In vitro antifungal activity of amphotericin B and 11 comparators against Aspergillus terreus species complex

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.

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.

Five-year surveillance study of clinical and environmental Triazole-Resistant Aspergillus fumigatus isolates in Iran

BACKGROUND

Invasive aspergillosis is one of the most common fungal infections and azole resistance in Aspergillus fumigatus (ARAf) is a growing medical concern in high-risk patients. To our knowledge, there is no comprehensive epidemiological surveillance study on the prevalence and incidence of ARAf isolates available in Iran.

OBJECTIVES

The study aimed to report a five-year survey of triazole phenotypes and genotype patterns concerning the resistance in clinical and environmental A. fumigatus in Iran.

METHODS

During the study time frame (2016-2021), a total of 1208 clinical and environmental Aspergillus species were collected. Isolates were examined and characterised by in vitro antifungal susceptibility testing (CLSI M38 broth microdilution) and cyp51A sequencing.

RESULTS

In total, 485 Aspergillus section Fumigati strains were recovered (clinical, n = 23; 4.74% and environment, n = 462; 95.26%). Of which A. fumigatus isolates were the most prevalent species (n = 483; 99.59%). Amphotericin B and the echinocandins demonstrated good in vitro activity against the majority of isolates in comparison to triazole. Overall, 16.15% (n = 78) of isolates were phenotypically resistant to at least one of the azoles. However, 9.73% of A. fumigatus isolates for voriconazole were classified as resistant, 89.03% were susceptible, and 1.24% were intermediate. While, for itraconazole and posaconazole, using the epidemiological cut-off value 16.15% and 6.83% of isolates were non-wild types, respectively. Remarkably, in 21.79% (n = 17) phenotypically resistant isolates, no mutations were detected within the cyp51A gene.

CONCLUSION

Although the incidence of ARAf varies from country to country, in Iran the rate has ranged from 3.3% to 18%, significantly increasing from 2013 to 2021. Strikingly, a quarter of the phenotypically resistant isolates harboured no mutations in the cyp51A gene. It seems that other mechanisms of resistance are importantly increasing. To fill a gap in our understanding of the mechanism for azole resistance in the non-cyp51A strains, we highly recommend further and more extensive monitoring of the soil with or without exposure to fungicides in agricultural and hospital areas.

Lipid-Like Biofilm from a Clinical Brain Isolate of Aspergillus terreus: Quantification, Structural Characterization and Stages of the Formation Cycle

Invasive infections caused by filamentous fungi have increased considerably due to the alteration of the host's immune response. Aspergillus terreus is considered an emerging pathogen and has shown resistance to amphotericin B treatment, resulting in high mortality. The development of fungal biofilm is a virulence factor, and it has been described in some cases of invasive aspergillosis. In addition, although the general composition of fungal biofilms is known, findings related to biofilms of a lipid nature are rarely reported. In this study, we present the identification of a clinical strain of A. terreus by microbiological and molecular tools, also its in vitro biofilm development capacity: (i) Biofilm formation was quantified by Crystal Violet and reduction of tetrazolium salts assays, and simultaneously the stages of biofilm development were described by Scanning Electron Microscopy in High Resolution (SEM-HR). (ii) Characterization of the organizational structure of the biofilm was performed by SEM-HR. The hyphal networks developed on the surface, the abundant air channels created between the ECM (extracellular matrix) and the hyphae fused in anastomosis were described. Also, the presence of microhyphae is reported. (iii) The chemical composition of the ECM was analyzed by SEM-HR and CLSM (Confocal Laser Scanning Microscopy). Proteins, carbohydrates, nucleic acids and a relevant presence of lipid components were identified. Some structures of apparent waxy appearance were highlighted by SEM-HR and backscatter-electron diffraction, for which CLSM was previously performed. To our knowledge, this work is the first description of a lipid-type biofilm in filamentous fungi, specifically of the species A. terreus from a clinical isolate.

