Relationship Between Phospholipase And Its Virulence Attributes And Drug Resistance And RAPD Typing Of C.albicans

Objiective Putative virulence factors of Candida albicans include:cell wall adhesins, secretion of hydrolytic enzymes(secreted aspartyl proteinase, phospholipase) and phenotypic switching. The phospholipases in general catalyse the hydrolysis of phospholipids, which are major components of all cell membranes, and then C. albicans entry from the damaged cell. However, it is not clear that association between phospholipase production and virulence factors of C. albicans. Hence the objectives of the current study were to screen isolates of C. albicans for phospholipase activity, then divided into the phospholipase-highly activity group and phospholipase-low activity group, and determine the association, if any, between phospholipase activity and other virulence attributes of C. albicans(haemolysin production, cell surface hydrophobicity, adhesion to buccal epithelial cells), furth to investigate the correlation of phospholipase activity and drug resistance and the genotypic of C.albicans. Provide experimental basis on in-depth understanding the role of phospholipase in pathogenicity and in drug resistance of C. albicans. Provide new prospects for the development of antifungal agents and C. albicans disease diagnosis and treatment.Method A semi-quantitative way (egg yolk agar) was used to evaluate phospholipase activities of 80 C.albicans strains, with PZvalue that phospholipase activity. Based on the PZ value,10 phospholipase-highly activity (group A) strains and 10 phospholipase-low activity (groupB) strains were obtained from the clinical isolates. Haemolysin production, cell surface hydrophobicity, adhesion to buccal epithelial cells were in turn characterized of the two groups,differences in drug resistance of the two groups was compared by the drug susceptibility test, total DNA was extracted from C. albicans isolates and RAPD was used to analysis the genotypic of these two groups.Result In the current study, of the 80 isolates of S. albicans tested,78 were phospholipase-positive according to the plate assay.97.5% of S.albicans strains tested produced phospholipase, the range of PZ values observed was 0.566～1.000. The PZ mean for the groups of isolates were 0.639±0.043 and 0.847±0.079, respectively (P<0.05).The haemolysin production and the cell surface hydrophobicity between the two groups were no significantly different (r=0.122,P>0.05),(r=0.072, P>0.05, but the adhesion to buccal epithelial cells between the two groups was significantly different (P<0.05), and a positive correlation was demonstrated between phospholipase activity and adhesion to buccal epithelial cells (r=0.773,P<0.01). Resistance on the seven kinds of antifungal drugs of the two groups is obviously different. Resistance rate of the strains of groupA to econazole is 70%, moderately susceptible or resistance appeared on miconazole,fluconazole,itraconazole. Resistance rate of the strains of groupB to Econazole is 10%, sensitive appeared on the rest six drugs. RAPD results showed that two phospholipase-negative strains as a distinct genotype.The number and location of the major bands of the remaining strains were smaller, show a high brightness band in the 1300 bp and three bands in the>1500 bp, the similarity coefficient varied from 0.500 to 1.000, strains of gene polymorphism did not show significant differences, so there were homology between them.Conclusion Most clinical isolates of C.albicans can produce phospholipase, phosphlipase is one of the most important virulence attributes of C.albicans.There are some correlation betwent phospholipase activity and adhesion to epithelial cells of C.albicans, but there no such association emerged for haemolysin production and cell surface hydrophobicity. So phospholipase activity can not reflect other virulence attributes of C.albicans. RAPD typing can not reflect the phospholipase activities of C.albicans directly. Note that this technique is comprehensive reflection of hemolytic activity, cell surface hydrophobicity, adhesion and drug resistance and other characteristics, more than simply reflect phospholipase characteristics.