antimicrobial resistance in medical mycology

Prior to the SARS-CoV-2 pandemic, antibiotic resistance was listed as the major global health care priority. Some analyses, including the O'Neill report, have predicted that deaths due to drug-resistant bacterial infections may eclipse the total number of cancer deaths by 2050. Although fungal infections remain in the shadow of public awareness, total attributable annual deaths are similar to, or exceeds, global mortalities due to malaria, tuberculosis or HIV. The impact of fungal infections has been exacerbated by the steady rise of antifungal drug resistant strains and species which reflects the widespread use of antifungals for prophylaxis and therapy, and in the case of azole resistance in Aspergillus, has been linked to the widespread agricultural use of antifungals. This review, based on a workshop hosted by the Medical Research Council and the University of Exeter, illuminates the problem of antifungal resistance and suggests how this growing threat might be mitigated.

Diagnosis from Tissue: Histology and Identification

The diagnosis and initiation of appropriate treatment against invasive fungal infections depend upon accurate identification of pathogens by pathologists and clinical microbiologists. Histopathology is often critical in providing diagnostic insight in patients with suspected fungal infections, and such findings are incorporated into the definitions of proven or probable disease caused by certain pathogens. Such examinations can offer provisional identifications of fungal organisms, which can help guide initial therapy while laboratory results are pending. Common etiologic agents of invasive mycoses may be recognized based on morphologic characteristics observed in tissue and biologic fluids, such as those obtained from bronchoalveolar lavage and bronchial washings. However, care should be taken in the interpretation of these findings, as there may be a false sense of the ability to correctly categorize fungal organisms to the genus or species level by morphologic features alone. Studies have demonstrated discordant results between histopathology and laboratory results due to overlapping morphologic features, morphologic mimics, and sampling errors. Thus, histopathology plays an integral role in providing a differential of potential fungal pathogens but must be combined with results from laboratory studies, including cultures, antigen tests, serology, and molecular assays, in order to improve accuracy in the identification of etiologic agents of fungal infections. Inaccurate identification of the infecting organism can lead to inappropriate antifungal therapy and possibly poor clinical outcomes.

The Antifungal Pipeline: Fosmanogepix, Ibrexafungerp, Olorofim, Opelconazole, and Rezafungin

The epidemiology of invasive fungal infections is changing, with new populations at risk and the emergence of resistance caused by the selective pressure from increased usage of antifungal agents in prophylaxis, empiric therapy, and agriculture. Limited antifungal therapeutic options are further challenged by drug-drug interactions, toxicity, and constraints in administration routes. Despite the need for more antifungal drug options, no new classes of antifungal drugs have become available over the last 2 decades, and only one single new agent from a known antifungal class has been approved in the last decade. Nevertheless, there is hope on the horizon, with a number of new antifungal classes in late-stage clinical development. In this review, we describe the mechanisms of drug resistance employed by fungi and extensively discuss the most promising drugs in development, including fosmanogepix (a novel Gwt1 enzyme inhibitor), ibrexafungerp (a first-in-class triterpenoid), olorofim (a novel dihyroorotate dehydrogenase enzyme inhibitor), opelconazole (a novel triazole optimized for inhalation), and rezafungin (an echinocandin designed to be dosed once weekly). We focus on the mechanism of action and pharmacokinetics, as well as the spectrum of activity and stages of clinical development. We also highlight the potential future role of these drugs and unmet needs.