Trends in the Prevalence of Amphotericin B-Resistance (AmBR) among Clinical Isolates of Aspergillus Species

The challenges of the invasive infections caused by the resistant Aspergillus species include the limited access to antifungals for treatment and high mortality. This study aimed to provide a global perspective of the prevalence of amphotericin B resistance (AmBR), geographic distribution, and the trend of AmBR from 2010 to 2020. To analyze the prevalence of in vitro AmBR in clinical Aspergillus species, we reviewed the literature and identified a total of 72 articles. AmBR was observed in 1128 out of 3061 Aspergillus terreus (36.8%), 538 out of 3663 Aspergillus flavus (14.9%), 141 out of 2691 Aspergillus niger (5.2%), and 353 out of 17,494 Aspergillus fumigatus isolates (2.01%). An increasing trend in AmB-resistant isolates of A. fumigatus and a decreasing trend in AmB-resistant A. terreus and A. flavus isolates were observed between 2016 and 2020. AmB-resistant A. terreus and A. niger isolates, accounting for 40.4% and 20.9%, respectively, were the common AmB-resistant Aspergillus species in Asian studies. However, common AmB-resistant Aspergillus species reported by European and American studies were A. terreus and A. flavus isolates, accounting for 40.1% and 14.3% in 31 studies from Europe and 25.1% and 11.7% in 14 studies from America, respectively. The prevalence of AmB-resistant A. niger in Asian isolates was higher than in American and European. We found a low prevalence of A. terreus in American isolates (25.1%) compared to Asian (40.4%) and European (40.1%). Future studies should focus on analyzing the trend of AmBR on a regional basis and using the same methodologies.

Multicenter Study of Susceptibility of Aspergillus Species Isolated from Iranian University Hospitals to Seven Antifungal Agents

Aspergillus species are a major cause of life-threatening invasive infections and noninvasive diseases. This study seeks to investigate the frequency of Aspergillus species among Iranian patients and their susceptibility to seven antifungals. In a cross-sectional study, 233 Aspergillus isolates were collected from 11 university hospitals in Iran between 2018 and 2021. Aspergillus isolates were identified based on colony morphology, microscopic characteristics, PCR-restriction fragment length polymorphism (RFLP), and sequencing of the beta-tubulin gene. The CLSI M38-A2 reference methodology was used for antifungal susceptibility testing of amphotericin B, voriconazole, posaconazole, itraconazole, luliconazole, isavuconazole, and caspofungin. Members of Aspergillus section Flavi (117/233, 50.2%), Aspergillus section Nigri (77/233, 33.1%), Aspergillus section Fumigati (21/233, 9%), Aspergillus section Terrei (14/233, 6%), Aspergillus pseudodeflectus (2/233, 0.85%), and Aspergillus melleus (2/233, 0.85%) were isolated from the samples. The lowest 0.25 MIC90 values for all isolates tested were for luliconazole (0.016 μg/mL) and isavuconazole (0.250 μg/mL), and the highest value was observed for itraconazole (≥ 8μg/mL). The 90% minimum effective concentration (MEC90) value for caspofungin was 0.125 μg/mL. MIC90 values for voriconazole, amphotericin B, and posaconazole were 1, 2, and 2 μg/mL, respectively. The non-wild-type species were presented for amphotericin B (3%), voriconazole (1.3%), posaconazole (2.6%), luliconazole (1.3%), isavuconazole (1.7%), and caspofungin (4.7%). Positive correlations in the MIC values of azole antifungals were observed, and using one azole increases the MIC value rates of other ones. None of the species were pan-azole resistant. Species of Aspergillus section Flavi were the most common Aspergillus species isolated from Iranian samples. Luliconazole, caspofungin, and isavuconazole present the most effective antifungal agents for treatment of infection due to Aspergillus species. Susceptibility tests should be performed frequently in each region for the best management of patients. IMPORTANCE Aspergillus species are the leading cause of invasive aspergillosis in immunocompromised hosts. The susceptibility of Aspergillus species to antifungal agents might be different. Azole-resistant species have emerged worldwide. Performing susceptibility testing in each region can help in the best management of patients. Here, we show the epidemiology and distribution of Aspergillus species in Iran and their susceptibility patterns for seven antifungal agents. The significant points of the present study are that species of Aspergillus section Flavi are the most prevalent Aspergillus species isolated from 11 university hospitals. Luliconazole, caspofungin, and isavuconazole were effective antifungal agents against all Aspergillus species.

