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Evaluation of three Aspergillus antibody assays for screening of chronic pulmonary aspergillosis: prospective diagnostic accuracy study.

OBJECTIVES: Chronic pulmonary aspergillosis (CPA) is a frequent complication of pulmonary tuberculosis (PTB), particularly in high-burden settings where access to reliable serological diagnostics remains limited. We evaluated the diagnostic performance of two immunochromatographic technology (ICT) lateral flow assays (LFAs) and an ELISA for CPA screening among patients with active or previously treated PTB. METHODS: In this two-year prospective multicentre diagnostic evaluation, serum from adults with prior or active PTB was tested using the Era Biology Aspergillus IgG ICT LFA, LDBio Aspergillus IgG/IgM ICT LFA, and Bordier Aspergillus fumigatus IgG ELISA. CPA diagnosis was established using a consensus composite reference standard incorporating clinical, immunological, radiological, and microbiological criteria. The Bordier ELISA was used as part of the immunological component of the consensus CPA diagnosis, with a cutoff optical density of ≥1.0. Diagnostic accuracy, agreement statistics, receiver operating characteristic analysis, and latent class analysis (LCA) were performed. RESULTS: Among 340 participants, 24 (7.06%) had CPA. Proportion of participants with positive antibody tests among all tested individuals were 6.76% for LDBio ICT LFA, 20.0% for Era Biology ICT LFA, and 11.47% for Bordier ELISA. Against consensus CPA diagnosis, Bordier ELISA showed 87.50% sensitivity and 94.30% specificity, LDBio ICT LFA 58.33% sensitivity and 97.15% specificity, and Era Biology LFA 66.67% sensitivity and 83.54% specificity. LCA estimated CPA prevalence at 7.72%. LCA-derived sensitivities and specificities were 86.58% and 99.92% for LDBio ICT LFA, 83.39% and 85.31% for Era Biology LFA, and 79.10% and 94.19% for Bordier ELISA. CONCLUSIONS: The Bordier ELISA showed high sensitivity and specificity, while the LDBio ICT LFA demonstrated very high specificity with strong LCA-derived performance. These findings support the use of ELISA for laboratory diagnosis and ICT as a point-of-care screening tool for CPA in resource-limited settings. Era Biology Aspergillus IgG LFA demonstrated moderate sensitivity and acceptable diagnostic performance, indicating its potential utility as a supplementary screening assay for CPA in settings where rapid, point-of-care testing is required.

Humans

Triazole-resistant Aspergillus fumigatus in the Netherlands between 1994 and 2022: a genomic and phenotypic study.

