Mycopathologia最新文献

Background: Mucormycosis is a rare, destructive, and life-threatening angio-invasive fungal infection caused by fungi of the order Mucorales. This study highlights the urgent need for more extensive research in this regard. We aimed to assess the epidemiology of mucormycosis at eight tertiary-care centers in Iran over ten years (2010-2020).

Methods: In the current retrospective study, eligible patients were included based on positive histopathology and direct microscopy by potassium hydroxide (KOH). Data collection started on July 26, 2021, and included data from February 15, 2010, to May 16, 2020.

Results: Diabetes mellitus was the chief underlying condition related to mucormycosis. Rhino-cerebral, rhino-sino, and rhino-sino-orbital infections were observed in 53.2%, 23.8%, and 23% of these patients. Among the 108 cases with a culture, Rhizopus species were the most prevalent, followed by Mucor species. Over half of the patients received surgery/antifungal treatment, with an overall antifungal prescribing rate of 66.7% of patients within the study period. However, surgery was associated with better clinical outcomes than surgery/antifungal treatment. The antifungals prescribed were mainly amphotericin B, posaconazole, and amphotericin-posaconazole. Most patients with mucormycosis infection were admitted in the summer. Overall mortality in the identified cases was 30.6%, with the highest mortality rate in patients diagnosed with pulmonary infection.

Conclusion: The current study is the largest single-country retrospective study on the topic, with 601 mucormycosis cases. It may uncover gaps in knowledge, develop recommendations for future studies, and clarify the clinical and epidemiological aspects of mucormycosis. However, future studies and clarification of mucormycosis's clinical and epidemiological aspects are highly recommended.

Introduction: Aspergillus fumigatus poses significant clinical challenges due to its increasing azole resistance. This study investigates the sdh1 gene's role in regulating azole susceptibility, mitochondrial function, and virulence.

Materials and methods: Fungal strains were co-cultured with varying concentrations of succinate dehydrogenase inhibitors (SDHIs). Post-treatment azole minimum inhibitory concentrations (MICs) were determined using broth microdilution method, while succinate dehydrogenase subunit (SDH) expression changes were analyzed via RT-qPCR. Using A. fumigatus MFIG001 as the parental strain, sdh1 knockout mutant (Δsdh1) and complemented strain (Δsdh1::sdh1⁺) were constructed through homologous recombination. Detect the hyphal growth rate of Δsdh1, MICs and the changes in virulence within the Galleria mellonella infection model. Mitochondrial function was evaluated by measuring SDH activity, ATP content, and reactive oxygen species (ROS) levels. Transcriptomic changes were analyzed using RNA-seq and RT-qPCR, with efflux pump activity validated through Rhodamine 6G accumulation assays.

Results: Exposure to subinhibitory concentrations of SDHIs induced azole resistance in A. fumigatus, with 4.12% of strains exhibiting reduced susceptibility to voriconazole, itraconazole, and posaconazole. RT-qPCR analysis revealed significant downregulation of sdh1 in resistant strains, implicating its role in resistance development. Deletion of sdh1 resulted in an 8- to 16-fold increase in triazole MICs, confirming its role as a negative regulator of azole susceptibility. Phenotypically, the Δsdh1 strain exhibited impaired growth, reduced sporulation, and diminished efficacy of azole treatment in the G. mellonella infection model. Furthermore, Δsdh1 exhibited severe mitochondrial dysfunction, including reduced SDH activity, decreased ATP levels, elevated ROS, and impaired antioxidant defenses. RNA-seq analysis revealed that the deletion of sdh1 upregulated the expression of efflux pump genes (e.g., cdr1B, abcB, mdr4), while Rhodamine 6G efflux assays demonstrated significantly enhanced efflux activity.

Discussion: These results identify sdh1 as a critical determinant of azole susceptibility through dual mechanisms: mitochondrial function maintenance and efflux pump regulation. The observed SDHI-induced cross-resistance suggests agricultural fungicides may drive environmental selection of azole-resistant strains. While sdh1 deletion increased drug tolerance through efflux activation, the concurrent mitochondrial damage reduced pathogenic fitness, revealing compensatory evolutionary constraints. This work highlights the need to monitor non-target effects of agricultural SDHIs on clinical antifungal resistance.

