scholarly journals Geometrical Distribution of Cryptococcus neoformans Mediates Flower-Like Biofilm Development

2017 ◽  
Vol 8 ◽  
Author(s):  
William Lopes ◽  
Mendeli H. Vainstein ◽  
Glauber R. De Sousa Araujo ◽  
Susana Frases ◽  
Charley C. Staats ◽  
...  
Keyword(s):  
Cryptococcus Neoformans ◽  
Geometrical Distribution ◽  
Biofilm Development

scholarly journals Cryptococcus neoformans Biofilm Formation Depends on Surface Support and Carbon Source and Reduces Fungal Cell Susceptibility to Heat, Cold, and UV Light

2007 ◽  
Vol 73 (14) ◽  
pp. 4592-4601 ◽  
Author(s):  
Luis R. Martinez ◽  
Arturo Casadevall
Keyword(s):  
Cryptococcus Neoformans ◽  
Biofilm Formation ◽  
Capsular Polysaccharide ◽  
Uv Light ◽  
Surface Characteristics ◽  
Extracellular Polysaccharide ◽  
Microtiter Plate ◽  
Support Surface ◽  
Fungal Cell ◽  
Biofilm Development

ABSTRACT The fungus Cryptococcus neoformans possesses a polysaccharide capsule and can form biofilms on medical devices. We describe the characteristics of C. neoformans biofilm development using a microtiter plate model, microscopic examinations, and a colorimetric 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino) carbonyl]-2H-tetrazolium-hydroxide (XTT) reduction assay to observe the metabolic activity of cryptococci within a biofilm. A strong correlation between XTT and CFU assays was demonstrated. Chemical analysis of the exopolymeric material revealed sugar composition consisting predominantly of xylose, mannose, and glucose, indicating the presence of other polysaccharides in addition to glucurunoxylomannan. Biofilm formation was affected by surface support differences, conditioning films on the surface, characteristics of the medium, and properties of the microbial cell. A specific antibody to the capsular polysaccharide of this fungus was used to stain the extracellular polysaccharide matrix of the fungal biofilms using light and confocal microscopy. Additionally, the susceptibility of C. neoformans biofilms and planktonic cells to environmental stress was investigated using XTT reduction and CFU assays. Biofilms were less susceptible to heat, cold, and UV light exposition than their planktonic counterparts. Our findings demonstrate that fungal biofilm formation is dependent on support surface characteristics and that growth in the biofilm state makes fungal cells less susceptible to potential environmental stresses.

scholarly journals Susceptibility of Cryptococcus neoformans Biofilms to Antifungal Agents In Vitro

2006 ◽  
Vol 50 (3) ◽  
pp. 1021-1033 ◽  
Author(s):  
Luis R. Martinez ◽  
Arturo Casadevall
Keyword(s):  
Confocal Microscopy ◽  
Cryptococcus Neoformans ◽  
Amphotericin B ◽  
Biofilm Formation ◽  
Antifungal Agents ◽  
Capsular Polysaccharide ◽  
Antifungal Drugs ◽  
Enzyme Linked Immunosorbent Assay ◽  
Sequence Of Events ◽  
Biofilm Development

ABSTRACT Microbial biofilms contribute to virulence and resistance to antibiotics by shielding microbial cells from host defenses and antimicrobial drugs, respectively. Cryptococcus neoformans was demonstrated to form biofilms in polystyrene microtiter plates. The numbers of CFU of disaggregated biofilms, 2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-[(phenylamino)carbonyl]-2H-tetrazolium hydroxide reduction, and light and confocal microscopy were used to measure the fungal mass, the metabolic activity, and the appearance of C. neoformans biofilms, respectively. Biofilm development by C. neoformans followed a standard sequence of events: fungal surface attachment, microcolony formation, and matrix production. The susceptibilities of C. neoformans cells of the biofilm and planktonic phenotypes to four antifungal agents were examined. The exposure of C. neoformans cells or preformed cryptococcal biofilms to fluconazole or voriconazole did not result in yeast growth inhibition and did not affect the metabolic activities of the biofilms, respectively. In contrast, both C. neoformans cells and preformed biofilms were susceptible to amphotericin B and caspofungin. However, C. neoformans biofilms were significantly more resistant to amphotericin B and caspofungin than planktonic cells, and their susceptibilities to these drugs were further reduced if cryptococcal cells contained melanin. A spot enzyme-linked immunosorbent assay and light and confocal microscopy were used to investigate how antifungal drugs affected C. neoformans biofilm formation. The mechanism by which amphotericin B and caspofungin interfered with C. neoformans biofilm formation involved capsular polysaccharide release and adherence. Our results suggest that biofilm formation may diminish the efficacies of some antifungal drugs during cryptococcal infection.

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