Trends in the activity of mold-active azole agents against Aspergillus fumigatus clinical isolates with and without cyp51 alterations from Europe and North America (2017-2021)

Invasive Aspergillosis in the Current Era

Despite significant advances, aspergillosis remains a critical health concern, with an evolving epidemiology and expanding populations of at-risk patients. Historically, fewer than 10 Aspergillus species were considered clinically significant. However, advancements in diagnostic technologies, such as DNA sequencing and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, have identified previously unrecognized "cryptic" Aspergillus species. This clinical review highlights the current epidemiology, risk factors, pathogenesis, clinical presentation, diagnosis, and invasive aspergillosis (IA) treatment. Diagnosing IA necessitates a multifaceted approach, integrating clinical evaluation, imaging studies, microbiological culture, serologic tests, and advanced molecular techniques.

Use of voriconazole to predict susceptibility and resistance to isavuconazole for Aspergillus fumigatus using CLSI methods and interpretive criteria

Aspergillus fumigatus is a common cause of pulmonary and invasive mold infections among immunocompromised hosts. Mortality in immunocompromised hosts with invasive Aspergillus infections (IAI) has been reported to be as high as 80%. Therefore, appropriate therapy is essential in treating IAI. Both isavuconazole and voriconazole are first-line agents in treatment guidelines for IAI, but isavuconazole has favorable properties, often leading it to be preferred over voriconazole, given the lengthy duration of treatment. It is difficult to perform mold antifungal susceptibility testing, which often requires a reference lab and several weeks to determine results. Therefore, use of surrogate markers can be helpful to infer susceptibility when testing is not possible or delayed. We performed isavuconazole and voriconazole broth microdilution susceptibility testing by the Clinical and Laboratory Standards Institute (CLSI) method on a collection of 976 non-duplicate A. fumigatus isolates from a global surveillance program between 2017 and 2022. We found that voriconazole and isavuconazole have a very high essential agreement within two doubling dilutions at 99.9% and a categorical agreement of 92.7% with no very major errors, one major error (0.11%), and <10% minor errors. Many of the minor errors were in the setting of voriconazole testing at a MIC of 0.5 mg/L (susceptible) but isavuconazole at 2 mg/L (intermediate). Genetic analysis of cyp51 genes confirmed that isavuconazole and voriconazole susceptibility testing identified isolates with cyp51A and cyp51B mutations. Voriconazole can be used to predict the isavuconazole susceptibility testing result when A. fumigatus is tested by CLSI broth microdilution methodology.

Comprehensive Review of Environmental Surveillance for Azole-Resistant Aspergillus fumigatus: A Practical Roadmap for Hospital Clinicians and Infection Control Teams

As azole-resistant Aspergillus fumigatus emerges globally, healthcare facilities face mounting challenges in managing invasive aspergillosis. This review synthesizes worldwide azole resistance data to reveal profound regional variability, demonstrating that findings from other regions cannot be directly extrapolated to local settings. Consequently, hospital-level environmental surveillance is crucial for tailoring interventions to local epidemiology and detecting resistant strains in real-time. We outline practical approaches-encompassing sampling site prioritization, diagnostic workflows (culture-based and molecular), and PDCA-driven continuous improvement-so that even resource-limited facilities can manage resistant isolates more effectively. By linking real-time surveillance findings with clinical decisions, hospitals can tailor antifungal stewardship programs and swiftly adjust prophylaxis or treatment regimens. Our approach aims to enable accurate, ongoing evaluations of emerging resistance patterns, ensuring that institutions maintain efficient and adaptive programs. Ultimately, we advocate for sustained, collaborative efforts worldwide, where facilities adapt protocols to local conditions, share data through international networks, and contribute to a global knowledge base on resistance mechanisms. Through consistent application of these recommendations, healthcare systems can better preserve azole efficacy, safeguard immunocompromised populations, and refine infection control practices in the face of evolving challenges.

