Genotyping and Drug Resistance Profile of Clinical Isolates of Candida albicans from Vulvovaginal Candidiasis in the Eastern China

ATR-FTIR spectroscopic markers indicating drug resistance in selected Candida strains

The rising incidence of fungal infections and the increasing prevalence of antifungal resistance highlight the need for rapid and reliable diagnostic methods. This study investigates the potential of ATR-FTIR spectroscopy to identify spectroscopic markers of drug resistance in selected Candida strains. In this pilot study, ATR-FTIR spectroscopy was employed to analyse the biochemical composition of Candida albicans, Candida glabrata and Candida dubliniensis isolates. The minimum inhibitory concentrations (MIC) of antifungals were determined using antifungals concentration gradient strips, and the spectral data were processed to identify differences between resistant and sensitive isolates. Based on the results for Candida albicans, Candida glabrata and Candida dubliniensis, specific ATR-FITR spectroscopic markers of drug resistance were identified, which highlighted the necessity for these markers to be antifungal-specific. Despite the limitations of the study, the findings underscore the potential of ATR-FTIR spectroscopy in identifying spectroscopic markers of antifungal resistance. These preliminary results provide a foundation for further research, which could lead to the development of rapid diagnostic tools for detecting drug-resistant Candida strains, thereby improving the management and treatment of fungal infections.

Molecular epidemiology and antifungal susceptibility of dermatophytes and Candida isolates in superficial fungal infections at a grade A tertiary hospital in Northern China

This study analyzed the prevalence and antifungal susceptibility of superficial fungal infections in 295 cases from 2019 to 2020 at a dermatology clinic. Dermatophytes were the predominant pathogens (69.5%), including Trichophytonrubrum, T. interdigitale, Microsporum canis, et al., followed by Candida spp. (29.5%), including Candidaalbicans, Ca. parapsilosis, and Ca. glabrata. The most common infections were onychomycosis (36.3%), tinea cruris (30.5%), and tinea corporis (18.6%). The distribution of SFI types showed variations based on gender, age, and season. Common antifungal agents, including terbinafine, voriconazole, ciclopiroxamine, amphotericin B, itraconazole, and ketoconazole have exhibited low minimum inhibitory concentrations against dermatophytes, especially terbinafine, which has been potent against superficial fungal infections caused by dermatophytes in the local area. Candida spp. strains were generally susceptible or classified as wild-type to 5-flucytosine and amphotericin B, with 92.0% being wild-type for itraconazole. However, resistance to fluconazole and voriconazole was observed in a small percentage of Ca. albicans and Ca. parapsilosis strains. The emergence of drug-resistant Candida underscores the importance of prudent antifungal use and continuous surveillance.

Heterologous expression of the insect SVWC peptide WHIS1 inhibits Candida albicans invasion into A549 and HeLa epithelial cells

Candida albicans (C. albicans), a microbe commonly isolated from Candida vaginitis patients with vaginal tract infections, transforms from yeast to hyphae and produces many toxins, adhesins, and invasins, as well as C. albicans biofilms resistant to antifungal antibiotic treatment. Effective agents against this pathogen are urgently needed. Antimicrobial peptides (AMPs) have been used to cure inflammation and infectious diseases. In this study, we isolated whole housefly larvae insect SVWC peptide 1 (WHIS1), a novel insect single von Willebrand factor C-domain protein (SVWC) peptide from whole housefly larvae. The expression pattern of WHIS1 showed a response to the stimulation of C. albicans. In contrast to other SVWC members, which function as antiviral peptides, interferon (IFN) analogs or pathogen recognition receptors (PRRs), which are the prokaryotically expressed MdWHIS1 protein, inhibit the growth of C. albicans. Eukaryotic heterologous expression of WHIS1 inhibited C. albicans invasion into A549 and HeLa cells. The heterologous expression of WHIS1 clearly inhibited hyphal formation both extracellularly and intracellularly. Furthermore, the mechanism of WHIS1 has demonstrated that it downregulates all key hyphal formation factors (ALS1, ALS3, ALS5, ECE1, HWP1, HGC1, EFG1, and ZAP1) both extracellularly and intracellularly. These data showed that heterologously expressed WHIS1 inhibits C. albicans invasion into epithelial cells by affecting hyphal formation and adhesion factor-related gene expression. These findings provide new potential drug candidates for treating C. albicans infection.