Luliconazole Nail Lacquer for the Treatment of Onychomycosis: Formulation, Characterization and In Vitro and Ex Vivo Evaluation

Onychomycosis is the most common fungal infection of the nail affecting the skin under the fingertips and the toes. Currently, available therapy for onychomycosis includes oral and topical therapies, either alone or in combination. Oral antifungal medication has been associated with poor drug bioavailability and potential gastrointestinal and systemic side effects. The objective of this study was to prepare and evaluate the luliconazole nail lacquer (LCZ-NL) for the effective treatment of onychomycosis. In the current work, LCZ-NL was formulated in combination with penetration enhancers to overcome poor penetration. A 3² full factorial formulation design of experiment (DOE) was applied for optimization of batches with consideration of dependent (drying time, viscosity, and rate of drug diffusion) and independent (solvent ratio and film former ratio) variables. The optimized formulation was selected based on drying time, viscosity, and rate of drug diffusion. The optimized formulation was further evaluated for % non-volatile content assay, smoothness of flow, water resistance, drug content, scanning electron microscope (SEM), atomic force microscope (AFM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), in vitro drug release, ex vivo transungual permeation, antifungal efficacy, and stability study. The optimized LCZ-NL contained 70:30 solvent ratio and 1:1 film former ratio and was found to have ~ 1.79-fold higher rate of drug diffusion in comparison with LULY™. DSC and XRD studies confirmed that luliconazole retains its crystalline property in the prepared formulation. Antifungal study against Trichophyton spp. showed that LCZ-NL has comparatively higher growth inhibition than LULY™. Hence, developed LCZ-NL can be a promising topical drug delivery system for treating onychomycosis.

Aspergillus terreus and the Interplay with Amphotericin B: from Resistance to Tolerance?

Aspergillus terreus is an opportunistic causative agent of invasive aspergillosis and, in most cases, it is refractory to amphotericin B (AMB) therapy. Notably, AMB-susceptible Aspergillus terreus sensu stricto (s.s.) representatives exist which are also associated with poor clinical outcomes. Such findings may be attributable to drug tolerance, which is not detectable by antifungal susceptibility testing. Here, we tested in vitro antifungal susceptibility (AFST) and the fungicidal activity of AMB against 100 clinical isolates of A. terreus species complex in RPMI 1640 and antibiotic medium 3 (AM3). MICs ranged from 0.5 to 16 μg/mL for RPMI 1640 and from 1 to >16 mg/L for AM3. AMB showed medium-dependent activity, with fungicidal effects only in antibiotic medium 3, not in RPMI 1640. Furthermore, the presence of AMB-tolerant phenotypes of A. terreus has been examined by assessing the minimum duration for killing 99% of the population (MDK99) and evaluating the data obtained in a Galleria mellonella infection model. A time-kill curve analysis revealed that A. terreus with AMB MICs of ≤1 mg/L (susceptible range) displayed AMB-tolerant phenotypes, exhibiting MDK99s at 18 and 36 h, respectively. Survival rates of infected G. mellonella highlighted that AMB was effective against susceptible A. terreus isolates, but not against tolerant or resistant isolates. Our analysis reveals that A. terreus isolates which are defined as susceptible based on MIC may comprise tolerant phenotypes, which may, in turn, explain the worse outcome of AMB therapy for phenotypically susceptible isolates.

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.