Epidemiological characteristics of invasive Aspergillus isolates: Morphology, drug susceptibility, and mutations in azole drug targets

BACKGROUND

The global epidemiology of aspergillosis varies and is influenced by various factors. To elucidate the disease burden and identify effective control strategies, the epidemiological characteristics of Aspergillus infections have to be investigated. The aim of this study was to assess the epidemiological characteristics of various Aspergillus species, including their morphological features, species identification, and in vitro susceptibility to nine antifungal agents in a large tertiary hospital in northern China.

METHODS

Ninety-five clinical isolates of Aspergillus were collected from patients. Aspergillus species identification was performed using conventional morphological methods, MALDI-TOF MS, and gene sequencing. In vitro susceptibility to nine antifungal agents was evaluated using the Sensititre YeastOne system. Target genes (cyp51A and cyp51b) of A. tubinazole were sequenced using the Sanger method.

RESULTS

Aspergillus fumigatus, Aspergillus niger, Aspergillus flavus, Aspergillus tubingensis, and Aspergillus terreus were the most common isolated species. Rare species included Aspergillus tamarii, Aspergillus usamil, Aspergillus versicolor, Aspergillus udagawae, Aspergillus lentulus, Aspergillus sydowii, and Aspergillus quadrilineatus. Pulmonary infections accounted for 86.3 % (82/95) of collected cases, and the in-hospital mortality rate was 22.1 %. The median minimum inhibitory concentration (MIC) range of amphotericin B was 1.5-4 mg/L. The MIC range of triazoles against Aspergillus species, excluding Aspergillus udagawae and Aspergillus lentulus, was 0.12-0.5 mg/L. The median minimum effective concentration range of echinocandins was < 0.008-0.03 mg/L. Non-wild-type resistance to amphotericin B was observed in 29.6 % (16/54) of Aspergillus fumigatus isolates, and non-wild-type resistance to voriconazole was observed in 11.1 % (1/9) of Aspergillus tubingensis isolates. Moreover, CYP51A and CYP51b of Aspergillus tabinensis had 2-29 and 10-13 nucleotide mutations, respectively.

CONCLUSION

Patients with non- Aspergillus fumigatus infection accounted for 43.2 %. The T256A amino acid substitution in CYP51A of Aspergillus tabinensis did not lead to increased azole drug MICs.

Epidemiology and Antifungal Susceptibilities of Clinically Isolated Aspergillus Species in Tertiary Hospital of Southeast China

Background and Aim

Infection caused by Aspergillus species poses a growing global concern, yet their prevalence in Southeast China lacks comprehensive documentation. This retrospective analysis aims to elucidate the epidemiological role and antifungal susceptibilities of Aspergillus species at Huashan Hospital of Fudan University, Shanghai, China.

Methods

Data spanning from 2018 to 2022, encompassing demographic, clinical, and laboratory information on Aspergillus species isolates were analyzed. The isolates were subjected to susceptibility testing using YeastOneTM broth microdilution system.

Results

A total of 253 Aspergillus isolates were identified, with A. fumigatus (57.71%) being the predominant species, followed by A. niger (26.88%), A. flavus (10.67%), and A. terreus (3.95%). Notably, the highest number of isolates originated from the Department of Infectious Disease (28.06%), with sputum (54.94%) being the primary source of isolation, where A. fumigatus was the dominant species. Gastrointestinal disorder (23.90%), hepatic disorder (9.09%), and diabetes (8.30%) were identified as the most prevalent underlying conditions, with A. fumigatus being the most abundant species in each case, accounting for 65.08%, 82.60%, and 73.91%, respectively, followed by A. flavus. Non-wild-type (NWT) Aspergillus isolates exhibited higher resistance against amphotericin B (AMB) compared to triazoles. Specifically, A. fumigatus showed greater resistance to AMB, with only 23.28% of isolates being susceptible, while the majority of isolates were susceptible to triazoles like itraconazole (ITR) and posaconazole (POS). POS demonstrated the highest efficacy against all species. Sequencing revealed mutations in the promoter region of the cyp51A gene and at positions Y121F and E247K in A, fumigatus which confer resistance to ITR, voriconazole (VRC), and POS.

