In Vitro Activity of Ibrexafungerp against a Collection of Clinical Isolates of Aspergillus, Including Cryptic Species and Cyp51A Mutants, Using EUCAST and CLSI Methodologies.

Ibrexafungerp is a new orally-available 1,3-ß-D-glucan synthesis inhibitor in clinical development. Its in vitro activity and that of amphotericin B, voriconazole, and micafungin were evaluated against a collection of 168 clinical isolates of Aspergillus spp., including azole-susceptible and azole-resistant (Cyp51A mutants) Aspergillus fumigatus sensu stricto (s.s.) and cryptic species of Aspergillus belonging to six species complexes showing different patterns of antifungal resistance, using EUCAST and CLSI antifungal susceptibility testing reference methods. Ibrexafungerp displayed low geometric means of minimal effective concentrations (MECs) against A. fumigatus s.s. strains, both azole susceptible (0.040 mg/L by EUCAST and CLSI versus 1.231 mg/L and 0.660 mg/L for voriconazole, respectively) and azole resistant (0.092 mg/L and 0.056 mg/L, EUCAST and CLSI, while those for voriconazole were 2.144 mg/L and 2.000 mg/L). Ibrexafungerp was active against most of the cryptic species of Aspergillus tested, yielding MEC values only comparable to those of micafungin. Nevertheless, this new compound exhibited a moderate activity against A. ustus complex species, MECs ≥ 0.5 mg/L against Aspergillus insuetus and Aspergillus keveii strains, and was inactive against the Aspergillus alliaceus isolates tested (MEC90s ≥ 16 mg/L). All in all, ibrexafungerp shows encouraging in vitro results against cryptic species of Aspergillus and azole-susceptible and azole resistant strains of A. fumigatus, some of which are difficult to treat using the available therapeutic options.

Examining Signatures of Natural Selection in Antifungal Resistance Genes Across Aspergillus Fungi.

Certain Aspergillus fungi cause aspergillosis, a set of diseases that typically affect immunocompromised individuals. Most cases of aspergillosis are caused by Aspergillus fumigatus, which infects millions of people annually. Some closely related so-called cryptic species, such as Aspergillus lentulus, can also cause aspergillosis, albeit at lower frequencies, and they are also clinically relevant. Few antifungal drugs are currently available for treating aspergillosis and there is increasing worldwide concern about the presence of antifungal drug resistance in Aspergillus species. Furthermore, isolates from both A. fumigatus and other Aspergillus pathogens exhibit substantial heterogeneity in their antifungal drug resistance profiles. To gain insights into the evolution of antifungal drug resistance genes in Aspergillus, we investigated signatures of positive selection in 41 genes known to be involved in drug resistance across 42 susceptible and resistant isolates from 12 Aspergillus section Fumigati species. Using codon-based site models of sequence evolution, we identified ten genes that contain 43 sites with signatures of ancient positive selection across our set of species. None of the sites that have experienced positive selection overlap with sites previously reported to be involved in drug resistance. These results identify sites that likely experienced ancient positive selection in Aspergillus genes involved in resistance to antifungal drugs and suggest that historical selective pressures on these genes likely differ from any current selective pressures imposed by antifungal drugs.

Draft Genome Sequences of Four Aspergillus Section Fumigati Clinical Strains.

Aspergillus fungi in section Fumigati include important human pathogens. Here, we sequenced the genomes of two strains of Aspergillus hiratsukae and two strains of Aspergillus felis The average genome sizes are 29.5 Mb for A. hiratsukae and 31.8 Mb for A. felis.

Point Mutations in the 14-α Sterol Demethylase Cyp51A or Cyp51C Could Contribute to Azole Resistance in Aspergillus flavus.