BACKGROUND: Aspergillus fumigatus is the main cause of invasive aspergillosis and triazole antifungals are the primary treatment option. The effectiveness of triazole therapy is hampered by the emergence of resistance, mainly caused by mutations in the cyp51A gene and a tandem repeat (TR) of 34 bases (TR34/Leu98His) and 46 bases (TR46/Tyr121Phe/Thr289Ala) in the promoter region, which correspond with signature triazole resistance phenotypes. We aimed to investigate the occurrence of triazole phenotype and genotype variation over a 29-year period in the Netherlands. METHODS: In this genomic and phenotypic study, we screened all clinical A fumigatus isolates from Dutch hospitals collected between Jan 6, 1994, and Dec 31, 2022, for resistance to triazole using agar-based methods, and characterised them by sequencing the cyp51A gene and in vitro susceptibility testing using the European Committee on Antimicrobial Susceptibility Testing reference method. Whole-genome sequencing was performed on selected isolates, including those harboring TR34 variants, high-frequency single-nucleotide polymorphisms, and wild-type strains. Clinical information such as age, underlying disease, diagnosis, therapy, and outcomes was collected for patients who had isolates cultured at the Radboud University Medical Centre, Nijmegen, Netherlands, between Jan 1, 2017, and Dec 31, 2022. FINDINGS: 1979 (15&#xb7;6%) of the screened 12&#x2009;679 A fumigatus isolates harboured cyp51A triazole resistance mutations, predominately TR34/Leu98His sensu stricto in 1338 (67&#xb7;6%) resistant isolates and TR46/Tyr121Phe/Thr289Ala sensu stricto in 332 (16&#xb7;8%) resistant isolates. Phenotype and genotype variations were observed in 325 (17&#xb7;2%) triazole resistant isolates harbouring a TR-resistance mechanism, including 12 cyp51A genotype variants. Whole-genome sequencing showed that isolates with combinations of TR34-based and TR46-based polymorphisms seemed to be derived from separate populations, but there was some overlap. 59 cases of proven or probable invasive aspergillosis were identified, including 13 triazole-resistant cases, of which three were caused by genotype variants. Mixed genotype infection was observed in 11 (84&#xb7;6%) of 13 triazole-resistant patients and the number of antifungal treatment switches was higher compared with triazole-susceptible disease (p<0&#xb7;0001). INTERPRETATION: Our study showed variation in triazole genotypes and phenotypes in clinical A fumigatus isolates with cyp51A-mediated resistance, some of which were cultured from triazole-resistant invasive aspergillosis cases. Triazole resistance variation and mixed A fumigatus genotypes represent a major challenge in clinical management of Aspergillus diseases because current molecular diagnostic tools will increasingly fail to predict the resistance phenotype, underscoring the need for improved detection methods. FUNDING: National Key Research and Development Program of China, National Natural Science Foundation of China, and Wellcome Trust.

Aspergillus fumigatus

The black aspergilli (Aspergillus niger complex) and their role in human, animal, and plant diseases.

SUMMARYThe Aspergillus niger complex, also known as the black aspergilli or section Nigri, comprises a diverse group of filamentous fungi with wide-ranging ecological, industrial, and pathogenic significance. While traditionally associated with food spoilage and industrial fermentation, black aspergilli have emerged as opportunistic pathogens affecting humans, animals, and plants. This review provides a comprehensive synthesis of the taxonomy, ecology, pathogenicity, and antifungal resistance of the A. niger complex. Advances in phylogenetics and whole-genome sequencing have clarified the taxonomy of section Nigri, now comprising six core species in series Nigri. Clinically, A. niger complex is implicated in various conditions, including otomycosis, keratitis, cutaneous infections, onychomycosis, chronic pulmonary aspergillosis, and, less commonly, invasive aspergillosis. In animals, black aspergilli have been isolated from respiratory, cutaneous, and systemic infections, particularly in immunocompromised or stressed hosts. Plant pathogenicity is significant, with A. niger complex contributing to pre- and post-harvest spoilage and producing mycotoxins such as ochratoxin A and oxalic acid. The common finding of elevated minimum inhibitory concentrations (MICs) to triazoles, particularly in both environmental and clinical isolates, raises concern, with underlying mechanisms differing from those characterized in A. fumigatus. Reduced susceptibility is potentially driven by efflux pumps and environmental exposure to azole fungicides. Due to commonly higher MICs, antifungal therapy with itraconazole and isavuconazole may have reduced efficacy, and alternatives such as voriconazole or posaconazole should be considered, guided by susceptibility testing where available. This review emphasizes the need for a One Health approach to managing black aspergilli, integrating surveillance, diagnostics, and targeted interventions across human, veterinary, and agricultural sectors.

Humans

Triazole resistance in clinical Aspergillus fumigatus isolates in India, a multicenter surveillance study.

