The Influence Of Different Cultural Conditions On Germ Tube Formation In Candida Albicans

Objective:1.To evaluate the influence of different cultural conditions (temperature,time,pH,alternative oxidase and dexamethasone)to the formation of germ tube of Candida albicans and detect the germ tube quantitatively.2.To study the role of source location in the pathogenicity Candida albicans.3.To compare with the incidence of germ tube of fluconazole susceptible strains,fluconazole dose-department susceptible and resistant strains in the same condition。Method:1.Using fetal calf serum(FCS),inactivated human serum,RPMI1640 medium and DMEM medium,to induce the germination of Candida albicans under different conditions(temperature,time,pH and concentration of inoculum);and calculate the incidence of germ tube by the method of crystal violet staining.2. Fluconazole-susceptible strains,fluconazole dose-department susceptible and resistant strains were selected from the strains of Candida albicans according to the NCCLS M-27 microdilution method.Furthermore,calculate and compare the incidence of germ tube.3.GMP(final concentration 2mg/ml)is added to Candida albicans suspended in RPMI1640 medium(1×10~5 cell/ml,pH4),and the cells were incubated at 37℃for 2h.SHAM(final concentration 1mg/ml)is added to Candida albicans suspended in RPMI1640 medium(1×10~5cell/ml,pH7),and the cells were incubated at 37℃for 2h.4.The strains of Candida albicans were cultured on RPMI1640,which include different concentration of dexamethasone.Results:1.Under the same condition,the incidence of germnation in FCS is significantly higher than in RPMI1640 medium and DMEM medium(P＜0.05),and there is no significant difference between the later two(P＞0.05).The highest incidence of germnation occurred in concentration of inoculum of Candida albicans of 5×10~6 cfu/ml with the FCS,under the condition of pH7.0,37℃and 2 hours of incubation;and the incidence of germnation is on a decline when the concentration of Candida albicans is over 5×10~6 cfu/ml.2.The incidence of germnation from different parts of the source of Candida albicans strains had a significant difference(P＜0.001).The incidence of germnation was higher in the strains from systemic infection than that from cutaneous mucosal infection,there is no significant difference between the later two(P＞0.05).3.At the same time cultivation,the incidence of germnation was signficantly lower for fluconazole susceptible than that for fluconazole dose-dependent suscepible and resistant strains in RPMI1640 medium at 370℃.4.The addition of GMP,induced the hyphal growth pH 4.Although Candida albicans grew in hypal form in pH 7,SHAM enhanced the yeast proliferation at this pH.5.When the concentration of dexamethasone are 0.05 mg/ml,0.1 mg/ml and 0.2 mg/ml,there is no significant difference in the incidence of germnation between the dexamethasone-absent group and the dexamethasone-present group.However,there is there is significant difference in the incidence of germnation when the concentrations of dexamethasone are 0.4 mg/ml,0.8 mg/ml and 1.0 mg/ml.Conclusion:1.The incidence of germnation of Candida albicans can be increased by optimizing the culture conditions,and crystal violet staining can quantitatively detect the incidence of germination accurately.2.Different parts of the source of Candida albicans strains have probably differernt virluence and pathogenicity. 3.The incidence of germnation of Candida albicans relate to the level of sensitivity of the fluconazole.4.Alternative oxidase can influence on the dimorphism of Candida albicans.5.Hypo-concentrations of dexamethasone(0.05 mg/ml,0.1 mg/ml and 0.2 mg/ml)have no significant difference in the growth Candida albicans between the dexamethasone-absent group and the dexamethasone-present group.A concentrations of dexamethasone(0.4 mg/ml,0.8 mg/ml and 1.0 mg/ml)indicate a significant difference between the two.