Infections caused by Aspergillus species are being increasingly reported. Aspergillus flavus is the second most common species within this genus causing invasive infections in humans, and isolates showing azole resistance have been recently described. A. flavus has three cyp51-related genes (cyp51A, cyp51B, and cyp51C) encoding 14-α sterol demethylase-like enzymes which are the target of azole drugs. In order to study triazole drug resistance in A. flavus, three strains showing reduced azole susceptibility and 17 azole susceptible isolates were compared. The three cyp51-related genes were amplified and sequenced. A comparison of the deduced Cyp51A, Cyp51B, and Cyp51C protein sequences with other protein sequences from orthologous genes in different filamentous fungi led to a protein identity that ranged from 50% to 80%. Cyp51A and Cyp51C presented several synonymous and non-synonymous point mutations among both susceptible and non-susceptible strains. However, two amino acid mutations were present only in two resistant isolates: one strain harbored a P214L substitution in Cyp51A, and another a H349R in Cyp51C that also showed an increase of cyp51A and cyp51C gene expression compared to the susceptible strain ATCC2004304. Isolates that showed reduced in vitro susceptibility to clinical azoles exhibited a different susceptibility profile to demethylation inhibitors (DMIs). Although P214L substitution might contribute to azole resistance, the role of H349R substitution together with changes in gene expression remains unclear.

Nationwide surveillance of azole-resistant Aspergillus fumigatus environmental isolates in Greece: detection of pan-azole resistance associated with the TR46/Y121F/T289A cyp51A mutation.

BACKGROUND: Acquired azole resistance (AR) in Aspergillus fumigatus emphasizes the importance of the One Health multisectorial approach. The prevalence of azole-resistant A. fumigatus in the environment of Greece is unknown. METHODS: Between October 2016 and September 2017, a total of 716 soil samples were collected from 23 provinces and screened for AR using azole-containing agar plates. Recovered isolates were macro-/microscopically identified and colonies were counted. Azole susceptibility testing of A. fumigatus species complex (SC) isolates was performed (EUCAST E.DEF9.3.1). Azole-resistant A. fumigatus isolates were subjected to confirmatory molecular identification and sequencing of the cyp51A gene. RESULTS: No yeasts were recovered, while multiple moulds grew on 695 (97%) samples. Overall, zygomycetes (most non-Mucor genera) grew on 432 (60%) samples, while Aspergillus spp. grew on 500 (70%) [410 (57%) Aspergillus niger SC; 120 (17%) Aspergillus terreus SC; 101 (14%) A. fumigatus SC; 34 (5%) Aspergillus flavus SC]. The mean ± SD soil load of Aspergillus spp. was 2.23 ±âŸ0.41 log10 cfu/g (no differences among species). No azole-resistant non-A. fumigatus spp. isolate was detected. Itraconazole, voriconazole, isavuconazole and posaconazole MIC50/MIC90 (MIC range) of A. fumigatus SC strains were 0.25/0.5 (0.25 to >8), 0.5/1 (0.25 to >8), 1/1 (0.125 to >8) and 0.06/0.125 (0.06-1) mg/L, respectively. Overall, 1/500 (0.2%) of Aspergillus isolates, and 1/101 (1%) of A. fumigatus SC isolates, was pan-azole-resistant (itraconazole, voriconazole, isavuconazole and posaconazole MIC >8, >8, >8 and 1 mg/L, respectively). The resistant isolate was recovered from organically grown raisin grapes treated with homemade compost and it was an A. fumigatus sensu stricto isolate harbouring the TR46/Y121F/T289A mutation. The soil's load was higher compared with azole-susceptible strains (3.74 versus 2.09 log10 cfu/g). CONCLUSIONS: This is the first known report of environmental pan-azole-resistant A. fumigatus in Greece. Since data on Greek clinical isolates are lacking, this finding must alarm the systematic local surveillance of AR in medical settings.

In vitro activity of olorofim against clinical isolates of Scedosporium species and Lomentospora prolificans using EUCAST and CLSI methodologies.