The Elevated Endogenous Reactive Oxygen Species Contribute to the Sensitivity of the Amphotericin B-Resistant Isolate of Aspergillus flavus to Triazoles and Echinocandins

Aspergillus flavus has been frequently reported as the second cause of invasive aspergillosis (IA), as well as the leading cause in certain tropical countries. Amphotericin B (AMB) is a clinically important therapy option for a range of invasive fungal infections including invasive aspergillosis, and in vitro resistance to AMB was associated with poor outcomes in IA patients treated with AMB. Compared with the AMB-susceptible isolates of A. terreus, the AMB-resistant isolates of A. terreus showed a lower level of AMB-induced endogenous reactive oxygen species (ROS), which was an important cause of AMB resistance. In this study, we obtained one AMB-resistant isolate of A. flavus, with an AMB MIC of 32 μg/mL, which was sensitive to triazoles and echinocandins. This isolate presented elevated endogenous ROS levels, which strongly suggested that no contribution of decreased AMB-induced endogenous ROS for AMB-resistance, opposite to those observed in A. terreus. Further, we confirmed that the elevated endogenous ROS contributed to the sensitivity of the AMB-resistant A. flavus isolate to triazoles and echinocandins. Further investigation is needed to elucidate the causes of elevated endogenous ROS and the resistance mechanism to AMB in A. flavus.

Molecular Diversity of Aspergilli in Two Iranian Hospitals

The Aspergillus species are main causative agents of various infections such as invasive aspergillosis (IA) in immunocompromised patients and these infections have high mortality rates. In this study, we provide insight in the species causing aspergillosis in Iran based on morphology and sequence data. Clinical (n = 117) and environmental isolates (n = 54) collected during 2010-2016 from University hospitals in Mashhad and Tehran (Iran) were identified both morphologically and molecularly using partial calmodulin (CaM) gene sequences. Clinical cases were identified based on EORTC/MSG criteria. Aspergillus flavus (n = 96, 55%) was the most prevalent species among the clinical and environmental isolates while A. fumigatus (n = 13, 7.5%) ranked fourth after A. tubingensis (n = 23, 13%) and A. welwitchiae (n = 18, 10%). Species such as A. tubingensis, A. welwitschiae, A. fumigatus, A. sydowii, A. neoniger and A. terreus were present in both clinical and environmental samples indicating the possible environmental source of infections. Interestingly, A. niger was isolated only once. Furthermore, 13 other rare and cryptic Aspergillus species were detected. Pulmonary and respiratory disorders (n = 33), followed by transplantation (n = 23), invasive fungal rhinosinusitis (n = 14), and haematological malignancies (n = 12) were major predisposing factors. According to EORTC/MSG criteria, there were 43 probable cases identified followed by 36 cases for each of proven and possible ones. Correct molecular identification will be useful for further epidemiological studies.

Aspergillus collected in specific indoor settings: their molecular identification and susceptibility pattern

Exposure to Aspergillus conidia is an increased risk factor for the development of respiratory symptoms. The emergence of azole resistance in Aspergillus fumigatus is a major concern for the scientific community. The aim of this study was to perform the molecular identification of Aspergillus species collected from different occupational and non-occupational indoor settings and to study the azole susceptibility profile of the collected Fumigati isolates. The selected Aspergillus isolates were identified as belonging to the sections Fumigati, Nigri Versicolores, Terrei, Clavati and Nidulantes. All the Aspergillus fumigatus were screened for azole resistance using an agar media supplemented with itraconazole, voriconazole and posaconazole. None of the tested isolates showed resistance to those azoles. Knowledge of Aspergillus epidemiology in specific indoor environments allows a better risk characterization regarding Aspergillus burden. This study allowed the analysis of the molecular epidemiology and the determination of the susceptibility pattern of Aspergillus section Fumigati found in the studied indoor settings.

Potent in vitro activity of curcumin and quercetin co-encapsulated in nanovesicles without hyaluronan against Aspergillus and Candida isolates

The rapid emergence of resistance to classical antifungals has increased the interest in novel antifungal compounds. Curcumin and quercetin are two natural plant-derived bioactive molecules shown to promote wound healing in injured tissues. In this study, we investigated the in vitro susceptibility of several Aspergillus and Candida isolates to curcumin and quercetin encapsulated in nanovesicles with and without hyaluronan and elucidated the efficacy of these nanovesicles as topical drug delivery systems. Antifungal susceptibility testing performed according to the CLSI guidelines indicated that curcumin-quercetin co-encapsulated in nanovesicles without hyaluronan (CUR-QUE-NV-WH) had stronger activity against Candida isolates than fluconazole. Furthermore, CUR-QUE-NV-WH showed efficacy against fluconazole-resistant Candida isolates as evidenced by MICs at least two times lower than those of fluconazole. Examination of skin permeation profiles using an in vitro Franz diffusion cell system revealed that curcumin and quercetin delivered by nanovesicles were released and accumulated in the skin; however, only quercetin could penetrate through the skin layers. Collectively, our results demonstrate that CUR-QUE-NV-WH has potent antifungal activity against Candida isolates and might be a topical treatment, which warrants its further investigation as a novel antifungal agent.

