Current Medical Mycology最新文献

Background and purpose: Dermatophytosis, or ringworm, is a highly contagious fungal infection caused by dermatophytes, like Microsporum canis, which primarily affects cats and dogs and poses a significant zoonotic threat. Increasing prevalence of drug-resistant strains complicates the treatment of M. canis infections, necessitating the exploration of new therapeutic approaches. Nanotechnology, particularly copper oxide nanoparticles (CuO NPs), has emerged as a promising solution due to its potent antimicrobial properties and potential to overcome resistance. This study aimed to evaluate the antifungal efficacy of CuO NPs against M. canis isolates collected from companion animals. The goal was to develop more effective treatment options for dermatophytosis, addressing the need for alternative therapies and the challenge of antifungal resistance.

Materials and methods: CuO NPs were synthesized using a green chemistry approach, employing Eichhornia crassipes leaf extract. Concurrently, M. canis isolates were obtained from infected animals and cultured for purity. Antifungal activity of the CuO NPs against the isolates was assessed through disk diffusion and microdilution tests, and the results were statistically analyzed to confirm their significance. Cell dens (10 ⁵ .

Results:  The synthesized CuO NPs exhibited high purity, small size, and cubic morphology. Statistical analysis of the disk diffusion and microdilution tests confirmed the significant antifungal efficacy of CuO NPs against M. canis isolates (ANOVA, p<0.05). Minimum inhibitory concentration (MIC) values ranged from 500 to 1,000 ppm, while minimum fungicidal concentration (MFC) values were between 1,000 and 2,000 ppm. Average MFC/MIC ratio of 2.6, confirmed through paired t-test (p=0.003), demonstrated the fungicidal properties of the CuO NPs.

Conclusion: This study highlighted the potent antifungal capabilities of CuO NPs against M. canis, marking them as a promising alternative to conventional treatments. With further optimization and research, CuO NPs could revolutionize the management of dermatophytosis, offering a new frontier in combating drug-resistant fungal infections.

Background and purpose: Scedosporium apiospermum, a soil-dwelling fungus, is typically associated with localized infections, such as skin infections and osteomyelitis. However, it can also cause invasive central nervous system infections, including brain abscesses, particularly in immunocompromised individuals. Such infections are rare in immunocompetent individuals and often occur following trauma or environmental exposure. This report aimed to present a case of a fatal S. apiospermum brain abscess in an immunocompetent adult male, highlighting diagnostic and management challenges.

Case presentation: A 48-year-old immunocompetent male presented with a three-day history of persistent holo-cranial headache and left-sided weakness. Twenty days earlier, the patient had fallen into a sewer, likely exposing him to fungal pathogens. Initial imaging revealed a large right frontal intracranial lesion. Surgical resection of the abscess was performed, and antifungal therapy with voriconazole was initiated. Intraoperative findings revealed a thick, non-vascular abscess capsule containing yellow pus. Postoperative KOH mount confirmed fungal elements (hyaline septate hyphae). Despite aggressive management in the intensive care unit, including antifungal therapy, antibiotics, and supportive care, the patient developed septic shock and succumbed to cardiac arrest within 48 h of surgery.

Conclusion: This case underscores the rapid progression and severity of S. apiospermum infections in immunocompetent individuals, even with early surgical and medical intervention. It emphasizes the need for heightened clinical suspicion in cases involving trauma with potential environmental exposure. Prompt diagnosis, effective antifungal therapy, and multidisciplinary management are essential to improve outcomes in such cases.

Background and purpose: Essential oils (EO) have gained significant attention due to their natural antimicrobial and antifungal properties. However, their application is often limited due to poor solubility, volatility, and stability. Nanoemulsions, as advanced delivery systems, can overcome these limitations by enhancing the bioavailability and efficacy of EOs. Lemon EO, known for its broad-spectrum antimicrobial activity, is a promising candidate for nanoemulsion formulation. This study aimed to synthesize and characterize lemon EO nanoemulsions and evaluate their enhanced antimicrobial and antifungal potential, compared to crude oil.

Materials and methods: Lemon EO was first analyzed using gas chromatography-mass spectrometry (GC-MS) to identify its chemical composition. Lemon EO nanoemulsions were prepared using the spontaneous emulsification technique. The physicochemical properties, including particle size, polydispersity index (PDI), zeta potential, and stability, were characterized using dynamic light scattering. The antimicrobial and antifungal activities were assessed against Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis, Candida albicans, and Aspergillus fumigatus through minimum inhibitory concentration (MIC) and minimum bactericidal/fungicidal concentration (MBC/MFC) assays.

Results: The GC-MS analysis revealed the major chemical components of lemon EO, including limonene, β-pinene, and γ-terpinene. The nanoemulsions exhibited a mean particle size of about 15 nm, a low PDI (< 0.3), and a negative zeta potential, indicating high stability and homogeneity. The antimicrobial and antifungal activities of the nanoemulsions were significantly enhanced compared to the crude lemon EO, as demonstrated by lower MIC and MFC values. The nanoemulsions also showed excellent stability under various storage conditions.