A revision of malbranchea-like fungi from clinical specimens in the United States of America reveals unexpected novelty

The fungi of the order Onygenales can cause important human infections; however, their taxonomy and worldwide occurrence is still little known. We have studied and identified a representative number of clinical fungi belonging to that order from a reference laboratory in the USA. A total of 22 strains isolated from respiratory tract (40%) and human skin and nails (27.2%) showed a malbranchea-like morphology. Six genera were phenotypically and molecularly identified, i.e. Auxarthron/Malbranchea (68.2%), Arachnomyces (9.1%), Spiromastigoides (9.1%), and Currahmyces (4.5%), and two newly proposed genera (4.5% each). Based on the results of the phylogenetic study, we synonymized Auxarthron with Malbranchea, and erected two new genera: Pseudoarthropsis and Pseudomalbranchea. New species proposed are: Arachnomyces bostrychodes, A. graciliformis, Currahmyces sparsispora, Malbranchea gymnoascoides, M. multiseptata, M. stricta, Pseudoarthropsis crassispora, Pseudomalbranchea gemmata, and Spiromastigoides geomycoides, along with a new combination for Malbranchea gypsea. The echinocandins showed the highest in vitro antifungal activity against the studied isolates, followed by terbinafine and posaconazole; in contrast, amphotericin B, fluconazole, itraconazole and 5-fluorocytosine were less active or lacked in vitro activity against these fungi.

Disseminated Rasamsonia argillacea species complex infections in 8 dogs

Background

Clinical features, treatment, and outcome of opportunistic infections with Rasamsonia spp., a nonpigmented filamentous mold, are not well documented in dogs.

Objectives

Describe clinical, radiographic, pathologic features, and outcome of dogs with disseminated Rasamsonia species complex infections.

Animals

Eight client‐owned dogs.

Methods

Retrospective case series. Medical records were reviewed to describe signalment, history, clinicopathologic and imaging findings, microbiologic and immunologic results, cyto‐ and histopathologic diagnoses, treatment, and outcome.

Results

Presenting complaints were nonspecific with anorexia (n = 5) and back pain (n = 4) most common. Five dogs were German Shepherd dogs. Six dogs had multifocal discospondylitis and 2 had pleural effusion. Six dogs had Rasamsonia piperina and 2 had Rasamsonia argillacea infections with isolates identified using DNA sequencing. Rasamsonia spp. were isolated by urine culture in 5 of 7 dogs. Five of 6 dogs had positive serum Aspergillus galactomannan antigen enzyme immunoassay (EIA) results. Median survival time was 82 days, and 317 days for dogs that survived to discharge. Four died during initial hospitalization (median survival, 6 days). All isolates had low minimum effective concentrations (MECs) to echinocandins with variable minimum inhibitory concentrations (MICs) for azole antifungal drugs.

Conclusions and Clinical Importance

Rasamsonia spp. infections in dogs are associated with multisystemic disease involving the vertebral column, central nervous system, kidneys, spleen, lymph nodes, lungs, and heart. The infection shares clinical features with other systemic mold infections and can be misidentified when using phenotypical microbiologic methods. Molecular techniques are required to identify the organism and guide appropriate antifungal treatment.

First Reported Case of Invasive Cutaneous Penicillium cluniae Infection in a Patient With Acute Myelogenous Leukemia: A Case Report and Literature Review

Certain Penicillium species are emerging opportunistic pathogens. While these can be common causes of airborne contamination of clinical cultures, an increasing number of reports describe clinically significant disease in the immunocompromised population, particularly in patients with hematologic malignancy. The typical site of infection is respiratory, but disseminated infection is also reported with some frequency. Therefore, culture growth of Penicillium in respiratory and other clinical samples from immunocompromised patients requires thorough investigation with clinical correlation. Here we report a case of angioinvasive Penicillium cluniae infection of the right shin in a patient with acute myeloid leukemia and review reported cases of invasive Penicillium infection (excluding Talaromyces marneffei) in hematologic malignancy patients to characterize the emerging pathogen in this vulnerable population.