Conclusion

These findings contribute to a better understanding of the epidemiology and antifungal resistance pattern of Aspergillus species in the region, providing valuable insights for the management of Aspergillus-related infections.

Routine laboratory screening for cyp51a-related azole resistance in Aspergillus fumigatus using Etest: Concordance with gene sequencing

We evaluated the combined performance of itraconazole and voriconazole Etest® gradient concentration strips for the detection of Aspergillus fumigatus azole resistance associated with cyp51a mutations confirmed by gene sequencing. Among 118 A. fumigatus clinical isolates collected in a French center, 6 (5%) had azole resistance mutations, 5 of which were probably of environmental origin. Using recent method-dependent epidemiological cutoff values as thresholds, the combination's sensitivity and specificity were 100% [95% confidence interval 61-100] and 99% [95-100]. Our results support itraconazole and voriconazole Etest® combined use as a promising self-sufficient method for simple, efficient and reliable cyp51a-related azole-resistant A. fumigatus detection.

Exploring the role and mechanisms of the PMA gene in Aspergillus fumigatus

In the realm of aspergillosis, a critical concern for immunocompromised patients facing Aspergillus fumigatus, effective management hinges on understanding fungal growth, stress resistance, and response to antifungal treatments. Our study investigates the crucial role of fungal plasma membrane proton ATPase (PMA) in nutrient absorption, intertwined with growth and antifungal susceptibility. We employed a high-throughput knockout method to create the PMA gene knockout mutant, ΔAfu-PMA1, in A. fumigatus, alongside a complementation strain. Antifungal susceptibility to triazoles was assessed by micro-dilution method and E-test, revealing decreased sensitivity to voriconazole in ΔAfu-PMA1. Comparative analysis demonstrated significant growth differences, with wild-type strain surpassing ΔAfu-PMA1 by 3.2-fold. Under oxidative stress and heightened osmotic pressure, ΔAfu-PMA1 showed notable growth defects. Loss of PMA led to increased ergosterol and decreased ATP content, alongside pH changes in the culture medium. Transcriptome sequencing unveiled revealed a reduced expression of genes associated with ribosome function, the MAPK pathway, endoplasmic reticulum, and the transport and metabolism of fats, sugars, and proteins in ΔAfu-PMA1, highlighting PMA's regulatory role in growth and adaptation. These findings emphasise PMA as a potential target for future antifungal drugs, offering hope in combating aspergillosis.

Pharmacological management of invasive mold infections in solid organ transplant recipients

INTRODUCTION

Solid organ transplant (SOT) recipients face an increased susceptibility to invasive fungal infection (IFI) due to filamentous fungi. Post-transplant invasive aspergillosis (IA) and mucormycosis are related to exceedingly high mortality rates and graft loss risk, and its management involve a unique range of clinical challenges.

AREAS COVERED

First, the current treatment recommendations for IA and mucormycosis among SOT recipients are critically reviewed, including the supporting evidence. Next, we discussed particular concerns in this patient population, such as drug-drug interactions (DDIs) between triazoles and post-transplant immunosuppression or treatment-related toxicity. The role for immunomodulatory and host-targeted therapies is also considered, as well as the theoretical impact of the intrinsic antifungal activity of calcineurin inhibitors. Finally, a personal opinion is made on future directions in the pharmacological approach to post-transplant IFI.

EXPERT OPINION

Despite relevant advances in the treatment of mold IFIs in the SOT setting, such as the incorporation of isavuconazole (with lower incidence of DDIs and better tolerability than voriconazole), there remains a large room for improvement in areas such as the position of combination therapy or the optimal strategy for the reduction of baseline immunosuppression. Importantly, future studies should define the specific contribution of newer antifungal agents and classes.