Conclusion: This study demonstrated that lemon EO nanoemulsions are a stable delivery system with superior antimicrobial and antifungal properties. The GC-MS analysis provided valuable insights into the chemical composition of the EO, further supporting its efficacy. These findings suggest the potential of lemon EO nanoemulsions as a natural alternative for applications in food preservation, pharmaceuticals, and cosmetics.

Background and purpose: Today, with the development of critical patient care and the increase in intravascular invasive methods, the survival rate of patients diagnosed with hematological and solid organ malignancies is increasing, and unfortunately, the incidence of Candida parapsilosis candidemia is also increasing due to multiple risk factors. In this study, we aimed to determine the clinical-demographic characteristics of C. parapsilosis candidemia and the antifungal susceptibility profile of C. parapsilosis in pediatric patients with hematological and solid organ malignancies.

Materials and methods: The present study included pediatric patients with hematologic and solid organ malignancies presenting with signs and symptoms consistent with candidemia, in whom C. parapsilosis was isolated from blood and catheter cultures between January 2010 and August 2023.

Results: Thirty (65.2%) of the patients had hematologic and 16 (34.8%) had solid organ malignancies. In all patients, 23 (50%) had non-catheter-related candidemia and 23 (50%) had catheter-related candidemia. At least one of the risk factors examined was detected in these patients. Catheter-related candidemia was found to be more common in patients diagnosed with hematologic malignancy. The difference was found to be statistically significant (p= 0.030). Drug resistance rates of C. parapsilosis were 6.5% for amphotericin B, 6.5% for fluconazole, 2.2% for voriconazole and 2.2% for micafungin. No patient with caspofungin resistance was detected. The mean treatment duration of the patients was 21 days (min 3-max 103) and it was observed that amphotericin B and caspofungin were used most frequently in the treatment regimen. The mortality rate of patients with candidemia was 6.5%.

Conclusion: Our study showed that patients with hematologic malignancies exhibited a higher susceptibility to catheter-related C. parapsilosis candidemia compared to patients with solid organ tumors. Caspofungin resistance was not detected in our study, and we believe that each center should know its own antifungal drug sensitivity, determine the treatment regimen accordingly, and that catheters should be removed rapidly in patients with catheter-related C. parapsilosis candidemia in malignant patients.

Background and purpose: Candida albicans is currently recognised as an opportunistic pathogen that can cause many invasive infections. Resistance mechanisms and fungal virulence factors play an important role in the effectiveness of treatment. The aim of this study was to investigate the relationship between fluconazole resistance, proteinase activity and ERG11 (sterol 14-demethylase)- SAP2 (secreted aspartic protease 2) gene expression levels in C.albicans strains.

Materials and methods: Candida albicans strains isolated from patient samples sent to Medical Microbiology laboratory of Düzce University from various clinics were included in the study. Fluconazole susceptibilities of the isolates were determined by broth microdilution method. The increase in fluconazole MIC values at 48 hours and proteinase activities of the isolates were analysed. ERG11 and SAP2 gene expression levels were measured by real time qPCR.

Results: Fluconazole resistance rate was found to be 3.14% in 127 C. albicans strains. A moderate positive correlation was found between ERG11 and SAP2 values (p=0.029, r:0.655, p<0.001). There was no correlation between SAP2/ERG11 expression levels and fluconazole resistance. Proteinase positivity was detected in 81.1%, of 127 strains and no statistically significant correlation was found between proteinase activities and SAP2/ERG11 expression levels. While there was a statistically significant relationship between ERG11 expression levels and 48th hour MIC elevation, there was no statistically significant relationship between SAP2 levels and 48th hour MIC elevation.

Conclusion: In addition to the moderate positive correlation between ERG11 and SAP2 values, a significant correlation was found between ERG11 expression and fluconazole tolerance.

Background and purpose: Candidiasis is a prevalent fungal infection caused by various species of Candida, especially, C. albicans. The emergence of resistance to azole medications, which are frequently prescribed for the treatment of Candida infections, presents a significant challenge in the management of these infections.

Materials and methods: The present mini-review summarizes findings from a comprehensive search of articles published between 1999 and 2024, retrieved from Scopus, PubMed, and Web of Science. Studies were selected using specific keywords based on relevance to UPC2 gene functions, azole resistance mechanisms, and C. albicans biology.

Results: The UPC2 gene has become crucial in regulating drug resistance in C. albicans. This gene encodes a zinc (II)-Cys (6) transcription factor involved in the biosynthesis of sterols and contributes to resistance against azole antifungal drugs. When exposed to azoles, UPC2 in C. albicans enhances the expression of ergosterol biosynthesis genes, such as ERG2 and ERG11. Increased expression of ERG11 leads to reduced susceptibility to azoles by boosting the production of 14α-lanosterol demethylase, the primary target of these antifungal agents. Furthermore, UPC2 regulates sterol uptake under anaerobic conditions and manages other adaptations to environmental changes, all of which contribute to azole resistance.

Conclusion: Gaining insight into how the UPC2 gene contributes to azole resistance is essential for the development of effective strategies in the antifungal drug development process.