BACKGROUND: Triazole resistance in Aspergillus fumigatus is a global public health concern associated with treatment failure, notably in invasive aspergillosis. However, population-level data on triazole resistance from India remain limited, with most reports originating from single-center studies. METHODS: We conducted a multicenter surveillance study to assess the prevalence of triazole resistance among clinical A. fumigatus isolates across India. Antifungal susceptibility testing was performed using the CLSI broth microdilution method (M38-Ed3), and molecular characterization was conducted on resistant isolates. A total of 518 isolates were analyzed: 115 prospectively collected from 13 tertiary-care hospitals from 2015-2020, and 403 archived isolates obtained from the National Culture Collection of Pathogenic Fungi (1994-2020). RESULTS: The overall pooled prevalence of non-wildtype isolates was 4.1% for itraconazole (95% CI: 2.54-6.17%), 3.9% for posaconazole (95% CI: 2.39-5.94%), while 1.4% were resistant to voriconazole (95% CI: 0.55-2.77%). One multi-azole-resistant isolate from an immunocompromised, mold-active triazole-na&#xef;ve patient carried the TR34/L98H mutation, suggesting environmental acquisition. Prevalence of resistance did not differ significantly across geographic regions or between public and private sector hospitals. Linear regression analysis revealed a significant temporal increase in median MICs of all three licensed triazoles between 1994 and 2020. Approximately 29% of isolates exhibited amphotericin B MICs exceeding the epidemiological cutoff value; however, the clinical significance of this finding remains uncertain. CONCLUSIONS: Azole resistance among clinical A. fumigatus isolates in India remains uncommon (<5%), supporting the continued use of triazoles as first-line therapy. However, the observed temporal increase in triazole MICs underscores the need for sustained national surveillance to detect emerging resistance trends.

Aspergillus fumigatus

An Aspergillus luchuensis isolated from a patient with hemoptysis insights from a comprehensive genome-based analysis: Case report.

RATIONALE: Asp luchuensis, a member of the A niger group, is widely used in food fermentation and rarely causes invasive pulmonary aspergillosis (IPA) in humans. Clinical cases of IPA induced by this strain are extremely scarce, and its genomic characteristics, virulence profiles, and pathogenic mechanisms remain poorly understood, resulting in insufficient clinical recognition of its invasive infection potential. PATIENT CONCERNS: A 57-year-old immunocompetent non-neutropenic male patient with a long-term smoking and drinking history presented with unexplained severe cough and massive hemoptysis (approximately100&#x2009;mL) without other typical infectious symptoms. DIAGNOSES: Combined with chest computed tomography (CT) inflammatory lesions, positive galactomannan test, fungal PCR and metagenomic next-generation sequencing results, the patient was definitively diagnosed with probable A luchuensis-induced IPA. Genomic and transcriptomic analyses confirmed the pathogen as a variant A luchuensis strain with 3 key hypervirulence genes, highly active mitochondrial energy metabolism, and no specific antifungal resistance genes. INTERVENTIONS: The patient received standardized intravenous antifungal combination therapy with voriconazole and amphotericin B after confirmed diagnosis. OUTCOMES: The patient's cough and hemoptysis were significantly relieved after 10 days of treatment, with stable vital signs and no adverse drug reactions or disease progression. LESSONS: A luchuensis possesses strong invasive pathogenicity and can trigger IPA even in non-neutropenic immunocompetent individuals. Negative conventional microbial tests cannot exclude its infection, and mNGS is a reliable diagnostic tool. This strain is susceptible to routine antifungal drugs, and clinicians should raise awareness of atypical Asp species-induced invasive pulmonary infections.

Humans

Functional characterization of SHC-like triterpene cyclase genes in azole response and virulence-related traits of Aspergillus fumigatus.