Efficacy and Associated Drug Exposures of Isavuconazole and Fluconazole in an Experimental Model of Coccidioidomycosis

Coccidioides spp. are important pathogens in regions where they are endemic, and new treatment options are needed. Here, isavuconazonium sulfate (ISAVUSULF) and fluconazole (FLU) were evaluated in experimental disseminated coccidioidomycosis to characterize drug exposures associated with efficacy. Broth macrodilution was performed on Coccidioides isolates to measure minimal effective concentrations (MEC) and minimal fungicidal concentrations (MFC). Mice were inoculated with Coccidioides posadasii (Silveira strain). Treatment started 4 days postinoculation. In model 1, mice were treated for 19 days, followed by 30 days of off-therapy observation, measuring survival through day 49 and residual fungal burden. Treatments included ISAVUSULF (prodrug; 186, 279, or 372 mg/kg twice daily), FLU (20 or 100 mg/kg once daily), and no treatment. Model 2 included 7-day treatment with ISAVUSULF (prodrug; 74.4, 111.6, or 148.8 mg/kg twice daily), FLU (20 or 100 mg/kg once daily), and no treatment. Serial plasma and tissues samples were obtained for pharmacokinetics (PK) and fungal burden measurement, respectively. Fifty percent minimal effective concentration (MEC50) values were 0.39 mg/liter (isavuconazole [ISAV]) and 12.5 mg/liter (FLU). Treatment with ISAVUSULF186 or with either FLU dose resulted in higher survival compared to that in the untreated group. Treatment with ISAVUSULF186 or ISAVUSULF279 twice daily or FLU100 reduced fungal burden in all organs (model 1). In model 2, a >1 log10 CFU/organ reduction was demonstrated, with ISAV area under the concentration-time curve (AUC) values achieved with 111.6 mg/kg twice daily (56.8 mg · h/liter) in the spleen and liver. FLU AUC values of 100 and 500 mg·h/liter for 20 and 100 mg/kg doses, respectively, resulted in a >1 log10 CFU/organ mean reduction in all organs. ISAVUSULF and FLU improved survival and reduced fungal burden. Increasing plasma drug exposures resulted in decreases in fungal burden.

Three new Curvularia species from clinical and environmental sources

Curvularia is a Pleosporalean monophyletic genus with a great diversity of species, including relevant phytopathogenic, animal and human pathogenic fungi. However, their microscopic identification is difficult due to overlapping morphological features amongst species. In recent years, multi-locus sequence analysis using the ITS region of the rDNA and fragments of the genes gapdh and tef1 revealed numerous cryptic species, especially in isolates that commonly produced 3-septate conidia. Therefore, based on sequence analysis of the above-mentioned DNA barcodes recommended for species delineation in Curvularia, we propose three novel species, C.paraverruculosa, C.suttoniae and C.vietnamensis, isolated from soil, human clinical specimens and plant material, respectively, collected in different countries. These new species are morphologically characterised and illustrated in the present study. Curvulariaparaverruculosa differs from its counterparts, C.americana and C.verruculosa, mainly by its narrower conidia. Curvulariasuttoniae and C.vietnamensis are closely related to C.petersonii, but the former two have larger conidia.

Genomic characterization of Parengyodontium americanum sp. nov

Modern genome analysis and phylogenomic methods have increased the number of fungal species, as well as enhanced appreciation of the degree of diversity within the fungal kingdom. In this context, we describe a new Parengyodontium species, P. americanum, which is phylogenetically related to the opportunistic human fungal pathogen P. album. Five unusual fungal isolates were recovered from five unique and confirmed coccidioidomycosis patients, and these isolates were subsequently submitted to detailed molecular and morphological identification procedures to determine identity. Molecular and morphological diagnostic analyses showed that the isolates belong to the Cordycipitaceae. Subsequently, three representative genomes were sequenced and annotated, and a new species, P. americanum, was identified. Using various genomic analyses, gene family expansions related to novel compounds and potential for ability to grow in diverse habitats are predicted. A general description of the genomic composition of this newly described species and comparison of genome content with Beauveria bassiana, Isaria fumosorosea and Cordyceps militaris shows a shared core genome of 6371 genes, and 148 genes that appear to be specific for P. americanum. This work provides the framework for future investigations of this interesting fungal species.