Molecular identification, phylogenetic analysis and antifungal susceptibility patterns of Aspergillusnidulans complex and Aspergillusterreus complex isolated from clinical specimens

OBJECTIVE

Aspergillus sections Terrei and Nidulantes are the less common causes of invasive aspergillosis and pulmonary aspergillosis (PA) in immunocompromised patients when compared to A. fumigatus and A. flavus. Identifying these fungi as the infectious agent is crucial because of the resistance to amphotericin B (AMB) and increased lethality. The aim of this study was to identify the molecular status, evaluate the genetic diversity and examine the antifungal susceptibility profile of the uncommon Aspergillus species. Forty-five uncommon Aspergillus species were identified based on the microscopic and macroscopic criteria. Then, the molecular identification was performed using the sequencing beta tubulin (benA) gene. In vitro antifungal susceptibility to amphotericin B (AMB), itraconazole (ITC), ravuconazole (RAV), voriconazole (VRC), caspofungin (CFG) isavuconazole (ISA) and posaconazole (POS) test was performed according to the CLSI M38-A2 guidelines.

RESULTS

A. terreus was the most species detected, followed by A. nidulans, A. latus, A.ochraceus, and A. citrinoterreus, respectively. The analysis of the benA gene showed the presence of 12 distinct genotypes among the A. terreus isolates. The other species did not show any intraspecies variation. CFG exhibited the lowest MEC₅₀/MIC₅₀ (0.007μg/mL), followed by POS (0.125μg/mL), VRC, ITC, ISA (0.25μg/mL), RAV (0.5μg/mL), and AMB (8μg/mL). Among all the isolates, only 15.5% (7/45) were susceptible to AMB.

CONCLUSION

Antifungal susceptibility pattern of the uncommon Aspergillus species is useful to improve patient management and increase knowledge concerning the local epidemiology. Moreover, this information is necessary when an outbreak dealing with drug-resistant infections occurs.

Antifungal Activity of a Novel Triazole, Efinaconazole and Nine Comparators against 354 Molecularly Identified Aspergillus Isolates

Management of superficial aspergillosis is a major challenge owing to the frequent relapses and treatment failure, which may pose a potential risk, thereby gradually developing resistant species. Therefore, necessitating the development of new antifungals with higher potency should be considered as alternative strategies for efficient management of infections. We aimed to investigate the susceptibility of Aspergillus isolates toward a novel triazole, efinaconazole, in comparison with various classes of antifungal drugs. Antifungal susceptibility testing was performed according to the Clinical and Laboratory Standards Institute M38-A2 guidelines. Efinaconazole exhibited poor activity against mutant A. fumigatus strains, A. niger sensu stricto, and A. tubingensis with GM MIC values of 3.62, 1.62, and 2 μg/ml, respectively; however, surprisingly, it efficiently inhibited the growth of A. terreus sensu stricto, followed by wild-type A. fumigatus and A. flavus with GM MIC values of 0.29, 0.42, and 0.52 μg/ml, respectively. Presumably, efinaconazole is inefficient in aspergillosis treatment due to the low susceptibility of A. niger sensu stricto, A. tubingensis, and mutant A. fumigatus; however, it may be effective in treating superficial aspergillosis caused by wild-type A. fumigatus, A. terreus sensu stricto, and A. flavus. Further studies are needed to determine how these findings may translate into in vivo efficacy.