Aspergillus fumigatus is a major opportunistic fungal pathogen, and increasing azole resistance poses a challenge for aspergillosis treatment. Squalene is an upstream precursor of ergosterol biosynthesis and may also be utilized by SHC-like triterpene cyclases, suggesting a potential link between squalene-associated metabolism, membrane adaptation, and azole response. However, the roles of SHC-like triterpene cyclase genes in A. fumigatus remain unclear. Here, we characterized three candidates, shc1, shc2, and shc3, using comparative bioinformatic analysis, gene deletion, phenotypic assays, azole susceptibility testing, transcriptomics, and host-interaction models. Sequence, genomic-context, phylogenetic, and structural analyses suggested divergence among the three candidates. Individual shc deletion caused limited effects on vegetative growth, whereas loss of shc1 mildly reduced susceptibility to voriconazole and posaconazole, as reflected by twofold MIC increases and lower inhibition rates. Transcriptomic analysis revealed distinct remodeling patterns, with &#x394;shc3 showing the broadest transcriptional changes despite no detectable MIC shift. Targeted metabolite profiling and PI uptake analysis further supported an association between shc deletion, sterol/hopane-type triterpenoid balance, and membrane-associated properties. shc deletion also altered epithelial cell interaction phenotypes, while &#x394;shc1 showed reduced lethality in Galleria mellonella. In clinical isolates, elevated shc transcription was associated with azole-resistant backgrounds. These findings suggest functional diversification among SHC-like triterpene cyclase genes and indicate that shc1 may contribute to azole-associated adaptation and virulence-related traits in A. fumigatus.

Aspergillus fumigatus

Pseudomonas aeruginosa adaptation and persistence in the aspergilloma microbiome revealed by integrated multi-omics.

Chronic pulmonary aspergillosis involves the formation of a fungal ball (aspergilloma) in lung cavities. Pseudomonas aeruginosa commonly co-colonizes these lesions; however, the in vivo mechanisms underlying its persistence are unknown. Using a multi-omics approach on resected aspergillomas, we defined the genomic, transcriptional, and metabolic adaptations of P. aeruginosa within this polymicrobial niche. We reconstructed high-quality P. aeruginosa genomes and identified a conserved core genome, along with accessory genes for secondary metabolism, virulence, and antimicrobial resistance. Phylogenomics revealed heterogeneous evolutionary paths among co-colonizing strains. Metatranscriptomics showed stark physiological heterogeneity, from metabolically aggressive to stress-adapted states. High expression of phenazine, quorum-sensing (PQS), siderophore, and secretion-system operons was corroborated by metabolomic detection of phenazine-1-carboxylic acid and 2-heptylquinolin-4(1H)-one, confirming active bacterial antagonism in vivo. Concurrent Aspergillus fumigatus transcriptomics revealed the activation of oxidative stress responses, secondary metabolism (eg fumagillin), and iron scavenging, demonstrating reciprocal competition. Host transcriptomics revealed patient-specific immune signatures that correlated with the metabolic activity of the co-colonizers. This work provides an integrated systems-level analysis of the tri-kingdom aspergilloma ecosystem. P. aeruginosa persistence is driven by genomic plasticity and context-dependent expression of competitive pathways, shaped within a chronic inflammatory environment. These findings redefine aspergillomas as active polymicrobial consortia, establishing a framework for targeting resilient microbial communities in chronic lung disease.

Multiomics

Gfa1 (glutamine fructose-6-phosphate aminotransferase) is essential for Aspergillus fumigatus&#xa0;growth and virulence.

BACKGROUND: Aspergillus fumigatus, the primary etiological agent of invasive aspergillosis, causes over 1.8 million deaths annually. Targeting cell wall biosynthetic pathways offers a promising antifungal strategy. Gfa1, a rate-limiting enzyme in UDP-GlcNAc synthesis, plays a pivotal role in the hexosamine biosynthetic pathway (HBP). RESULTS: Deletion of gfa1 (&#x394;gfa1) results in auxotrophy for glucosamine (GlcN) or N-acetylglucosamine (GlcNAc). Under full recovery (FR) conditions, where minimal medium is supplemented with 5&#xa0;mM GlcN as the sole carbon source, the &#x394;gfa1 mutant shows growth comparable to the wild-type (WT). However, when supplemented with 5&#xa0;mM GlcN and 55&#xa0;mM glucose, growth is partially repressed, likely due to carbon catabolite repression, a condition termed partial repression (PR). Under PR conditions, &#x394;gfa1 exhibits compromised growth, reduced conidiation, defective germination, impaired cell wall integrity, and increased sensitivity to endoplasmic reticulum (ER) stress and high temperatures. Additionally, &#x394;gfa1 demonstrates disruptions in protein homeostasis and iron metabolism. Transcriptomic analysis of the mutant under PR conditions reveals significant alterations in carbohydrate and amino acid metabolism, unfolded protein response (UPR) processes, and iron assimilation. Importantly, Gfa1 is essential for A. fumigatus virulence, as demonstrated in Caenorhabditis elegans and Galleria mellonella infection models. CONCLUSIONS: These findings underscore the critical role of Gfa1 in fungal pathogenicity and suggest its potential as a therapeutic target for combating A. fumigatus infections.

