Species distribution and antifungal susceptibility profiles of yeasts isolated from onychomycosis: a cross-sectional study with insights into emerging species.

Candida onychomycosis is a common fungal infection affecting the nails, primarily caused by Candida (C.) species. Regarding the increasing trend of Candida onychomycosis and the antifungal resistant phenomenon in recent years, this study aims to evaluate the epidemiological characteristics of Candida onychomycosis, the distribution of emerging species, and the antifungal susceptibility profiles of isolates. Onychomycosis caused by yeast species was confirmed through direct examination and culture of nail scraping among all individuals suspected to have onychomycosis and referred to a medical mycology laboratory between June 2019 and March 2022. Species of yeast isolates were identified using the multiplex PCR and PCR-RFLP methods. The antifungal susceptibility of isolates to common antifungal agents and imidazole drugs was evaluated according to the M-27-A3 CLSI protocol. Among 101 yeast strains isolated from onychomycosis, Candida parapsilosis complex (50.49%) was the most common species, followed by C. albicans (20.79%) and C. tropicalis (10.89%). Rare species of yeasts such as C. guilliermondii and Saccharomyces cerevisiae were also identified by molecular methods. Results obtained from antifungal susceptibility testing showed significant differences in MIC values of isoconazole, fenticonazole, and sertaconazole among different species. Overall, a fluconazole-resistant rate of 3% was found among Candida species. Moreover, there was a statistically significant difference in MICs of fenticonazole and clotrimazole between the two most prevalent causative species, C. parapsilosis complex and C. albicans. Correct identification of the causative agents of onychomycosis and performing susceptibility testing could be helpful in choosing the most appropriate antifungal therapy.

In vitro activity of 23 antifungal drugs against 54 clinical and environmental Aspergillus oryzae isolates.

The treatment of invasive aspergillosis caused by cryptic species remains a challenge due to the lack of randomised clinical trials and investigation of the efficacy and safety of different therapeutic strategies. We aimed to evaluate the in vitro activity of 23 conventional and new antifungal drugs against 54 clinical and environmental Aspergillus oryzae isolates by using the Clinical and Laboratory Standards Institute (CLSI) standard M38-A3. The lowest geometric mean MIC values were found for luliconazole and lanoconazole (0.001 µg/ml), followed by anidulafungin (0.104 µg/ml), posaconazole (0.15 µg/ml), itraconazole (0.37 µg/ml), efinaconazole (0.5 µg/ml), voriconazole (0.51 µg/ml), tavaborole (0.72 µg/ml), and amphotericin B (0.79 µg/ml). In contrast, ketoconazole, terbinafine, econazole, tioconazole, ravuconazole, miconazole, nystatin, clotrimazole, griseofulvin, sertaconazole, natamycin, tolnaftate, and fluconazole had no or low activity. Further studies are required to determine how well this in vitro activity translates into in vivo efficacy.

Development of RFLP method for rapid differentiation of Aspergillus flavus and Aspergillus oryzae, two species with high importance in clinical and food microbiology.

Aspergillus flavus and Aspergillus oryzae, two species of Aspergillus section Flavi, are of utmost significance in health, medicine, biotechnology, and foods industries. The methods currently used in mycology for the discrimination of these two closely related species were unable to definitively and rapidly distinguish. The present study aimed to develop a restriction fragment length polymorphism (RFLP) test based on the cyp51A gene to discriminate between A. flavus and A. oryzae. The cyp51A gene sequences of A. flavus and A. oryzae reference strains were amplified using the specific primers CYP51AF and CYP51AR. The polymerase chain reaction (PCR) products were subjected to digestion with a restriction enzyme, HincII. The polymerase chain reaction (PCR)- RFLP test created specific patterns for standard strains, as well as clinical and environmental A. flavus and A. oryzae isolates. The one-enzyme PCR-RFLP test on the cyp51A gene designed in the present study is a remarkably simple, reliable, and low-cost method for the accurate and rapid differentiation of A. flavus and A. oryzae isolated from clinical and environmental samples.

Echinocandin resistance in Candida parapsilosis sensu stricto: Role of alterations in CHS3, FKS1 and Rho gene expression.

OBJECTIVES: The rate of resistance of Candida parapsilosis to echinocandins remains unexplored in Iran. The main aims of this study were to investigate the susceptibility patterns and possible mechanisms of echinocandin resistance in echinocandin-resistant clinical C. parapsilosis isolates in Iran. METHODS: A total of 105 isolates of C. parapsilosis sensu stricto underwent antifungal susceptibility testing to echinocandins by the broth microdilution reference method. Sequences of the CpERG3 and CpFKS1 genes were analysed using MEGA6 software, and alterations in CHS3, FKS1 and Rho gene expression were evaluated by quantitative reverse transcription (RT-qPCR). REST® software was used to analyse the results. RESULTS: The rate of echinocandin cross-resistance was 2.9% (3/105). No substitutions were detected in Fks1p except for the naturally occurring P660A amino acid substitution observed in isolates both with high and low minimum inhibitory concentrations (MICs). Moreover, the G111R amino acid substitution was not found in Erg3p. Following echinocandin exposure, expression of Rho and FKS1 genes was significantly increased in resistant isolates, whilst the CHS3 gene showed no change. CONCLUSION: Alterations in the expression of some key genes may be responsible for echinocandin resistance among C. parapsilosis isolates. Understanding the mechanisms responsible for drug resistance in C. parapsilosis is not only crucial for the development of new antifungals but is also important in choosing appropriate antifungals for patient treatment at the earliest stage.

Genetic characterization of Toxoplasma gondii in Iranian HIV positive patients using multilocus nested-PCR-RFLP method.

The aim of the present study was to investigate the prevalence and genotyping of Toxoplasma gondii in Iranian human immunodeficiency virus (HIV)-positive patients using multilocus-nested polymerase chain reaction restriction fragment length polymorphism (Mn-PCR-RFLP). A total of 102 serum samples obtained from infected patients were collected from the laboratory centres in northern Iran. Anti-T. gondii antibodies and deoxyribonucleic acid (DNA) detection were accomplished by an enzyme-linked immunosorbent assay and PCR. The Mn-PCR-RFLP method was used for the genotyping of T. gondii. Overall, 68.6% (70/102) and 11.7% (12/102) of the individuals were tested positive for anti-T. gondii immunoglobulin G and T. gondii DNA, respectively. Complete genotyping was performed on 10/12 (83.3%) PCR-positive samples. Accordingly, the samples were classified as genotype #1 (type II clonal; n = 3, 30%), genotype #2 (type III clonal; n = 2, 20%), genotype #10 (type I clonal; n = 2, 20%), genotype #27 (type I variant; n = 1, 10%), genotype #35 (type I variant; n = 1, 10%) and genotype #48 (type III variant; n = 1, 10%). The results were indicative of the high frequency of the type I and type I variant of T. gondii strains in HIV-positive patients in northern Iran. Given the high prevalence of T. gondii and frequency of pathogenic types (pathogen in laboratory mice) in the patients, special measures should be taken to prevent the possible increased incidence of encephalitis by T. gondii.

Low In Vitro Antifungal Activity of Tavaborole against Yeasts and Molds from Onychomycosis.

The in vitro activity of tavaborole, an FDA-approved antifungal drug, was compared to that of four antifungal agents against 170 clinical fungal isolates originating from patients with onychomycosis. Tavaborole had low activity against all isolates compared to itraconazole, terbinafine, and fluconazole, the principal choices for treatment of onychomycosis. Thus, it appears that tavaborole is not a candidate for the treatment of onychomycosis due to Candida species, Aspergillus species, and dermatophytes.