Berberine inhibits Candida albicans growth by disrupting mitochondrial function through the reduction of iron absorption

AIMS

This study aimed to investigate whether berberine (BBR) can inhibit the iron reduction mechanism of Candida albicans, lowering the iron uptake of the yeast and perhaps having antimicrobial effects.

METHODS AND RESULTS

We determined that BBR may cause extensive transcriptional remodeling in C. albicans and that iron permease Ftr1 played a crucial role in this process through eukaryotic transcriptome sequencing. Mechanistic research showed that BBR might selectively inhibit the iron reduction pathway to lower the uptake of exogenous iron ions, inhibiting C. albicans from growing and metabolizing. Subsequent research revealed that BBR caused significant mitochondrial dysfunction, which triggered the process of mitochondrial autophagy. Moreover, we discovered that C. albicans redox homeostasis, susceptibility to antifungal drugs, and hyphal growth are all impacted by the suppression of this mechanism by BBR.

CONCLUSIONS

The iron reduction mechanism in C. albicans is disrupted by BBR, which disrupts mitochondrial function and inhibits fungal growth. These findings highlight the potential promise of BBR in antifungal applications.

High diversity of yeast species and strains responsible for vulvovaginal candidiasis in South-East Gabon

OBJECTIVES

Candida albicans generally remains the principal pathogenic yeast responsible for vulvovaginal candidiasis (VVC), although with variable prevalence. In this study, we evaluated the evolution of the prevalence of the non-Candida albicans Candida (NCAC) species and investigated the genotypic diversity and the population genetic structure of the circulating C. albicans strains associated with VVC in the vicinity of Franceville (Gabon).

METHODS

A total of 110 independent isolates were identified using both MALDI-TOF MS and conventional techniques. The population genetic structure of the C. albicans strains was determined by multiple locus variable-number tandem repeat analysis using 4 microsatellite markers.

RESULTS

The mean and median age of the patients was 31 years. Seven patients had a mixed infection. C. albicans accounted for 62 % (n=68) of the total isolates. NCAC were dominated by C. glabrata, followed by P. kudriavzevii, C. parapsilosis, C. tropicalis, M. guilliermondii, and C. nivariensis. The cluster analysis revealed a high diversity, with a total of 50 different genotypes. The most represented genotype was shared by only four strains, while the vast majority (39 strains) had a unique MLVA pattern. Geographic clusters were not detected.

CONCLUSION

The study provides information on species distribution and possible changing epidemiology while reporting for the first time C. nivariensis in VVC in Africa. This study is also the first to investigate the genotypic diversity of the circulating C. albicans strains associated with VVC in Central Africa. Such analyses would help understand the molecular epidemiology of C. albicans.

Candida albicans Multilocus Sequence Typing Clade I Contributes to the Clinical Phenotype of Vulvovaginal Candidiasis Patients

Candida albicans is the most frequent fungal species responsible for vulvovaginal candidiasis (VVC), which exhibits distinct genetic diversity that is linked with the clinical phenotype. This study aimed to assess the genotypes and clinical characteristics of different C. albicans isolates from VVC patients. Based on multilocus sequence typing (MLST), clade 1 was identified as the largest C. albicans group, which appeared most frequently in recurrent VVC and treatment failure cases. Further study of antifungal susceptibility demonstrated that MLST clade 1 strains presented significantly higher drug resistance ability than non-clade 1 strains, which result from the overexpression of MDR1. The mRNA and protein expression levels of virulence-related genes were also significantly higher in clade 1 isolates than in non-clade 1 isolates. Proteomic analysis indicated that the protein stabilization pathway was significantly enriched in clade 1 strains and that RPS4 was a central regulator of proteins involved in stress resistance, adherence, and DNA repair, which all contribute to the resistance and virulence of MLST clade 1 strains. This study was the first attempt to compare the correlation mechanisms between C. albicans MLST clade 1 and non-clade 1 strains and the clinical phenotype, which is of great significance for VVC classification and treatment.