Aspergillus fumigatus

Rapid and reliable diagnosis of mucormycosis using colorimetric loop-mediated isothermal amplification.

Current diagnostic approaches for mucormycosis are often limited by low sensitivity and prolonged turnaround times, which result in delayed treatment and poor clinical outcomes. We developed a novel diagnostic method utilizing a colorimetric loop-mediated isothermal amplification (LAMP) assay for the rapid and sensitive detection of mucormycosis. The assay incorporates specifically designed primers capable of detecting as low as 0.001 picograms (pg) of spiked genomic DNA from Mucorales fungi. This LAMP assay demonstrated a high sensitivity of 98% and a 100% specificity of detecting fungal ribosomal DNA (rDNA) in bronchoalveolar lavage (BAL) samples collected from mice infected with Mucorales fungi (n = 48) or from an uninfected control group (n = 15). To align the assay with clinical antifungal therapy, a subset of infected mice was treated with either liposomal amphotericin B (LAMB) or a combination of LAMB and a humanized monoclonal antibody (VX-01) targeting the Mucorales-specific surface protein CotH3. Consistent with the treatment efficacy, the LAMP assay detected significantly lower fungal burdens in BAL samples from mice receiving the combination therapy compared to those treated with LAMB alone or placebo. Further validation was conducted using BAL samples from patients diagnosed with mucormycosis (n = 24) or aspergillosis (n = 17). The assay demonstrated a sensitivity of 79% and a specificity of 94%. These findings highlight the diagnostic potential of this LAMP-based assay as a point-of-care. Its high sensitivity, specificity, and rapid turnaround time position this assay as a promising tool for early and accurate detection of mucormycosis, with the potential to improve patient management and clinical outcomes.IMPORTANCEMucormycosis is a rapidly progressive and fatal fungal infection. Timely diagnosis is critical for effective treatment, yet current diagnostic tools are slow, insensitive, or require complex laboratory procedures. In this study, we developed and validated a colorimetric loop-mediated isothermal amplification (LAMP) assay that enables rapid and reliable detection of Mucorales DNA directly from bronchoalveolar lavage (BAL) specimens. The assay demonstrated high sensitivity and specificity in both experimental mouse models and clinical samples, producing results within 1 h without the need for sophisticated equipment. This simple, robust, and cost-effective molecular diagnostic tool holds great potential for early detection of mucormycosis, facilitating prompt antifungal therapy and improving patient survival.

Mucormycosis

Genetic diversity and antifungal susceptibility among ecological niche populations of Aspergillus flavus in Yaound&#xe9;, Cameroon.