Two new species of Gloniopsis (Hysteriales, Ascomycota) from clinical specimens: Morphological and molecular characterisation

BACKGROUND

The coelomycetes comprise a wide range of fungal species distributed in at least three different classes of the phylum Ascomycota. These are morphologically characterised by producing their conidia inside of fruiting bodies called pycnidia or acervuli, and only a reduced number of species are able to cause human infections. However, their identification in the clinical laboratory is often difficult, due to their few morphological features or because they remain sterile.

MATERIALS AND METHODS

In the present study, three isolates of coelomycetes of clinical origin were phenotypically and molecularly studied, by sequencing the D1-D2 fragment of the 28S nuclear ribosomal RNA (nrRNA) (LSU), the internal transcribed spacer region (ITS1-5.8S-ITS2) and a fragment of the translation elongation factor 1-alpha (tef1) genes.

RESULTS AND CONCLUSIONS

As result of the molecular analysis, the isolates were identified as belonging to the genus Gloniopsis (order Hysteriales, Dothideomycetes) but without the characteristics of any of the species described so far. Therefore, we propose the new species Gloniopsis percutanea and Gloniopsis pneumoniae. Furthermore, this study revealed that some isolates from clinical specimens identified previously as Rhytidhysteron spp. were misidentified, and considering the few studies in the order Hysteriales and the scarce number of sequences of phylogenetic markers, future revisions of this order should be performed to clarify their taxonomy and obtain a better identification from isolates involved in human mycoses.

Re-evaluation of Mycoleptodiscus species and morphologically similar fungi

Mycoleptodiscus includes plant pathogens, animal opportunists, saprobic and endophytic fungi. The present study presents the first molecular phylogeny and revision of the genus based on four loci, including ITS, LSU, rpb2, and tef1. An extensive collection of Mycoleptodiscus cultures, including ex-type strains from the CBS, IMI, MUCL, BRIP, clinical isolates from the USA, and fresh isolates from Brazil and Spain, was studied morphologically and phylogenetically to resolve their taxonomy. The study showed that Mycoleptodiscus sensu lato is polyphyletic. Phylogenetic analysis places Mycoleptodiscus in Muyocopronales (Dothideomycetes), together with Arxiella, Leptodiscella, Muyocopron, Neocochlearomyces, and Paramycoleptodiscus. Mycoleptodiscus terrestris, the type species, and M. sphaericus are reduced to synonyms, and one new species is introduced, M. suttonii. Mycoleptodiscus atromaculans, M. coloratus, M. freycinetiae, M. geniculatus, M. indicus, M. lateralis (including M. unilateralis and M. variabilis as its synonyms) and M. taiwanensis belong to Muyocopron (Muyocopronales, Dothideomycetes), and M. affinis, and M. lunatus to Omnidemptus (Magnaporthales, Sordariomycetes). Based on phylogenetic analyses we propose Muyocopron alcornii sp. nov., a fungus associated with leaf spots on Epidendrum sp. (Orchidaceae) in Australia, Muyocopron zamiae sp. nov. associated with leaf spots on Zamia (Zamiaceae) in the USA, and Omnidemptus graminis sp. nov. isolated from a grass (Poaceae) in Spain. Furthermore, Neomycoleptodiscus venezuelense gen. & sp. nov. is introduced for a genus similar to Mycoleptodiscus in Muyocopronaceae.

