Current Medical Mycology最新文献

Background and purpose: Invasive candidiasis (IC) in the hospitalized population is one of the leading causes of invasive fungal infections (IFIs). Microbiological diagnosis of IC suffers due to poor sensitivity of blood culture and relative inaccessibility to more sensitive modalities. (1, 3)-β-D-glucan (BDG) is a cell wall polysaccharide found in a range of fungi. Various commercial assays are available based on various detection techniques. This study aimed to assess the diagnostic performance of the FungiXpert® Fungus BDG Detection Kit by Genobio Pharmaceutical Co. Ltd. (Tianjin, China), based on chemiluminescent method, for diagnosis of candidemia and deep-seated candidiasis.

Materials and methods: In total, 80 patients (34 males and 46 females) were included with a median age of 35 years old. In accordance with EORTC/MSGERC definitions, 39 patients had proven IC. The number of patients within the probable, possible, and no IC (taken as control) groups were 8, 4, and 29, respectively. Blood samples were collected for fungal blood culture and BDG assay.

Results: After exclusion of cases with evidence of concurrent IFI other than IC, median serum BDG was 0.63 ng/ml for proven IC; while it was 0.04 ng/ml for NO IC. Sensitivity, specificity, positive, and negative predictive values were 60.52%, 81.81%, 85.18%, and 54.54%, respectively. Positive likelihood ratio was 3.32. While the assay performed best for Candida tropicalis with median BDG of 1.92 ng/ml and sensitivity of 92.3%, its performance was worst for Candida parapsilosis, with median BDG of 0.04 ng/ml and sensitivity of 44.44%. Overall mortality rate was 65.62% in the BDG positive group, which was significantly higher than that in the BDG negative group (33.33%).

Conclusion: The performance of the FungiXpert® Fungus BDG Detection Kit was acceptable for invasive candidiasis in the present resource-limited setup. The major advantages of this assay were the ease of performance in a semi-automated cartridge format, relatively lower cost per test, non-reliance on glucan-free procedures or instruments and minimal hands-on procedure.

Background and purpose: Onychomycosis is a common fungal infection that affects the nails, caused by various fungal agents. Moreover, yeast onychomycosis has increased in recent years. Yeast isolates might not be identified at the species level by conventional methods, whereas molecular methods can identify yeast isolates more accurately. This study aimed to identify yeast communities isolated from nail specimens by polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) and PCR- fragment size polymorphism (FSP) methods.

Materials and methods: This experimental study was conducted on archival yeast isolates obtained from 269 patients suspected of onychomycosis who referred to the Medical Mycology Laboratory at Shiraz University of Medical Sciences in Shiraz, Iran, between April 2022 and March 2023. Onychomycosis was confirmed through direct examination and culture of nail specimens. The PCR-RFLP and PCR-FSP methods were used to identify yeast isolates.

Results: In total, 78 (28.99%) yeast strains were identified. Candida albicans was the most common species, followed by Candida parapsilosis complex and Candida tropicalis. Uncommon species of yeasts, such as Candida utilis, Candida pararugosa, Candida nivariensis, and Rhodotorula rubra were identified by molecular methods. The PCR-FSP method showed a strong agreement with the PCR-RFLP method in the identification of common yeast agents causing onychomycosis (κ=0.84).

Conclusion: It seems necessary to use molecular diagnostic tools in addition to conventional methods to identify yeast isolates in clinical laboratories. The rapid and accurate identification of fungal agents causing onychomycosis is useful for the selection of an appropriate treatment strategy.

Background and purpose: Candida utilis is a recently emerging nosocomial fungal pathogen. Candidemia is the fourth most prevalent cause of bloodstream Infections with mortality rates varying from 5-71%.

Materials and methods: This was a retrospective study conducted at Uttar Pradesh University of Medical Sciences, Etawah, India, from September 2023 to February 2024. Rapid identification was performed by VITEK® 2 (BioMérieux, France) and 18 out of 20 C. utilis cases were verified by matrix assisted laser desorption ionization-time of flight mass spectrometry (BioMerieux, France). Susceptibility testing was conducted by VITEK® 2 appropriate Card.

Results: Candida utilis was mainly observed between 0-9-month-old neonates, except one case of 11 years old. The extended Intensive Care Unit stay and prior antibiotic use were common risk factors in all cases. They were pan susceptible to each of the tested antifungal medications, and 6 out of 10 cases showed positive clinical response after antifungal treatment.

Conclusion: Early identification and prompt treatment favors a good clinical outcome. The current research primarily aimed to elaborate on the speciation, incidence, and antifungal susceptibility testing of C. utilis at a tertiary care center.

Background and purposes: The fungi known as dermatophytes are a group of keratinophilic agents responsible for superficial infections in humans and animals. Recognition of the species distribution and epidemiology of dermatophytosis may be helpful in the prevention and improve prophylactic measures. The present molecular epidemiology study sought to investigate the incidence of etiological agents causing dermatophytosis.