OBJECTIVES: To evaluate the in vitro activity of olorofim, a new broad-spectrum antifungal with a novel mechanism of action, against a collection of 123 Spanish clinical isolates belonging to five Scedosporium species and Lomentospora prolificans. METHODS: The activity of olorofim against Scedosporium apiospermum (n = 30), Scedosporium boydii (n = 30), Scedosporium ellipsoideum (n = 10), Scedosporium aurantiacum (n = 20), Scedosporium dehoogii (n = 3) and Lomentospora prolificans (n = 30) was compared with that of amphotericin B, voriconazole, isavuconazole and micafungin by performing EUCAST and CLSI reference methods for antifungal susceptibility testing. RESULTS: Amphotericin B and isavuconazole showed MICs ≥2 mg/L for all the species evaluated and voriconazole was moderately active (GM, MIC50 and MIC90 values ≤2 mg/L) against all of them except L. prolificans. Micafungin was effective against S. apiospermum complex strains, but exhibited elevated MECs for S. dehoogii and S. aurantiacum. Olorofim showed low MICs for all the Scedosporium strains tested (GM values were lower than 0.130 and 0.339 by the EUCAST method and the CLSI method, respectively, for all of the species), including those belonging to the MDR species L. prolificans, for which GM values were 0.115 and 0.225 mg/L by the EUCAST method and the CLSI method, respectively, while the GMs for the rest of the antifungals evaluated were higher than 3.732 mg/L using both methodologies. CONCLUSIONS: Olorofim displayed promising in vitro activity against the Scedosporium and L. prolificans strains tested, some of which have reduced susceptibility to the antifungals that are currently in use.

Genomic and Phenotypic Heterogeneity of Clinical Isolates of the Human Pathogens Aspergillus fumigatus, Aspergillus lentulus, and Aspergillus fumigatiaffinis.

Fungal pathogens are a global threat to human health. For example, fungi from the genus Aspergillus cause a spectrum of diseases collectively known as aspergillosis. Most of the >200,000 life-threatening aspergillosis infections per year worldwide are caused by Aspergillus fumigatus. Recently, molecular typing techniques have revealed that aspergillosis can also be caused by organisms that are phenotypically similar to A. fumigatus but genetically distinct, such as Aspergillus lentulus and Aspergillus fumigatiaffinis. Importantly, some of these so-called cryptic species are thought to exhibit different virulence and drug susceptibility profiles than A. fumigatus, however, our understanding of their biology and pathogenic potential has been stymied by the lack of genome sequences and phenotypic profiling of multiple clinical strains. To fill this gap, we phenotypically characterized the virulence and drug susceptibility of 15 clinical strains of A. fumigatus, A. lentulus, and A. fumigatiaffinis from Spain and sequenced their genomes. We found heterogeneity in drug susceptibility across species and strains. We further found heterogeneity in virulence within each species but no significant differences in the virulence profiles between the three species. Genes known to influence drug susceptibility (cyp51A and fks1) vary in paralog number and sequence among these species and strains and correlate with differences in drug susceptibility. Similarly, genes known to be important for virulence in A. fumigatus showed variability in number of paralogs across strains and across species. Characterization of the genomic similarities and differences of clinical strains of A. lentulus, A. fumigatiaffinis, and A. fumigatus that vary in disease-relevant traits will advance our understanding of the variance in pathogenicity between Aspergillus species and strains that are collectively responsible for the vast majority of aspergillosis infections in humans.

Emerging mould infections: Get prepared to meet unexpected fungi in your patient.

Invasive fungal diseases are increasing issues in modern medicine, where the human immunodeficiency virus (HIV) pandemic and the wider use of immunosuppressive drugs generate an ever-growing number of immunocompromised patients with an increased susceptibility to uncommon fungal pathogens. In the past decade, new species have been reported as being responsible for disseminated and invasive fungal diseases in humans. Among them, the following genera are rare but seem emerging issues: Scopulariopsis, Hormographiella, Emergomyces, Westerdykella, Trametes, Actinomucor, Saksenaea, Apophysomyces, and Rhytidhysteron. Delay in diagnosis, which is often the case in these infections, jeopardizes patients' prognosis and leads to increased mortality. Here we summarize the clinical and biological presentation and the key features to identify these emerging pathogens and we discuss the available antifungal classes to treat them. We focused on Pubmed to recover extensively reported human invasive cases and articles regarding the nine previously cited fungal organisms. Information concerning patient background, macroscopic and microscopic description and pictures of these fungal organisms, histological features in tissues, findings with commonly used antigen tests in practice, and hints on potential efficient antifungal classes were gathered. This review's purpose is to help clinical microbiologists and physicians to suspect, identify, diagnose, and treat newly encountered fungi in hospital settings.