Synergistic effects of vorinostat (SAHA) and azoles against Aspergillus species and their biofilms

BACKGROUND

Invasive aspergillosis is a fungal infection that occurs mainly in immunocompromised patients. It is responsible for a high degree of mortality and is invariably unresponsive to conventional antifungal treatments. Histone deacetylase inhibitors can affect the cell cycle, apoptosis and differentiation. The histone deacetylase inhibitor vorinostat (SAHA) has recently received approval for the treatment of cutaneous T cell lymphoma. Here, we investigated the interactions of SAHA and itraconazole, voriconazole, and posaconazole against Aspergillus spp. in vitro using both planktonic cells and biofilms.

RESULTS

We investigated 20 clinical strains using broth microdilution checkerboard methods. The results showed synergy between SAHA and itraconazole, voriconazole, and posaconazole against 60, 40, and 25% of tested isolates of planktonic Aspergillus spp., respectively. Similar synergy was also observed against Aspergillus biofilms. The expression of the azole-associated multidrug efflux pumps MDR1, MDR2, MDR3 and MDR4, as well as that of HSP90, was measured by RT-PCR. The results indicated that the molecular mechanism of the observed synergistic effects in Aspergillus fumigatus may be partly associated with dampened expression of the efflux pump genes and, furthermore, that HSP90 suppression may be a major contributor to the observed synergistic effects of the drugs.

CONCLUSIONS

SAHA has potential as a secondary treatment to enhance the effects of azoles against both biofilm and planktonic cells of Aspergillus spp. in vitro. This effect occurs mostly by inhibition of HSP90 expression.

MALDI-TOF MS for the rapid identification and drug susceptibility testing of filamentous fungi

The present study aimed to evaluate the applicability of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for identifying filamentous fungi and assessing the in vitro activities of common antifungal drugs against different kinds of filamentous fungi that are commonly encountered in a clinical setting. A total of 123 strains of filamentous fungi (24 species) were submitted for identification by MALDI-TOF MS, and the findings were compared with those obtained by conventional methods. The discrepancies were further investigated by internal transcribed spacer (ITS) sequence analysis. Then, 79 strains were randomly selected for further testing by the minimum inhibitory concentration Etest method. MALDI-TOF MS correctly identified 114 (92.70%) of the 123 filamentous fungi and failed to identify six isolates (4.9%). By contrast, the conventional identification methods made 113 (91.9%) correct identifications. In addition, 15 isolates of filamentous fungi were further identified by ribosomal DNA-ITS sequencing. In the in vitro antifungal susceptibility test, voriconazole showed the strongest antifungal activity among the tested drugs against a broad range of filamentous fungi. Caspofungin showed a better in vitro antifungal activity than fluconazole, itraconazole, and amphotericin B. MALDI-TOF MS offers a cost/time-saving, high-throughput and accurate working protocol for identifying filamentous fungi. Voriconazole could still serve as the first-line drug for treating serious infections caused by filamentous fungi, while caspofungin may be another treatment option for fungal infections.

The Emergence of Rare Clinical Aspergillus Species in Qatar: Molecular Characterization and Antifungal Susceptibility Profiles

Aspergillus are ubiquitous mold species that infect immunocompetent and immunocompromised patients. The symptoms are diverse and range from allergic reactions, bronchopulmonary infection, and bronchitis, to invasive aspergillosis. The aim of this study was to characterize 70 Aspergillus isolates recovered from clinical specimens of patients with various clinical conditions presented at Hamad general hospital in Doha, Qatar, by using molecular methods and to determine their in vitro antifungal susceptibility patterns using the Clinical and Laboratory Standards Institute (CLSI) M38-A2 reference method. Fourteen Aspergillus species were identified by sequencing β-tubulin and calmodulin genes, including 10 rare and cryptic species not commonly recovered from human clinical specimens. Aspergillus welwitschiae is reported in this study for the first time in patients with fungal rhinosinusitis (n = 6) and one patient with a lower respiratory infection. Moreover, Aspergillus pseudonomius is reported in a patient with fungal rhinosinusitis which is considered as the first report ever from clinical specimens. In addition, Aspergillus sublatus is reported for the first time in a patient with cystic fibrosis. In general, our Aspergillus strains exhibited low MIC values for most of the antifungal drugs tested. One strain of Aspergillus fumigatus showed high MECs for echinocandins and low MICs for the rest of the drugs tested. Another strain of A. fumigatus exhibited high MIC for itraconazole and categorized as non-wild type. These findings require further analysis of their molecular basis of resistance. In conclusion, reliable identification of Aspergillus species is achieved by using molecular sequencing, especially for the emerging rare and cryptic species. They are mostly indistinguishable by conventional methods and might exhibit variable antifungal susceptibility profiles. Moreover, investigation of the antifungal susceptibility patterns is necessary for improved antifungal therapy against aspergillosis.