Candida is a common and harmless component of the vaginal microbiota, present in approximately 50% of women of reproductive age. In specific conditions like pregnancy, Candida may cause chronic or recurrent infections which significantly impair quality of life. Additionally, due to the possibility of vertical transmission, it may lead to life-threatening infections in newborns. Timely screening, suspicion and identification of the causative agent are critical determinants of patient outcomes. Candida albicans (CA) remains the most prevalent species, but other non-albicans Candida (NAC) species and other non-Candida yeast (NCY) also play an important role in vulvovaginal infections. Due to the lack of precise local epidemiological data, this study aimed to determine the 10-year prevalence of CA, NAC and NCY species (spp.) in symptomatic pregnant women in Serbia using identification Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) for species identification. The total of 2,142 cases were examined (2013-2023) and the laboratory positivity was 48.3% (n = 1,035). The prevalence of CA, NAC and NCY were 74%, 23% and 3%, respectively. Biochemical and proteomic identification methods showed 100% concordance for CA, C. krusei (Pichia kudriavzevii), C. kefyr (Kluyveromyces marxianus), C. lusitaniae (Clavispora lusitaniae), and C. zeylanoides (Pichia norvengensis). Biochemical misidentification was observed for C. tropicalis (Lodderomyces sp.), C. glabrata (Nakaseomyces glabrata), and Saccharomyces cerevisiae. A global trend highlights the importance of renamed and reclassified yeast species in vaginal infections, supporting the reconsideration of the current disease name VVC in favor of the term vulvovaginal yeast infection (VYI). The prevalence of emerging NAC and NCY species is increasing but remains underestimated. There is a need for new laboratory diagnostic guidelines to enable timely and accurate identification, as this is crucial for guiding appropriate treatment and improving outcomes.

This report describes two cases of Curvularia geniculata keratitis, a rare form of fungal keratitis successfully managed with natamycin-based therapy. Both patients presented with characteristic feathery corneal infiltrates following ocular trauma. In vivo confocal microscopy and direct microscopy revealed septate filamentous fungi, and the isolates were definitively identified as C. geniculata through sequence analysis of the translation elongation factor 1-alpha (tef1-α) gene. Antifungal susceptibility testing showed sensitivity to natamycin at 2 μg/mL for both isolates, with variable sensitivity to other antifungal agents. Patient 1 was treated with a combination of topical natamycin and voriconazole, while Patient 2 received natamycin monotherapy. Both patients achieved complete healing and excellent visual outcomes. These cases underscore the importance of accurate molecular identification for species differentiation within the Curvularia genus and demonstrate the efficacy of natamycin-based therapy for C. geniculata keratitis. The choice between monotherapy and combination therapy may be guided by clinical severity and antifungal susceptibility testing. This report contributes to the understanding of the clinical features, diagnosis, and management of this rare condition and highlights the potential value of susceptibility testing in guiding treatment decisions.

Introduction: Fungal keratitis (FK), a severe ocular infection caused primarily by Fusarium spp. and Aspergillus spp., remains a major cause of blindness worldwide. Current treatment relies on antifungal agents, though emerging azole resistance in Aspergillus fumigatus complicates therapeutic outcomes.

Materials and methods: We isolated a clinical FK strain and assessed its antifungal susceptibility using broth microdilution and E-test methods, followed by sequencing of the cyp51A gene's promoter region and coding sequence (CDS) to identify resistance-associated mutations.

Results: The isolate, confirmed as A. fumigatus (Aftr46-001) via ITS and β-tubulin sequencing, exhibited elevated minimum inhibitory concentrations (MICs) 16 µg/mL for itraconazole (ITC), 32 µg/mL for isavuconazole (ISA), 32 µg/mL for voriconazole (VRC), and 1 µg/mL for posaconazole (POS) by broth microdilution. E-test results revealed an ITR MIC of 12 µg/mL, ISA MIC 32 µg/mL, VRC MIC 32 µg/mL, and POS MIC of 2 µg/mL. The isolate exhibited MICs values at or above the CLSI and EUCAST epidemiological cutoff values (ECVs): 1 µg/mL for ITC, ISA, and VRC according to CLSI (with insufficient data to establish a POS ECV), and 1 µg/mL for ITC and VRC, 2 µg/mL for ISA, and 0.25 µg/mL POS per EUCAST criteria. Genotypic analysis identified a 46-nucleotide tandem repeat in the cyp51A promoter and two nonsynonymous mutations (Y46F, F70L).

Discussion: This represents the first report of a cyp51A TR46/Y46F/F70L-harboring A. fumigatus strain isolated from FK, with potential agricultural environmental origins, suggesting that this mutation may have become a potential driver of azole-resistant FK in areas with high agricultural exposure, urgently needing to be included in local treatment guidelines and active surveillance systems. The isolate's resistance to all tested azoles underscores the clinical challenge posed by this genotype. Following this combined intervention, the patient's left eye vision improved from counting fingers at 1 m upon admission to a final visual acuity of 0.3, indicating that combined surgery and local high-dose drug delivery can serve as an effective strategy for drug-resistant FK. These findings highlight the importance of monitoring azole-resistant A. fumigatus strains to guide clinical treatment. The global increase in azole drug resistance further highlights the urgency and importance of rapid and accurate pathogen identification and drug resistance testing in the current environment.