Genetic diversity and antifungal susceptibility patterns of Aspergillus nidulans complex obtained from clinical and environmental sources.

The molecular epidemiology and antifungal susceptibility of Aspergillus nidulans species complex has not been well studied. To evaluate the genetic diversity and antifungal susceptibility patterns of clinical and environmental isolates of A. nidulans complex. Sixty clinical and environmental isolates of Aspergillus section Nidulantes were collected from five countries (Iran, The Netherlands, Spain, Portugal and Greece). The species were molecularly identified by sequencing of ß-tubulin gene. The genetic diversity of A nidulans complex isolates (n = 54) was determined with a microsatellite genotyping assay. Antifungal susceptibility profile was determined using EUCAST method. The isolates were classified as A nidulans (46.7%), A spinulosporus (26.6%), A quadrilineatus (10%), A pachycristatus (3.3%), A rugulosus (3.3%), A unguis (5%), A creber, (1.7%), A olivicola (1.7%) and A sydowii (1.7%). Thirty-four sequence types (STs) were identified among the 54 A nidulans complex isolates. A high level of genetic diversity was found among A nidulans sensu stricto strains but low diversity was found among A spinulosporus strains. Amphotericin B showed high MICs to all species. The most active azole was posaconazole (GM = 0.64 mg/L), while itraconazole showed the highest MICs among azoles (GM = 2.95 mg/L). A spinulosporus showed higher MICs than A nidulans sensu stricto for all antifungals except for micafungin and anidulafungin. Interspecies variations may result in differences in antifungal susceptibility patterns and challenge antifungal therapy in infections caused by A nidulans. Differences in the distribution of STs or persistence of multiple STs might be related to the sources of isolation and niche specialisation.

Molecular Identification, Antifungal Susceptibility Testing, and Mechanisms of Azole Resistance in Aspergillus Species Received within a Surveillance Program on Antifungal Resistance in Spain.

Antifungal resistance is one of the major causes of the increasing mortality rates for fungal infections, especially for those caused by Aspergillus spp. A surveillance program was established in 2014 in the Spanish National Center for Microbiology for tracking resistance in the most prevalent Aspergillus species. A total of 273 samples were included in the study and were initially classified as susceptible or resistant according to EUCAST breakpoints. Several Aspergillus cryptic species were found within the molecularly identified isolates. Cyp51 mutations were characterized for Aspergillus fumigatus, Aspergillus terreus, and Aspergillus flavussensu stricto strains that were classified as resistant. Three A. fumigatus sensu stricto strains carried the TR34/L98H resistance mechanism, while two harbored G54R substitution and one harbored the TR46/Y121F/T289A mechanism. Seventeen strains had no mutations in cyp51A, with ten of them resistant only to isavuconazole. Three A. terreussensu stricto strains harbored D344N substitution in cyp51A, one of them combined with M217I, and another carried an A249G novel mutation. Itraconazole-resistant A. flavussensu stricto strains harbored P220L and H349R alterations in cyp51A and cyp51C, respectively, that need further investigation on their implication in azole resistance.

Clinical and Laboratory Development of Echinocandin Resistance in Candida glabrata: Molecular Characterization.

The pathogenic yeast Candida glabrata has become a public health issue due to the increasing number of echinocandin resistant clinical strains reported. In this study, acquisition and development of resistance to this antifungal class were studied in serial C. glabrata isolates from five patients admitted in two Spanish hospitals with a resistant profile against echinocandins associated with different mutations in hot-spot 1 of FKS2 gene. For two of these patients susceptible FKS wild-type isolates obtained prior to resistant ones were also investigated. Isolates were genotyped using multilocus sequence typing and microsatellite length polymorphism techniques, which yielded comparable results. Susceptible and resistant isolates from the same patient had the same genotype, being sequence type (ST) 3 the most prevalent among them. Isolates with different FKS mutations but the same ST were present in the same patient. MSH2 gene alterations were also studied to investigate their correlation with antifungal resistance acquisition but no association was found with antifungal resistance nor with specific genotypes. In vitro exposure to increasing concentrations of micafungin to susceptible isolates developed colonies carrying FKS mutations in agar plates containing a minimum concentration of 0.06 mg/L of micafungin after less than 48 h of exposure. We investigated the correlation between development of resistance and genotype in a set of susceptible strains after being in vitro exposed to micafungin and anidulafungin but no correlation was found. Mutant prevention concentration values and spontaneous growth frequencies after selection with both echinocandins were statistically similar, although FKS mutant colonies were more abundant after micafungin exposure (p < 0.001). Mutation S663P and F659 deletion were the most common ones found after selection with both echinocandins.