Materials and methods: The morphologic methods and polymerase chain reaction-restriction fragment length polymorphism using MvaI restriction enzyme were performed to identify dermatophytes isolated from the soil, compost, and clinical samples.

Results: Based on findings, 39 (8.1%) clinical specimens and 10 (8.2%) environmental samples were morphologically and molecularly identified as dermatophytes. In the clinical samples, Trichophyton mentagrophytes/T. interdigitale species complex was isolated with the highest incidence rate. The dermatophytes comprise seven species of the four genera, viz., T. interdigitale (currently T. mentagrophytes, n=15, 40.5%), Microsporum canis (n=10, 27%), T. verrucosum (n=5, 13.5%), T. rubrum (n=4, 10.8%), Myriodontium keratinophilum (n=2, 5.4%), and T. benhamiae (n=1, 2.7%). The geophilic identified species included Nannizzia gypsea (n=5), Arthroderma multifidum (n=2), Afanoascus flavisence (n=2), and Nannizzia fulva (n=1).

Conclusion: The current study provides a diverse overview of dermatophytes in the northwest of Iran to improve their surveillance. The present investigation of clinical specimens revealed that Myriodontium keratinophilum, as a species rarely detected with keratolytic properties, emerged as a causative agent of dermatophytosis.

Background and purpose: Candida infections in India have shifted, with an increase in the incidence rate of invasive candidiasis, particularly due to non-albicans species. The central nervous system infections by Candida glabrata are sparsely reported and more understanding and research is needed regarding these infections.

Case report: This study reported an unusual case of C. glabrata meningitis in a middle-aged female with pulmonary tuberculosis and newly diagnosed acquired immunodeficiency syndrome with a low cluster of differentiation 4 count (12 cells/mm³). Initially, the patient was treated with fluconazole. Subsequently, the patient underwent therapy involving amphotericin B and flucytosine. The cerebrospinal fluid cultures eventually grew C. glabrata, confirmed by matrix-assisted laser desorption ionization time-of-flight analysis. Despite switching to amphotericin B and flucytosine, the conditions of the patient deteriorated, leading to her death.

Conclusion: Candida glabrata candidemia requires meticulous and vigilant management due to its high mortality rate and relatively higher resistance to azoles, particularly fluconazole. This case underscored the severe and pressing challenges in the management of C. glabrata meningitis, particularly in immunocompromised patients.

Background and purpose: Dorema species are well-known antifungal medicinal plants. Dorema kopetdaghense (Apiaceae family) is a rarely investigated plant endemic to Iran. The present study aimed to assess the antifungal, antibacterial, antioxidant, and cytotoxic activities of root extracts of different plants.

Materials and methods: The methanolic crude extract (MeOH) and its sub-fractions, including petroleum ether (PE), dichloromethane (DCM), ethyl acetate (EtOAc), and n-butanol (n-BuOH) were prepared.

Results: Results from the antifungal and antibacterial activities of fractions indicated remarkable antifungal effects against Candida albicans with minimum inhibitory concentration and minimum bactericidal concentration values of 10 µg/mL; however, no cytotoxicity was observed in the case of selected cancer cells. Moreover, methanolic soluble fractions showed good antiradical effects evaluated via DPPH and β-carotene bleaching tests possessing half-maximal inhibitory concentration (IC₅₀) of 20.11 and 41.32 µg/mL, respectively, though it was less effective than positive controls ascorbic acid (8.47 and 31.71 µg/mL, respectively) and butylated hydroxytoluene (IC₅₀: 10.29 and 33.55 µg/mL, respectively).

Conclusion: It can be concluded that strong antifungal and antioxidant activities without notable cytotoxicity, suggest the potential safety of the plant to be used as a natural antifungal remedy as well as a preservative in the food industry.

Background and purpose: Candida parapsilosis is the third most commonly isolated species from candidemia patients admitted to Indian intensive care units. Outbreak of infection and emergence of fluconazole resistance associated with this particular species has been increasingly documented since 2018. Worldwide data has documented that Y132F substitution in the ERG11 gene is the predominant fluconazole resistance mechanism among C parapsilosis. Hence, this study aimed to detect fluconazole resistance by targeting Y132F mutation in the ERG11 gene in C. parapsilosis, by conventional polymerase chain reaction (PCR) assay with in-house designed primers.

Materials and methods: A total of 75 Candida isolates were collected from candidemia patients (Jan-Dec 2023). All the Candida isolates were subjected to phenotypic and genotypic characterization. PCR-restriction fragment length polymorphism was performed for identification and confirmation of C. parapsilosis isolates. The antifungal susceptibility testing by broth microdilution method was performed according to the Clinical and Laboratory Standards Institute guidelines (M27-A3) for all C. parapsilosis against fluconazole, itraconazole, voriconazole, and posaconazole to determine their minimum inhibitory concentration (MIC) values. Candida parapsilosis-specific PCR assay was developed with in-house designed primers to detect Y132F mutation in the ERG11 gene.

