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Biological characterization of Candida parapsilosis haploids induced by voriconazole.

OBJECTIVES: Candida parapsilosis is an important opportunistic fungal pathogen causing serious human infections in nosocomial settings. It has long been thought that C. parapsilosis has a diploid genome with a high homozygosity between chromosome homologs. METHODS: In this study, we report the discovery of C. parapsilosis haploids induced by voriconazole, a triazole with broad antifungal activity against fungal pathogens, in an experimental evolutionary assay. RESULTS: The haploid strains were able to undergo auto-diploidization under in vitro culture conditions or during systemic infection at a low frequency. Compared to the progenitor diploid strain, C. parapsilosis haploid and auto-diploid strains exhibited a reduced ability of invasive growth and biofilm formation. Global transcriptional expression analysis indicated that haploid and auto-diploid strains had a similar transcriptomic profile, which showed a remarkable difference from the progenitor diploid strain perhaps due to the loss of chromosome heterozygosity. Moreover, the haploid and diploid strains had distinct fungal burdens in different animal tissues, suggesting the haploid state could have a colonization advantage over the diploids in certain tissues such as the brain and spleen. CONCLUSIONS: The discovery of C. parapsilosis haploids not only sheds lights on the biology of this important fungal pathogen, but also provides a tool for genetic modifications for the field.

Voriconazole

Impact of Contact Lens Use on Clinical Profile and Outcomes of Fungal Keratitis: An 8-Year Retrospective Study.

PURPOSE: To compare clinical characteristics, microbiological profiles, treatment strategies, and outcomes between contact lens-associated (CL) and noncontact lens-associated (non-CL) fungal keratitis. DESIGN: Retrospective, comparative clinical cohort study. METHODS: A review of culture-proven fungal keratitis treated at a tertiary referral center between 2018 and 2025 was conducted. Cases were categorized as CL or non-CL-associated. Demographic, clinical, microbiological, treatment, and outcome data were analyzed and compared between groups. RESULTS: Thirty-seven eyes were included, comprising 16 CL and 21 non-CL cases. CL users presented earlier than non-CL patients (median 7 vs 14 days, P = .007) and had fewer associated ocular risk factors (31% vs 81%, P = .001). Baseline visual acuity and infiltrate size did not differ significantly between groups. Candida species were isolated in 21% cases, Fusarium in 16% and Aspergillus in 8%. Fusarium (19% vs 13%) and Candida (24% vs 19%) infections were slightly more frequent in non-CL cases. Overall, filamentous fungi were the predominant organism group. Topical voriconazole was the most frequently used antifungal agent (78%). All CL-associated cases resolved with medical therapy alone, with a median time to resolution of 38 days (IQR 22-58). In contrast, 76% of non-CL cases resolved medically (median 42 days, IQR 32-76), while 23% required therapeutic keratoplasty (P = .04). Final visual acuity was comparable between groups (logMAR 0.2 vs 0.5, P = .56). CONCLUSION: Contact lens-associated fungal keratitis is characterized by earlier presentation and fewer underlying ocular comorbidities, with favorable outcomes achieved through medical therapy alone. Despite similar microbiological profiles and treatment approaches, noncontact lens-associated fungal keratitis more frequently follows a complicated course requiring surgical intervention.

Humans

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 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

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

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

A new MRR1 gain-of-function mutation involved in cross-resistance to antifungal agents in the fungal priority pathogen Candida parapsilosis.

OBJECTIVES: Candida parapsilosis is a leading cause of invasive candidiasis globally, with rising reports of fluconazole resistance threatening its clinical management. Among the mechanisms involved, gain-of-function mutations in the MRR1 gene have emerged as key drivers of antifungal resistance. We aimed to investigate a novel amino acid substitution (G982E) in the Mrr1 zinc cluster transcription factor, identified in a fluconazole-resistant C. parapsilosis isolate from a patient exposed to fluconazole. METHODS: Using CRISPR-Cas9 genome editing, we introduced the G982E variant into two fluconazole-susceptible C. parapsilosis genetic backgrounds. The antifungal susceptibility of the engineered mutants was assessed in vitro against a broad panel of systemic antifungal agents. A Galleria mellonella infection model was also used to evaluate the impact of the G982E variant on antifungal treatment efficacy and virulence in vivo. RESULTS: Acquisition of the G982E substitution dramatically altered the antifungal susceptibility profile, particularly for fluconazole for which the MIC increased to >256 &#xb5;g/mL. However, the magnitude of the MIC increase varied by azole, with the greatest increase seen for fluconazole (>9-10-fold), followed by voriconazole (5-fold), isavuconazole (3-fold), but also flucytosine (1.5-fold). In contrast, susceptibility to posaconazole remained largely unchanged. In vivo, this new variant conferred fluconazole treatment failure but was associated with a significant reduction in virulence. CONCLUSIONS: The G982E is a novel Mrr1 gain-of-function mutation driving high-level fluconazole resistance in C. parapsilosis. These findings reinforce the central role of Mrr1 in antifungal resistance, underscore the functional diversity of its mutational landscape, with potential implications for fungal fitness and transcriptional regulation.

Candida parapsilosis

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