Airway colonisation by Candida and Aspergillus species in Iranian cystic fibrosis patients

Cystic fibrosis (CF) is associated with increased rates of morbidity and mortality due to fungal and bacterial colonisation of the airways or respiratory infections. The prevalence of fungi in Iranian CF population has been underestimated. Therefore, the current study was conducted to define the frequency of fungi in respiratory specimens obtained from Iranian CF patients based on conventional and molecular assays. Furthermore, in vitro antifungal susceptibility testing was performed on the obtained isolates according to the guidelines from the Clinical and Laboratory Standards Institute. A cohort of 42 CF patients, including 29 males and 13 females, were categorised according to the referenced diagnostic criteria. Candida albicans (n = 24, 80%), C. dubliniensis (n = 2, 6.6%), C. parapsilosis (n = 2, 6.6%), C. tropicalis (n = 1, 3.3%), C. glabrata (n = 1, 3.3%) and Meyerozyma caribbica (n = 1, 3.3%) were isolated from 73.8% of the CF patients. Aspergillus terreus (n = 3, 42.8%) was identified as the most common Aspergillus species, followed by A. fumigatus (n = 2, 28.5%), A. oryzae (n = 1, 14.2%) and A. flavus (n = 1, 14.2%). Bacterial and fungal co-colonisation was detected in 7 (16.6%) and 22 (52.3%) samples that were positive for Aspergillus and Candida species, respectively. However, Scedosporium species and Exophiala dermatitidis never were detected. In terms of geometric mean (GM) minimum inhibitory concentrations (MICs), posaconazole (0.018 μg/mL) and caspofungin (0.083 μg/mL) exhibited the highest antifungal activities against all Candida species. In addition, posaconazole exhibited the lowest MIC range (0.008-0.063 μg/mL) against all Aspergillus species, followed by caspofungin (0.016-0.125 μg/mL) and voriconazole (0.125-0.25 μg/mL). To conclude, it is essential to adopt a consistent method for the implementation of primary diagnosis and determination of treatment regimen for the CF patients. However, further studies are still needed to better define the epidemiology of fungal organisms in CF patients from the Middle East and the clinical significance of their isolation.

Low In Vitro Antifungal Activity of Tavaborole against Yeasts and Molds from Onychomycosis

The in vitro activity of tavaborole, an FDA-approved antifungal drug, was compared to that of four antifungal agents against 170 clinical fungal isolates originating from patients with onychomycosis. Tavaborole had low activity against all isolates compared to itraconazole, terbinafine, and fluconazole, the principal choices for treatment of onychomycosis. Thus, it appears that tavaborole is not a candidate for the treatment of onychomycosis due to Candida species, Aspergillus species, and dermatophytes.

Potent Activities of Luliconazole, Lanoconazole, and Eight Comparators against Molecularly Characterized Fusarium Species

A collection of clinical (n = 47) and environmental (n = 79) Fusarium isolates were tested against 10 antifungal drugs, including 2 novel imidazoles. Luliconazole and lanoconazole demonstrated very low geometric mean MIC values of 0.005 and 0.013 μg/ml, respectively, compared with 0.51 μg/ml for micafungin, 0.85 μg/ml for efinaconazole, 1.12 μg/ml for natamycin, 1.18 μg/ml for anidulafungin, 1.31 μg/ml for voriconazole, 1.35 μg/ml for caspofungin, 1.9 μg/ml for amphotericin B, and 4.08 μg/ml for itraconazole. Results show that these drugs are potential candidates for (topical) treatment of skin and nail infections due to Fusarium species.