Diversity of coelomycetous fungi in human infections: A 10-y experience of two European reference centres.

The coelomycetous fungi are difficult to properly identify from their phenotypic characterization and their role as etiologic agents of human infections is not clear. We studied the species distribution of these fungi among clinical isolates that had been collected and stored over a ten-year period in two European reference laboratories (France and Spain). We identified phenotypically and molecularly 97 isolates by sequencing the D1-D2 fragment of the 28S nrRNA (LSU) gene and we provided the in vitro antifungal susceptibility pattern of seven antifungals against 46 isolates. Species of the orders Pleosporales and Glomerellales were present in both collections, and Botryosphaeriales and Diaporthales only in the French one. The most prevalent species were Medicopsis romeroi, Neocucurbitaria keratinophila, Neocucurbitaria unguis-hominis and Paraconiothyrium cyclothyrioides, which had been recovered primarily from superficial tissues. The Didymellaceae was the most common family represented, with 27 isolates distributed into five genera. Most of the isolates tested were susceptible to antifungals, and only the geometric mean (GM) and minimal inhibitory concentration (MIC) values of itraconazole and caspofungin had higher values. This study provides a good picture of the great diversity of coelomycetous fungi in the European clinical context, and the basis for future studies on this interesting but neglected group of fungi.

In vitro activity of olorofim (F901318) against clinical isolates of cryptic species of Aspergillus by EUCAST and CLSI methodologies.

OBJECTIVES: To investigate the in vitro activity of olorofim (F901318), a novel broad-spectrum antifungal agent, against 150 strains belonging to 16 different cryptic species of Aspergillus by EUCAST and CLSI methodologies. METHODS: Olorofim, amphotericin B, micafungin, posaconazole and voriconazole were tested against cryptic species belonging to Aspergillus fumigatus complex (n = 57), Aspergillus ustus complex (n = 25), Aspergillus niger complex (n = 20), Aspergillus flavus complex (n = 20), Aspergillus circumdati complex (n = 15) and Aspergillus terreus complex (n = 13) using EUCAST and CLSI methodologies for broth microdilution susceptibility testing of antifungal agents. RESULTS: Olorofim was the only drug with activity against all cryptic species of Aspergillus tested, including the multiresistant species Aspergillus lentulus, Aspergillus fumigatiaffinis and Aspergillus calidoustus. Geometric means of MICs for olorofim were lower (0.017, 0.015 and 0.098 mg/L, respectively, for EUCAST; and 0.015, 0.015 and 0.048 mg/L, respectively, for CLSI) than for amphotericin B (4.438, 12.699 and 0.554 mg/L, respectively, for EUCAST; and 0.758, 1.320 and 0.447 mg/L, respectively, for CLSI), voriconazole (2.549, 2.297 and 5.856 mg/L, respectively, for EUCAST; and 2.071, 1.741 and 5.657 mg/L, respectively, for CLSI) and posaconazole (0.307, 0.308 and 12.996 mg/L, respectively, for EUCAST; and 0.391, 0.215 and 9.514 mg/L, respectively, for CLSI). CONCLUSIONS: Olorofim shows encouraging in vitro activity against cryptic species of Aspergillus that can be hard to treat with current antifungal therapies. Further studies are warranted in order to assess its efficacy.

In vitro activity of APX001A against rare moulds using EUCAST and CLSI methodologies.