Results: In this study, among 75 candidemia patients (Jan-Dec 2023), about 24% of the candidemia was caused by C. parapsilosis. Fluconazole resistance among C. parapsilosis was found to be 16.7% with a MIC range of 32-64 µg/ml. The PCR assay successfully identified all three fluconazole-resistant C. parapsilosis with Y132F mutation, thereby confirming the PCR results. Furthermore, validation of the presence and absence of Y132F mutation in resistant and susceptible isolates by DNA sequencing showed that the results were in concordance with our PCR assay.

Conclusion: The developed PCR assay successfully detected the Y132F mutation within 3 h. This assay can be useful for early detection of fluconazole-resistant C. parapsilosis isolates in candidemia patients, which helps the provision of early antifungal treatment for better patient management.

Background and purpose: Cryptococcus neoformans and Cryptococcus gattii are highly virulent species that cause diseases, such as meningoencephalitis and pulmonary infections. The CAP59 gene predominantly determines the virulence of the pathogenic species. This study aimed to examine CAP59 in both pathogenic and non-pathogenic species.

Materials and methods: This study identified Cryptococcus species through extensive literature, retrieved sequences from UniProt, explored protein families utilizing InterPro, motif analysis by MEME, multiple sequence alignment using Clustal Omega, performance of the phylogenetic analysis with MEGA, modeled protein structures with MODELLER, and separately visualized pathogenic and non-pathogenic structures in PyMOL.

Results: Motif analysis showed four conserved regions between the pathogenic and non-pathogenic sequences. Moreover, multiple sequence alignment revealed that pathogenic CAP59 gene sequences lacked a significant portion, compared to non-pathogenic ones, with several mutations in the gene sequence of pathogenic species CAP59 at highly conserved regions. The phylogenetic analysis and pairwise distance matrix revealed that Cryptococcus amylolentus is closely related to pathogenic species. Predicted CAP59 protein structures were superimposed to show structural differences between pathogenic and non-pathogenic species.

Conclusion: In conclusion, the results suggested that non-pathogenic species may have evolved into pathogenic species since the CAP59 gene sequences of the non-virulent species were longer than those of the virulent species sequences. It implies that the virulent sequences may have lost that region at some point in evolution, which additional research on capsule formation-related genes can further corroborate.

Background and purpose: Plants are crucial habitats for fungus communities as they provide an appropriate physical environment for the growth and reproduction of the yeast microbiome. Varieties of pathogenic and non-pathogenic yeast could be found in Eucalyptus trees. Although Cryptococcus species are the most common pathogenic yeasts associated with Eucalyptus trees, other yeasts also grow on trees and are critical to human health. This study aimed to identify the yeast species associated with Eucalyptus trees.

Materials and methods: In total, 107 yeast species were collected from Eucalyptus trees and subsequently identified through both molecular and traditional techniques. Genomic DNA extraction was performed using the boiling method. The internal transcribed spacer region of the ribosomal DNA was amplified utilizing the polymerase chain reaction (PCR) technique, followed by the purification and sequencing of the PCR products to identify the isolates.

Results: Yeast strains belonged to 12 genera and 26 species of both the Ascomycete and Basidiomycete phyla. The most frequent species were Rhodotorula mucilaginosa (24.2%), Candida tropicalis (15%), Candida guilliermondii (11.2%), and Aureobasidium pullulans (10.2%).

Conclusion: In this study, most of the yeast isolates, such as Candida and Trichosporon, were important to human health. Eucalyptus trees, as part of the natural flora, could be considered an environmental reservoir for yeasts, in which they can survive, disperse to the surrounding environment, and become a potential infectious source affecting public health.

Background and purpose: The three most common causes of vaginitis are bacteria, yeast, and Protozoa. Candida albicans is one of the most common causes of vaginitis and commonly affects millions of females with different signs and symptoms. Secretion of exoenzymes from Candida species plays an important role in virulence and pathogenesis. Increasing our knowledge about the pathogenesis of candidiasis could help to design new anti-Candida drugs. This study aimed to evaluate the phospholipase, esterase, and hemolysin activities of the vaginal Candida isolates and their correlation with the presence of vulvovaginal candidiasis.

Materials and methods: In total, 119 Candida albicans isolates from vaginal candidiasis were enrolled in the study. Egg yolk agar, Tween 80 opacity medium, and blood agar plate assays were used for the determination of phospholipase, esterase, and hemolytic activities, respectively.

Results: Based on the findings, 110 (92.44%) isolates showed phospholipase activity, 93 (78.2%) isolates were esterase producers, and 90 (75.6%) species had hemolytic activity.

Conclusion: This study showed that most of the tested isolates had different enzymatic patterns. Discrimination of variations in the production of these exoenzymes among different Candida isolates may depend on Candida spp. pathogenicity and could be responsible for the severity of symptoms among the patients.