Abstract:

Objective To study the in vitro expression of virulence factors and the drug resistance of oral Candida albicans,including the secretion of hydrolytic enzymes,biofilm formation and mycelium phase production,and to investigate the correlations. Methods The activities of secreted aspartyl proteinase（SAP）,phospholipase（PL） and lipase（Lip） of Candida albicans were determined by bovine serum albumin agar,egg yolk agar and tributyrate agar,respectively. The formation of biofilm was determined by crystal violet staining assay,and the expression of hyphal wall protein 1（HWP1） gene was determined by real-time fluorescence polymerase chain reaction（PCR）. Antibiotic susceptibility test was performed. Results The 80% isolates produced a high level of SAP,98% isolates displayed a high level of PL,78% isolates produced a medium level of Lip,and none displayed a high level of Lip. All isolates were able to form biofilm,and the ability of biofilm formation of 30 isolates（60%） was strong. There was a positive correlation between the in vitro expressions of SAP and PL（P<0.05）. No relationship was found in the other virulence factors,while there was no statistical significance in the level of virulence factors in vitro and HWP1 expression between drug-resistant and drug-sensitive isolates. Conclusions Most of isolates display high levels of SAP and PL and medium levels of Lip,which produce biofilm strongly. There is a positive correlation between the in vitro expressions of SAP and PL. The virulence of oral Candida albicans has no correlation with drug resistance.

Key words: Candida albicans, Virulence factor, Hydrolytic enzyme, Biofilm, Hyphal wall protein 1 gene