Species of Aspergillus section Aspergillus from clinical samples in the United States

The diversity of Aspergillus species in clinical samples is continuously increasing. Species under the former name Eurotium, currently accommodated in section Aspergillus of the genus Aspergillus, are xerophilic fungi widely found in the human environment and able to grow on substrates with low water activity. However, their prevalence in the clinical setting is poorly known. We have studied the presence of these species in a set of clinical samples from the United States using a multilocus sequence analysis based on the internal transcribed spacer (ITS) region of the rRNA, and fragments of the genes β-tubulin (BenA), calmodulin (CaM), and polymerase II second largest subunit (RPB2). A total of 25 isolates were studied and identified as follows: A. montevidensis (44%), A. chevalieri (36%), A. pseudoglaucus (8%), and A. costiformis (4%). A new species Aspergillus microperforatus is also proposed, which represented 8% of the isolates studied and is characterized by uniseriate conidial heads, subglobose to pyriform vesicles, rough conidia, globose to subglobose cleistothecia, and lenticular and smooth ascospores. The in vitro antifungal activity of eight clinically available antifungals was also determined against these isolates, with the echinocandins and posaconazole having the most potent activity.

Antifungal Susceptibility and Clinical Outcome in Neonatal Candidiasis

BACKGROUND

Invasive candidiasis is an important cause of sepsis in extremely low birth weight infants (ELBW, < 1000 g), is often fatal, and frequently results in neurodevelopmental impairment (NDI) among survivors. We sought to assess the antifungal minimum inhibitory concentration (MIC) distribution for Candida in ELBW infants and evaluate the association between antifungal resistance and death or NDI.

METHODS

This was a secondary analysis of a National Institute of Child Health and Human Development Neonatal Research Network study. MIC values were determined for fluconazole, amphotericin B and micafungin. NDI was assessed at 18-22 months adjusted age using the Bayley Scales of Infant Development. An infant was defined as having a resistant Candida isolate if ≥ 1 positive cultures from normally sterile sites (blood, cerebrospinal fluid, or urine) were resistant to ≥ 1 antifungal agent. In addition to resistance status, we categorized fungal isolates according to MIC values (low and high). The association between death/NDI and MIC level was determined using logistic regression, controlling for gestational age and Bayley Scales of Infant Development (II or III).

RESULTS

Among 137 ELBW infants with IC, MICs were determined for 308 isolates from 110 (80%) infants. Three Candida isolates from 3 infants were resistant to fluconazole. None were resistant to amphotericin B or micafungin. No significant difference in death, NDI, or death/NDI between groups with low and high MICs was observed.

CONCLUSIONS

Antifungal resistance was rare among infecting Candida isolates, and MIC level was not associated with increased risk of death or NDI in this cohort of ELBW infants.

Four new species of Talaromyces from clinical sources

The genus Talaromyces constitutes an important group of molds with species that are mainly found in soil, indoor environments and food products. Traditionally, it has been considered, together with Eupenicillium, the teleomorphic state of Penicillium. However, the taxonomy of these fungi has changed considerably, and Talaromyces currently includes sexually and asexually reproducing species. In a previous study of the occurrence of penicillium-like fungi from clinical samples in the USA, we used the combined phylogeny of the internal transcribed spacer (ITS) region of the rDNA and β-tubulin (BenA) gene to identify 31 isolates of Talaromyces, 85 of Penicillium and two of Rasamsonia. However, seven isolates of Talaromyces were assigned to the corresponding sections but not to any particular species. In this study, we have resolved the taxonomy of these isolates through a multilocus sequence analysis of the ITS, fragments of the BenA, calmodulin (CaM), and RNA polymerase II second largest subunit (RPB2) genes, and a detailed phenotypic study. As a result, four new species are described and illustrated, ie Talaromyces alveolaris, T. georgiensis, T. minnesotensis and T. rapidus.

Invasive Microsporum canis causing rhinitis and stomatitis in a cat

Microsporum canis is a pathogenic fungus that typically causes dermatophytosis in cats. This report describes a cat with a Microsporum canis infection causing invasive fungal rhinitis that extended through the hard palate, resulting in adjacent stomatitis. Treatment with itraconazole and terbinafine resolved the infection.

