title: Enhancement of secretory aspartyl protease production in biofilms of Candida albicans exposed to sub-inhibitory concentrations of fluconazole.
abstract: The production of Secretory Aspartyl Proteases (Sap) is an important virulence factor of Candida albicans. Many studies have shown that a challenge with sub-inhibitory concentrations of antifungals lead species of Candida to the secretion of higher concentrations of Sap. Nevertheless, published studies only reported the secretion of such enzymes by cells growing in planktonic phase, with few mention of biofilms. The present study evaluated the alterations in the secretion of Sap by C. albicans grown in biofilms and exposed to sub-inhibitory concentrations of fluconazole. The MICs for fluconazole of seven clinical strains were determined for planktonic cells. Biofilm and planktonic cells were grown in the presence of ½ MIC, ¼ MIC, and no medication (control). The relative metabolic activity, indirectly related to cell loads, were estimated by the absorbance of reduced XTT and the Sap activity was evaluated by bovine albumin test. It was observed that 72 h-old biofilms under the influence of ½ MIC had fewer cells than ¼ MIC and control. The production of Sap was inversely proportional to the cell content, with higher secretion in ½ MIC, followed by ¼ MIC and control. Biofilms of C. albicans challenged by sub-MICs of fluconazole tend to secrete higher quantities of Sap.
authors.affiliation: The Pontifical Catholic University of Paraná, Laboratory of Stomatology, Curitiba, PR, Brazil.
authors.forename: Alinne Ulbrich
authors.initials: AU
authors.lastname: Mores
authors.forename: Roberta Djavana
authors.initials: RD
authors.lastname: Souza
authors.forename: Laura
authors.initials: L
authors.lastname: Cavalca
authors.forename: Alessandra
authors.initials: A
authors.lastname: de Paula e Carvalho
authors.forename: Lauren Christine
authors.initials: LC
authors.lastname: Gursky
authors.forename: Rosimeire Takaki
authors.initials: RT
authors.lastname: Rosa
authors.forename: Lakshman Perera
authors.initials: LP
authors.lastname: Samaranayake
authors.forename: Edvaldo Antonio Ribeiro
authors.initials: EA
authors.lastname: Rosa
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology*; D057055:Aspartic Acid Proteases / Q000378:metabolism*; D018441:Biofilms / Q000187:drug effects*; D002176:Candida albicans / Q000187:drug effects* / Q000201:enzymology* / Q000378:metabolism; D015725:Fluconazole / Q000494:pharmacology*; D006801:Humans; D008826:Microbial Sensitivity Tests; D013053:Spectrophotometry; D013778:Tetrazolium Salts / Q000378:metabolism; D037521:Virulence Factors / Q000378:metabolism*
chemical_list: D000935:Antifungal Agents; D013778:Tetrazolium Salts; D037521:Virulence Factors; C059087:2,3-bis(2-methoxy-4-nitro-5-sulfophenyl)-5-((phenylamino)carbonyl)-2H-tetrazolium hydroxide; D015725:Fluconazole; D057055:Aspartic Acid Proteases