BACKGROUND: APX001A (E1210) is a novel broad-spectrum antifungal agent that inhibits Gwt1p, a protein that plays an important role in fungal cell wall integrity. Previous studies have shown that APX001A has broad activity against most species of Candida, Aspergillus, Scedosporium, Fusarium and Mucorales. OBJECTIVES: To investigate the in vitro activity of APX001A against 200 isolates belonging to 20 different species of Fusarium, Scedosporium, Lomentospora, Alternaria, cryptic species of Aspergillus and Mucorales. METHODS: APX001A and comparators were tested using EUCAST and CLSI methodologies for broth microdilution susceptibility testing of antifungal agents. RESULTS: APX001A was generally inactive against Mucorales, but active against all cryptic species of Aspergillus and Scedosporium/Lomentospora species. CONCLUSIONS: APX001A shows encouraging in vitro activity against some emerging fungi that are hard to treat with currently available antifungals.

Neocucurbitaria keratinophila: An emerging opportunistic fungus causing superficial mycosis in Spain.

Although there have been few reports of opportunistic infections (superficial and systemic) caused by coelomycetous fungi, they are becoming more frequent. Neocucurbitaria keratinophila (formerly Pyrenochaeta keratinophila), characterized by producing pycnidial conidiomata and small hyaline conidia, seems to be an emergent opportunistic pathogen in Spain. Since this fungus was first reported from human keratitis, eight strains have been isolates from clinical cases in Spain. This is a retrospective study of these fungal strains, including phenotypic and molecular characterizations, and in vitro antifungal susceptibility assays. These clinical strains were identified by sequencing four phylogenetic markers such as the internal transcribed spacer region (ITS1-5.8S-ITS2) and fragments of the 28S nrRNA (LSU), beta-tubulin (tub2), and RNA polymerase II subunit 2 (rpb2) genes, and by morphological characterization. All the strains tested were susceptible to the majority of antifungals, being isavuconazole the only drug that showed a poor antifungal activity.

Molecular Identification and Susceptibility Testing of Molds Isolated in a Prospective Surveillance of Triazole Resistance in Spain (FILPOP2 Study).

Antifungal resistance is increasing by the emergence of intrinsically resistant species and by the development of secondary resistance in susceptible species. A previous study performed in Spain revealed levels of azole resistance in molds of between 10 and 12.7%, but secondary resistance in Aspergillus fumigatus was not detected. We used itraconazole (ITZ)-supplemented medium to select resistant strains. A total of 500 plates supplemented with 2 mg/liter of ITZ were sent to 10 Spanish tertiary hospitals, and molecular identification and antifungal susceptibility testing were performed. In addition, the cyp51A gene in those A. fumigatus strains showing azole resistance was sequenced. A total of 493 isolates were included in the study. Sixteen strains were isolated from patients with an infection classified as proven, 104 were isolated from patients with an infection classified as probable, and 373 were isolated from patients with an infection classified as colonization. Aspergillus was the most frequent genus isolated, at 80.3%, followed by Scedosporium-Lomentospora (7.9%), Penicillium-Talaromyces (4.5%), Fusarium (2.6%), and the order Mucorales (1%). Antifungal resistance was detected in Scedosporium-Lomentospora species, Fusarium, Talaromyces, and Mucorales Three strains of A. fumigatus sensu stricto were resistant to azoles; two of them harbored the TR34+L98H mechanism of resistance, and the other one had no mutations in cyp51A The level of azole resistance in A. fumigatus remains low, but cryptic species represent over 10% of the isolates and have a broader but overall higher range of antifungal resistance.

Triazole Resistance in Aspergillus spp.: A Worldwide Problem?

Since the first description of an azole-resistant A. fumigatus strain in 1997, there has been an increasing number of papers describing the emergence of azole resistance. Firstly reported in the USA and soon after in Europe, it has now been described worldwide, challenging the management of human aspergillosis. The main mechanism of resistance is the modification of the azole target enzyme: 14-α sterol demethylase, encoded by the cyp51A gene; although recently, other resistance mechanisms have also been implicated. In addition, a shift in the epidemiology has been noted with other Aspergillus species (mostly azole resistant) increasingly being reported as causative agents of human disease. This paper reviews the current situation of Aspergillus azole resistance and its implications in the clinical setting.