Background and purpose: Oral candidiasis (OC) is a common condition in HIV-infected individuals. This study aimed to identify the prevalence, associated factors, and causative agents of OC among HIV-infected patients in a general hospital in Vietnam.

Materials and methods: The study involved 393 HIV-infected individuals treated at The Tropical Diseases Center, Nghe An General Friendship Hospital, Vinh, Nghe An, Vietnam from January 2022 to May 2024. The sample collected from the buccal mucosa was seeded onto CHROMagar^TM Candida to isolate and identify the causative yeasts. Molecular identification was performed with restriction fragment length polymorphism assay using MspI restriction enzyme and sequencing of the internal transcribed spacer (ITS) region.

Results: The prevalence of OC was 10.7% (95% confidence interval 7.6 - 13.8). Patients with late WHO HIV clinical stage, poorer hygienic condition, or use of prosthetic were at a higher risk of OC. Ten yeast species were isolated, and 10 (23.8%) patients carried more than one type of yeast species. Out of 54 obtained isolates, Candida albicans comprised the most (62.9% isolates and 80.9% patients), followed by C. tropicalis (16.4% and 21.4% respectively). Overall, 27 patients (64.3%) were infected with C. albicans, and 15 patients (35.7%) were infected with non- albicans Candida, alone or in combination with C. albicans.

Conclusion: The prevalence of OC in HIV-infected patients was low and associated with both systemic and local factors. C. albicans was still the most common species but non- albicans Candida or coexistence of Candida species is frequent.

Background and purpose: Various species of microorganisms interact in a variety of ecological niches and can lead to infection. A biofilm of one or more species may form during the infectious process. Otomycosis can be brought on by etiologic agents, such as Staphylococcus aureus and Aspergillus niger. This study aimed to survey the antagonistic relationship between the gene expression biofilms of A. niger and S. aureus in the context of otomycosis-related biofilm formation.

Materials and methods: This study examined single-species biofilms of A. niger and S. aureus, as well as mixed-species biofilms of A. niger-S. aureus, over 24 and 48 h. Expression of A. niger biofilm-related genes (eng1, xynB, exo, eglA, eglB, and eglC) was analyzed using real-time polymerase chain reaction (PCR). Impact of S. aureus on the gene expression of A. niger was evaluated and compared to the gene expression of A. niger alone, which served as the control.

Results: Biofilm formation assays showed that A. niger biofilm formation was significantly inhibited when co-cultured with S. aureus, with optical density values dropping from 0.56 (alone) to 0.15 at 24 h and 0.05 at 48 h. Real-time PCR analysis revealed that the expression of A. niger biofilm-related genes, namely eng1, xynB, exo, eglA, eglB, and eglC, increased significantly in single-species biofilms, reaching 2.5, 3, 1.5, 3.5, 2, and 1.7, respectively, at 24 h and 3.5, 4, 2, 4.2, 3, and 2, respectively at 48 h. However, in co-culture with S. aureus, their gene expression was markedly reduced to 0.8, 0.5, 0.4, 0.9, 0.6, 0.5, respectively, at 24 h and 0.5, 1, 0.2, 0.8, 0.6. , and 0.3, respectively, at 48 h, demonstrating a strong inhibitory effect of S. aureus on A. niger biofilm formation and gene expression.

Conclusion: This study described the antagonistic relationship between S. aureus and A. niger on the gene expression biofilm that causes otomycosis, as well as the antibiosis relationship between the two during in vitro biofilm formation. These findings provide new insights into the complex interactions between these microorganisms during infection and may have implications for understanding and managing otomycosis.

Background and purpose: Fungal infections caused by rare pathogens are becoming an increasingly pressing problem in modern healthcare due to the severe course of the disease, high incidence of disability and mortality of patients. To study clinical and laboratory features and treatment of severe fungal infections caused by rare yeast-like pathogens in adult patients.

Materials and methods: The prospective observational non-interventional study (2004-2022) included 310 adult patients with severe fungal infections in the Kashkin Research Institute of Medical Mycology based on North-Western State Medical University named after I.I. Mechnikov, Saint-Petrsburg, Russian Federation (from October 2004 to December 2022). To identify the pathogen, we used direct microscopy, microscopy with calcofluor white, culture isolation from blood and tissue biopsies, cerebrospinal fluid or BAL fluid. Micromycete cultures were identified to species based on morphological characteristics and PCR-test.

Results: We treated 310 adult patients with severe fungal infections -10% of them caused by rare yeast-like pathogens (n=30). Analysis of the data presented a general portrait of the patient: a 30-year-old man who has been in the ICU for more than 14 days (93%). Most often, the pathogen was isolated from the blood or biofilm of the central venous catheter (77%). Isolated damage to organs and tissues (without fungemia) was diagnosed in 23% of patients (involving the central nervous system, lungs and skin). Trichosporon spр. and Rhodotorula spр. were the main pathogens (together - 73%). Despite treatment, mortality remains very high - 37%.

Conclusion: It is necessary to examine the biological substrate from the lesion daily for fungi if there is no effect from standard therapy. It is necessary to perform species identification of the pathogen and determine sensitivity to antimycotics.