Surface, adhesiveness and virulence aspects of Candida haemulonii species complex

Area of Science:

• Mycology
• Medical Microbiology
• Pathogen Biology

Background:

• The Candida haemulonii complex (Ch, Cd, Chv) comprises opportunistic fungal pathogens with inherent antifungal resistance.
• Limited knowledge exists regarding the specific biology and virulence factors of these emerging pathogens.

Purpose of the Study:

• To investigate the surface properties of clinical isolates of the Candida haemulonii complex.
• To evaluate the virulence potential of these isolates in murine macrophages and Galleria mellonella larvae.

Main Methods:

• Scanning electron microscopy was used to examine yeast morphology and surface characteristics.
• Cell surface hydrophobicity, charge, and glycoconjugate composition (mannose/glucose, N-acetylglucosamine, sialic acid) were analyzed.
• Chitin content, sterol/lipid composition, and adherence to various surfaces were assessed.
• Virulence was tested using murine macrophages and Galleria mellonella infection models.

Main Results:

• All Candida haemulonii complex species displayed oval yeast morphology with surface irregularities and aggregate formation.
• Cell surface hydrophobicity varied among isolates, with negative surface charges predominating.
• Significant amounts of mannose/glucose and N-acetylglucosamine glycoconjugates were detected; sialic acid was poorly expressed.
• Candida duobushaemulonii isolates showed higher chitin content compared to other species.
• Isolates adhered to polystyrene, poly-L-lysine-coated glass, and glass surfaces, and interacted similarly with murine macrophages.
• The Candida haemulonii complex demonstrated significant virulence, killing at least 80% of Galleria mellonella larvae within 120 hours.

Conclusions:

• The Candida haemulonii complex exhibits diverse surface properties that may contribute to virulence.
• Surface-related attributes play a role in the infectious process of these antifungal-resistant opportunistic pathogens.