Development of a Candida glabrata dominant nutritional transformation marker utilizing the Aspergillus nidulans acetamidase gene (amdS)

The gene encoding Aspergillus nidulans acetamidase (amdS) was placed under control of Candida albicans ACT1 promoter and terminator sequences and then cloned into a plasmid containing C. glabrata ARS10,CEN8 or ARS10+CEN8 sequences. All plasmids transformed C. glabrata wild-type cells to acetamide+, with the ARS-only containing plasmid transforming cells at the highest frequencies (>1.0 × 10(4) transformants μg(-1)). Plasmids were rapidly lost under non-selective conditions with the frequency dependent on chromosomal element, thus recycling the acetamide- phenotype. The amdS plasmid was used to transform a set of clinical isolates resistant to a variety of antifungal drugs. All strains were successfully transformed to the acetamide+ phenotype at high frequency, confirming that this plasmid construct could be used as a simple dominant marker on virtually any strain. Gap repair experiments demonstrated that just as in Saccharomyces cerevisiae, gap repair functions efficiently inC. glabrata, suggesting that C. glabrata has numerous similarities toS. cerevisiae with regard to ease of molecular manipulation. The amdS system is inexpensive and efficient, and combined with existing C. glabrata plasmid elements, confers a high transformation frequency for C. glabrata with a phenotype that can be easily recycled.

Voriconazole and posaconazole therapy for experimental Candida lusitaniae infection

The in vitro activity of posaconazole (PSC) and voriconazole (VRC) was tested by using time-kill studies against 3 strains of Candida lusitaniae. Both drugs showed fungistatic activity against all strains. The efficacy of those compounds was evaluated by reducing kidney fungal burden and by determining (1→3)-β-d-glucan serum levels in a murine model of invasive infection of C. lusitaniae. The therapies tested were VRC at 10, 25, or 40 mg/kg/day and PSC at 5, 12.5, or 20 mg/kg/twice a day. All the dosages showed efficacy in a dose-dependant manner being high doses of both antifungals able to sterilize some kidneys after 10 days. With the exception of the strain FMR 9474, against which PSC was more effective than VRC, no differences in reducing tissue burden were found between the treatments. All doses of both antifungals were able to significantly reduce (1→3)-β-d-glucan serum levels with no significant differences between treatments and between the same doses of both drugs.

Multifocal Rhizopus microsporus lung infection following brush clearing

We report a case of pulmonary Rhizopus microsporus infection in a patient with untreated diabetes following brush clearing. The patient was successfully treated with a combined medical and surgical approach with complete resolution of the lung lesions and remains asymptomatic at 11-month follow-up.

Effect of amphotericin B and micafungin combination on survival, histopathology, and fungal burden in experimental aspergillosis in the p47phox-/- mouse model of chronic granulomatous disease

Chronic granulomatous disease (CGD) is an inherited disorder of the NADPH oxidase characterized by recurrent life-threatening bacterial and fungal infections. We characterized the effects of single and combination antifungal therapy on survival, histopathology, and laboratory markers of fungal burden in experimental aspergillosis in the p47phox-/- knockout mouse model of CGD. CGD mice were highly susceptible to intratracheal Aspergillus fumigatus challenge, whereas wild-type mice were resistant. CGD mice were challenged intratracheally with a lethal inoculum (1.25 x 10(4) CFU/mouse) of A. fumigatus and received one of the following regimens daily from day 0 to 4 after challenge (n = 19 to 20 per treatment group): (i) vehicle, (ii) amphotericin B (intraperitoneal; 1 mg/kg of body weight), (iii) micafungin (intravenous; 10 mg/kg), or (iv) amphotericin B plus micafungin. The rank order of therapeutic efficacy based on prolonged survival, from highest to lowest, was as follows: amphotericin B plus micafungin, amphotericin B alone, micafungin alone, and the vehicle. Lung histology showed pyogranulomatous lesions and invasive hyphae, but without hyphal angioinvasion or coagulative necrosis. Treatment with micafungin alone or combined with amphotericin B produced swelling of invasive hyphae that was not present in mice treated with the vehicle or amphotericin B alone. Assessment of lung fungal burden by quantitative PCR showed no significant difference between treatment groups. Serum galactomannan levels were at background despite documentation of invasive aspergillosis by histology. Our findings showed the superior efficacy of the amphotericin B and micafungin combination compared to either agent alone after A. fumigatus challenge and also demonstrated unique features of CGD mice as a model for experimental aspergillosis.