Aspergillus flavus is a ubiquitous fungus commonly found in a variety of ecological niches including soil, crops, the air, and humans. In humans, it is the second leading cause of invasive aspergillosis (IA) and is linked to other illnesses through contamination of agricultural products with aflatoxins. As such, A. flavus threatens food safety, economic wellbeing, and human health, particularly in less developed regions and countries such as Cameroon. To mitigate these effects, farmers and clinicians rely on triazoles to reduce aflatoxin contamination and treat IA. However, a consequence of increasing triazole use is the emergence and spread of triazole resistance in both agriculture and clinics. To identify the prevalence of triazole resistance and the potential genetic relationships among triazole resistant and susceptible strains, this study investigated antifungal susceptibility to both clinical and agricultural triazoles and analyzed genetic variation among various ecological niche populations of A. flavus in Cameroon. Strain genotypes were obtained through analysis of six polymorphic microsatellite markers. Our analyses revealed that 30.3% (17/56) of the strains were resistant to at least one of the four triazoles, with increased minimum inhibitory concentrations found among crop-isolated strains. A Permutational Multivariate Analysis of Variance suggested limited ecological niche-based clustering of genotypes, consistent with frequent gene flow and dispersal among ecological niches. A multilocus linkage disequilibrium analysis revealed evidence of non-random recombination in A. flavus. Overall, this study elucidates the interplay between ecological pressures, antifungal resistance, and genetic differentiation, and invites alternative methods to control aflatoxin contamination in foods without the use of agricultural fungicides.

Aspergillus flavus

Clinical and Genomic Insights into the Allodiploid Hybrid Pathogen Aspergillus latus: A Retrospective Case Series.

Aspergillus latus is an emerging cryptic allodiploid hybrid pathogen within Aspergillus section Nidulantes that closely resembles related species and therefore prone to misidentification by routine diagnostic methods. Therefore, its true clinical burden is likely underestimated. In this study, we retrospectively characterized five patients with A. latus infections identified by metagenomic next-generation sequencing (mNGS) at a tertiary hospital in China. Clinical manifestations varied according to host immune status, ranging from a subclinical pulmonary lesion in an immunocompetent individual to aggressive disease in highly immunocompromised patients. Conventional microbiological methods showed limited sensitivity and consistently misidentified the isolates as A. nidulans, whereas mNGS enabled accurate detection of A. latus together with complex co-infections. Three viable clinical isolates were recovered for morphological characterization, antifungal susceptibility testing, and whole-genome sequencing (WGS). All tested isolates demonstrated reduced susceptibility to echinocandins but remained susceptible to mold-active triazoles and amphotericin B. Furthermore, WGS and macrosynteny analyses confirmed their allodiploid hybrid nature, revealing a mosaic genome derived from A. spinulosporus and an A. quadrilineatus-related lineage. Collectively, these findings highlight that A. latus may be missed by routine diagnostic methods and may exhibit a distinct antifungal susceptibility profile. Molecular approaches such as mNGS and WGS may therefore help achieve accurate species-level identification and support targeted antifungal therapy. Given this small retrospective case series, larger prospective and multicenter studies are needed to validate these observations and better define the epidemiology, clinical spectrum, and therapeutic implications of this emerging allodiploid hybrid pathogen.

Retrospective Studies

Diagnostic performance of panfungal PCR on tissue specimens for the diagnosis of invasive fungal diseases: a systematic review and meta-analysis of the Fungal PCR Initiative (FPCRI).

