Up-Regulation of Antimicrobial Peptides Gallerimycin and Galiomicin in Galleria mellonella Infected with Candida Yeasts Displaying Different Virulence Traits.

Galleria mellonella has been described as a cheap and an easy-to-reproduce model for the study of fungal infections. We hypothesized that yeasts with higher virulence potential decrease survival and significantly trigger an immune response in G. mellonella through the regulation of innate immunity-related genes encoding antimicrobial peptides (AMPs) such as gallerimycin and galiomicin. Candida albicans SC5314 and Candida dubliniensis CBS 7987, selected because of their different virulence potential, were used for a killing assay followed by the determination of gene expression using qPCR. In vivo results confirmed a significantly (p = 0.0321) lower pathogenicity for C. dubliniensis than for C. albicans. Accordingly, the induction of C. dubliniensis AMPs was lower at all the selected time points post-infection (1 h, 24 h, 48 h). Moreover, we observed an extremely high regulation of the galiomicin gene compared to the gallerimycin one, suggesting a different role of the tested AMPs in protecting G. mellonella from candidiasis.

Anti-biofilm activity of antibody directed against surface antigen complement receptor 3-related protein-comparison of Candida albicans and Candida dubliniensis.

Candida albicans and C. dubliniensis are related yeasts that differ in the expression of virulence-associated proteins involved in adherence and biofilm development. CR3-RP (complement receptor 3-related protein) is one of the surface antigens expressed by Candida species. The main objective of this research was to elucidate the effect of the polyclonal anti-CR3-RP antibody (Ab) on adherence and the biofilm formed by C. albicans SC5314 and C. dubliniensis CBS 7987 and two clinical isolates in vitro, ex vivo and in vivo. A comparison of species, and of treated vs. non-treated with the anti-CR3-RP Ab showed a reduction in adherence (22%-41%) that was dependent on the time point of evaluation (60, 90 or 120 min), but did not prove to be species-dependent. Confocal microscopy revealed a decreased thickness in biofilms formed by both species after pre-treatment with the anti-CR3-RP Ab. This observation was confirmed ex vivo by immunohistochemistry analysis of biofilms formed on mouse tongues. Moreover, anti-CR3-RP Ab administration, 1 h post-infection, has been shown to promote larval survival compared to the control group in a Galleria mellonella infection model. Our data suggest a potential activity of the anti-CR3-RP Ab relevant to immunotherapy or vaccine development against biofilm-associated Candida infections.

Effectiveness of the Photoactive Dye Methylene Blue versus Caspofungin on the Candida parapsilosis Biofilm in vitro and ex vivo.

This research studied the effectiveness of the photoactive compound methylene blue (MB) activated with red LED light (576-672 nm) compared to that of caspofungin (CAS) on 1 Candida albicans and 3 Candida parapsilosis strains. Results were evaluated in terms of SMIC50 for CAS or in PDI (photodynamic inactivation)-SMIC50 for MB (minimal inhibitory concentration inhibiting sessile biofilm to 50% in comparison to the control without CAS or after irradiation in comparison to the control without MB). While all strains were susceptible to CAS in planktonic form, the SMIC50 was determined to be >16 µg mL(-1) when CAS was added to a 24 h biofilm. However, PDI-MIC50s (1.67 mW cm(-2) , fluence 15 J cm(-2) ) were 0.0075-0.03 mmol L(-1) . For biofilm, PDI-SMIC50s were in the range from 0.7 to 1.35 mmol L(-1) . MB concentration of 1 mmol L(-1) prevented a biofilm being formed ex vivo on mouse tongues after irradiation regardless of the application time, in contrast to CAS, which was only effective at a concentration of 16 µg mL(-1) when it was added at the beginning of biofilm formation. PDI seems to be a promising method for the prevention of microbial biofilms that do not respond significantly to conventional drugs.

First case of systemic phaeohyphomycosis due to Cladophialophora bantiana in Slovakia.

INTRODUCTION: Melanized or dematiaceous fungi are associated with a wide variety of infectious syndromes. Cladophialophora bantiana is one of the most common and dangerous neurotropic fungi, able to cause brain abscess and disseminated infection. CASE PRESENTATION: We report a new case of phaeohyphomycosis brain abscesses caused by C. bantiana in Slovakia. The patient was a 63-year-old man having undergone heart transplantation, with dyspnoea, left-sided bronchopneumonia and fevers. CT (computed tomography) and MRI (magnetic resonance imaging) of the brain revealed numerous abscesses. Bacterial infection was proven by neither the growth of bacteria in culture nor the presence of bacterial antigens. Direct microscopy of the pus from the brain abscess showed Gram-positive hyphae. The isolate was finally identified as C. bantiana based on morphological and physiological features, and on DNA sequence analysis. CONCLUSION: In spite of appropriate therapy, neurological complications and accelerated respiratory insufficiency resulted in the patient's death. Concerning clinical manifestation of the brain phaeohyphomycosis that can sometimes be a problem to distinguish from malignancy, physicians should also assume infection caused by this serious pathogen.