Attenuation of itraconazole fungicidal activity following preexposure of Aspergillus fumigatus to fluconazole

Fluconazole (FLC), a triazole with limited activity against Aspergillus species, is frequently used as prophylaxis in leukemia patients and bone marrow transplant recipients. Prior FLC use has been associated with an increasing incidence of invasive aspergillosis in these patients. We hypothesized that prior exposure of Aspergillus fumigatus to FLC could result in altered in vitro susceptibility of this fungus to other, more active triazoles. Thus, we performed serial passages of conidia of 10 clinical isolates of A. fumigatus (all itraconazole [ITC] susceptible) on FLC-containing yeast agar glucose plates. The MICs and minimal fungicidal concentrations (MFCs) of amphotericin B, FLC, ITC, and voriconazole (VRC) for A. fumigatus conidia were measured following four passages on FLC-containing medium according to the National Committee for Clinical Laboratory Standards microdilution method. Serial passages on FLC-containing plates resulted in a fourfold increase in the MFCs (but not the MICs) of ITC for nine isolates. The attenuated ITC fungicidal activity against A. fumigatus following FLC preexposure was medium independent and was also observed against FLC-preexposed A. fumigatus hyphae with the viability staining FUN-1 dye. Moreover, FLC preexposure of A. fumigatus conidia resulted in an analogous increase in the MFCs (but not the MICs) of VRC. Our findings suggest that preexposure of A. fumigatus to FLC attenuates the in vitro fungicidal activity of subsequent ITC use against it. This phenotypic adaptation is not captured by a routine MIC determination but requires MFC measurement. The in vivo significance of this in vitro phenomenon requires further investigation.

Genome-wide expression profiling reveals genes associated with amphotericin B and fluconazole resistance in experimentally induced antifungal resistant isolates of Candida albicans

OBJECTIVES

The aim of this study was to identify changes in the gene expression profile of Candida albicans associated with the acquisition of experimentally induced resistance to amphotericin B and fluconazole.

METHODS

C. albicans SC5314 was passed in increasing concentrations of amphotericin B to generate isolate SC5314-AR. Susceptibility testing by Etest revealed SC5314-AR to be highly resistant to both amphotericin B and fluconazole. The gene expression profile of SC5314-AR was compared with that of SC5314 using DNA microarray analysis. Sterol composition was determined for both strains.

RESULTS

Upon examination of MICs of antifungal compounds, it was found that SC5314-AR was resistant to both amphotericin B and fluconazole. By microarray analysis a total of 134 genes were found to be differentially expressed, that is up-regulated or down-regulated by at least 50%, in SC5314-AR. In addition to the cell stress genes DDR48 and RTA2, the ergosterol biosynthesis genes ERG5, ERG6 and ERG25 were up-regulated. Several histone genes, protein synthesis genes and energy generation genes were down-regulated. Sterol analysis revealed the prevalence of sterol intermediates eburicol and lanosterol in SC5314-AR, whereas ergosterol was the predominant sterol in SC5314.

CONCLUSION

Along with changes in expression of these ergosterol biosynthesis genes was the accumulation of sterol intermediates in the resistant strain, which would account for the decreased affinity of amphotericin B for membrane sterols and a decreased requirement for lanosterol demethylase activity in membrane sterol production. Furthermore, other genes are implicated as having a potential role in the polyene and azole antifungal resistant phenotype.