Objectives: Candida albicans (C. albicans) is a common opportunistic fungal pathogen that poses a serious threat to human health. Autophagy inhibition decreased the resistance of C. albicans. This study investigated the antifungal activity of autophagy inhibitor chloroquine (CQ) against C. albicans biofilms and its synergistic potential with antifungal drug, and the underlying mechanisms.

Methods: The inhibitory effect of CQ on C. albicans biofilms was determined using the XTT assay. The interactions between CQ and antifungal drugs were evaluated using the FICI and ΔE models. The in vivo efficacy and biosafety were assessed in a murine model with oral candidiasis. The antifungal effects were further evaluated through time-kill assays, live/dead staining, and scanning electron microscopy. The autophagic regulation was analyzed using the expression of autophagy-related genes and proteins, reactive oxygen species (ROS), and alkaline phosphatase (ALP), and an ATG9 deletion strain was used to confirm the involvement.

Results: CQ exhibited antifungal activity against both standard and drug-resistant C. albicans strains, and showed significant synergy with amphotericin B (AmB). In vivo, CQ alone or in combination with AmB effectively against oral candidiasis in mice with good biosafety. Mechanistically, CQ alone or combined with AmB downregulated autophagy-related gene and protein expression, elevated ROS levels, and suppressed ALP activity. Consistently, ATG9 deletion reduced CQ efficacy in vitro and vivo, confirming CQ's antifungal effect via autophagy inhibition.

Conclusions: CQ enhances antifungal activity against C. albicans biofilms in vitro and in vivo by inducing oxidative stress and inhibiting autophagy, and exhibits synergistic effects with AmB.

Due to the recent unprecedented global rise of Candidozyma auris in hospital environments the members of the Candidozyma haemuli species complex have raised significant interest of clinicians and researchers. Until the finding of C. auris, the species complex did not receive much attention as the known pathogenic species were only rarely encountered in hospitals and clinical diagnostic laboratories. During the past years several new species were described, such as Candidozyma khanbhai and Candidozyma vulturna, that were found to be of clinical importance. Here, we used phylogenetic and phenotypic analyses -including antifungal susceptibility testing- to characterize and describe a new and potentially clinically relevant yeast that we obtained from clinical specimen and flowers, representing the proposed novel species Candidozyma molenica.

Aspergillosis is one of the most common human fungal infections. The invasive form of this infectious disease has high mortality rates. Moreover, antifungal resistance has been increasing, thereby limiting treatment options. In Iran, limited species distribution, genotyping and susceptibility data regarding aspergillosis is available, especially during the COVID-19 pandemic. In the current study, 124 patients with proven (n = 31), probable (n = 24) and possible (n = 46) aspergillosis and aspergillus colonization (n = 19) were investigated. Isolates were identified to species level based on calmodulin sequencing. Antifungal susceptibility testing was performed with microbroth dilution against common antifungal agents, i.e. amphotericin B, azoles and echinocandins. Additionally, short tandem repeat genotyping was conducted on common Aspergillus species to assess genetic relatedness. Aspergillus flavus was the most common species for proven aspergilossis cases, followed by identification of single cases of A. fumigatus, A. terreus, A. niger. These Aspergillus species were also mostly found in other patients with probably aspergillosis, in addition to four cases of possible aspergillosis with rare or cryptic species A. candidus, A. citrinoterreus, A. tubingensis and A. fumigatiaffinis, respectively. Using available epidemiological cutoff values (ECVs) no isolates were non-wild type to the tested antifungal drugs, while the A. fumigatiaffinis and A. citrinoterreus isolate demonstrated reduced susceptibility to respectively amphotericin B and Itraconazole, and amphotericin B only. With high-resolution short tandem repeat genotyping, several A. flavus clusters were found and their spatial and temporal clustering suggested nosocomial origins. To conclude, aspergillosis cases in Iran were caused by diverse but susceptible species, with A. flavus being dominant and associated with several events of potential nosocomial transmission.

The rising incidence of invasive fungal infections has been accompanied by an increasing prevalence of antifungal resistance among fungal pathogens. Rapid identification of causative agents and their antifungal susceptibility profiles is critical for initiating timely, species-specific targeted therapy. In this context, we evaluated a MALDI-TOF MS-based method for the rapid identification of clinically relevant yeast species directly from blood cultures and body fluids, coupled with direct antifungal susceptibility testing (Direct-AFST). Our study evaluated over 700 yeast isolates, encompassing diverse Candida and non-Candida species, using MALDI-TOF MS. Additionally, antifungal susceptibility was assessed for 250 isolates, demonstrating excellent categorical agreement between Direct-AFST and conventional culture-based AFST (Culture-AFST). Our findings highlight the clinical utility of MALDI-TOF MS for accurate and rapid yeast identification directly from positive blood cultures, irrespective of microbial load or sample preparation method. Furthermore, the successful application of Direct-AFST underscores its potential for early detection of antifungal resistance, significantly reducing diagnostic turnaround times and improving patient management.