Phenotypic characterization and adhesive properties of vaginal Candida spp. strains provided by the CHU Farhat Hached (Sousse, Tunisia)

Biochemical typing and evaluation of pathogenicity in vulvovaginal isolates of Candida albicans complex

Introduction

Candida albicans, C. dubliniensis, and C. africana form the Candida albicans complex.

Objective

To identify the phenotypic and pathogenic characteristics of isolates of the C. albicans complex preserved in a collection.

Materials and methods

Three hundred presumptive strains of the C. albicans complex were evaluated using CHROMagarTM Candida. Germ tube production was determined by three methods, chlamydospores formation was assessed and colonies were characterized in artisanal agars (Rosmarinus officinalis and Nicotiana tabacum). MALDI-TOF was used as the gold standard identification test. To detect pathogenicity factors, we evaluated the hemolytic activity of each isolate and cocultured with Staphylococcus aureus, coagulase enzyme production, and biofilm formation.

Results

Out of the 300 isolates, 43.7% produced germ tube in the heart-brain infusion broth and 47% of the isolates produced chlamydospores. In the artisan media, 6% of the isolates produced brown colonies on rosemary agar and 5% did so on tobacco agar. None of the strains hemolyzed the blood agar alone or cocultured with S. aureus. However, 50% of the isolates hemolyzed the potato dextrose agar supplemented with blood. All strains were coagulase producers, and biofilm production was variable. For germ tube production, the human serum method showed the same positivity as the milk broth method. All isolates were identified as C. albicans by MALDI-TOF.

Conclusions

The use of proteomics, molecular tests or a combination of methods is required for species identification.

Efficacy of Extracts of Cyanthillium Cinereum, Khaya senegalensis and Lippia multiflora on Candida Strains Isolated From Urine Samples in Benin (West Africa)

The search for new bioactive molecules with antifungal properties to combat resistance to classical antifungals represents a great challenge. This study aimed to explore the virulence factors and resistance profile of Candida species isolated from urine samples in Benin and the in vitro efficacy of organic extracts of Cyanthillium cinereum (L.) H.Rob., Lippia multiflora Moldenke and Khaya senegalensis (Desv.) A.Juss. on the growth of these Candida spp. The study focused on Candida strains isolated from urine samples collected from patients admitted to the bacteriological analysis laboratories of hospitals in Southern Benin. The sensitivity of these strains to classical antifungal agents was determined by the simple diffusion method. Their pathogenicity was investigated via several virulence factors (gelatinase, hemolysin, hydrophobicity, adhesin, biofilm and lecithinase). The in vitro efficacy of the aqueous, ethanolic and hydro-ethanolic extracts of the plants on Candida albicans ATCC 90028 and on six clinical strains was evaluated by the method of determination of the inhibition diameters. The results obtained showed that 51 different Candida strains were isolated from the collected urine samples with a respective predominance of Candida albicans (52.94%) and Candida glabrata (17.64%) species. All identified species were sensitive to amphotericin B and nystatin but 20% are resistant to fluconazole and present 15 different resistance profiles. Six different virulence factors were identified with a high frequency of hydrophobicity (96.08%) and adhesin (94.12%). Antifungal tests revealed that at 100 mg/mL the plant extracts were active on the tested strains with better activity for Cyanthilium cinereum and Khaya senegalensis. Cyanthilium cinereum, Khaya senegalensis and Lippia multiflora showed antifungal activity on virulent Candida strains suggesting the possibility to explore them further for the discovery of new antifungal molecules.

Current Aspects in the Biology, Pathogeny, and Treatment of Candida krusei, a Neglected Fungal Pathogen

Fungal infections represent a constant and growing menace to human health, because of the emergence of new species as causative agents of diseases and the increment of antifungal drug resistance. Candidiasis is one of the most common fungal infections in humans and is associated with a high mortality rate when the fungi infect deep-seated organs. Candida krusei belongs to the group of candidiasis etiological agents, and although it is not isolated as frequently as other Candida species, the infections caused by this organism are of special relevance in the clinical setting because of its intrinsic resistance to fluconazole. Here, we offer a thorough revision of the current literature dealing with this organism and the caused disease, focusing on its biological aspects, the host-fungus interaction, the diagnosis, and the infection treatment. Of particular relevance, we provide the most recent genomic information, including the gene prediction of some putative virulence factors, like proteases, adhesins, regulators of biofilm formation and dimorphism. Moreover, C. krusei veterinary aspects and the exploration of natural products with anti-C. krusei activity are also included.