UNLABELLED: Invasive fungal diseases are difficult to diagnose because of the limited sensitivity of culture. Panfungal PCR amplicon sequencing assays (targeting ribosomal RNA, such as 18S, 28S, ITS) are recommended for fungal identification in histopathology samples showing fungal elements. However, data describing its overall performance and consistency are lacking. This systematic literature review and meta-analysis assessed the performance of panfungal PCR on formalin-fixed paraffin-embedded (FFPE) and non-fixed (fresh or frozen) tissue samples. A systematic literature search was performed to include studies reporting the use of panfungal PCR for fungal identification in FFPE or non-fixed tissue samples. PCR sensitivity and specificity were assessed using the reference standard of histopathology showing fungal elements. Quality assessment was performed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. Pooled estimates were obtained using random-effects meta-analysis. Twenty-eight studies were included. In FFPE samples (18 studies, 852 samples), sensitivity and specificity were 75.4% (95% confidence interval [CI], 59.2-86.6) and 93.5% (70.2-98.9), respectively. Sensitivity in non-fixed samples (13 studies, 207 samples) was 86.5% (74.7-93.3), while specificity could not be assessed (insufficient data). Comparative analyses showed a significantly higher sensitivity of panfungal PCR over culture (88.2%; 76-94.7 vs 52.2%; 39-65, P = 0.001). Sub-analyses could not demonstrate the superiority of one PCR target over another due to limited data. Panfungal PCR exhibited adequate sensitivity and good specificity in FFPE samples. Sensitivity was even higher in non-fixed samples and largely superior to culture. Nevertheless, large interstudy variability was observed, warranting interlaboratory studies to define the optimal PCR target and standardized protocols. IMPORTANCE: Invasive fungal diseases are difficult to diagnose because of the low sensitivity of culture. Panfungal PCRs are widely used for fungal identification in tissue specimens but suffer from heterogeneous procedures and performance. This meta-analysis shows an acceptable sensitivity (75.4% and 86.5% in fixed and non-fixed samples, respectively) and good specificity (93.5%) of panfungal PCR, supporting its use, not only on histopathology-positive fixed samples but also in non-fixed samples concomitantly with other diagnostic tools (cultures and fungal-specific PCRs if available). These results provide a strong basis for further standardization of panfungal PCR techniques via interlaboratory assays to assess reproducibility and optimize analytical protocols. CLINICAL TRIALS: This study is registered with PROSPERO as CRD42023461148.

Humans

Identification and characterization of non-canonical azole antifungal resistance pathways in Aspergillus fumigatus.

UNLABELLED: Human fungal infections, especially those caused by Aspergillus fumigatus, pose a significant global health threat, particularly in immunocompromised individuals. Azole antifungals are the primary treatment for this pathogen; however, the prevalence of azole-resistant A. fumigatus strains is steadily increasing. Mutations in cyp51A, which encodes an enzyme involved in ergosterol biosynthesis and the molecular target of the azoles, are well established to confer resistance in this fungal species. However, additional mechanisms governing resistance to this antifungal class remain understudied and poorly characterized, despite growing recognition of their importance in clinical resistance. In this study, we investigated the genetic basis of azole resistance in A. fumigatus isolates from clinical settings worldwide, with a particular focus on mechanisms independent of cyp51A (non-canonical). Using a combination of genomic and functional approaches, including whole-genome sequencing and transcriptomic analysis, we identified novel genetic variants and characterized population structure, advancing our understanding of the genetic diversity and evolutionary dynamics of resistance in A. fumigatus. By expanding our understanding of the complex genetic and molecular factors underlying azole resistance in this important human fungal pathogen, this research is poised to inform the development of novel antifungal strategies and contribute to global efforts to combat fungal infections. IMPORTANCE: Azole antifungals are the frontline therapy for infections caused by the opportunistic mold Aspergillus fumigatus, yet resistance to these drugs is rapidly increasing worldwide. Most studies have focused on mutations in cyp51A, the canonical target of azoles; however, a growing proportion of resistant clinical isolates lack these mutations, indicating that alternative resistance mechanisms are emerging. Here, we integrate population genomics, transcriptomics, and functional analyses across a global collection of isolates to define the architecture of cyp51-independent (non-canonical) azole resistance. We show that this resistance phenotype is strongly associated with a distinct population lineage and is driven by a highly polygenic network of metabolic, mitochondrial, and regulatory adaptations rather than single target site mutations. These isolates exhibit extensive transcriptional rewiring and metabolic remodeling under azole stress, suggesting distinct survival strategies beyond canonical resistance. Our findings reveal that azole resistance in A. fumigatus can evolve through diverse evolutionary routes and emphasize the need to monitor and therapeutically target non-canonical pathways that may increasingly contribute to antifungal treatment failure.

Aspergillus fumigatus