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目的评价不同条件、不同来源和不同血清型的新生隐球菌分泌磷脂酶的情况;观察胞外磷脂酶对菌株毒力的影响。方法分别在30℃和37℃下用蛋黄平板法培养不同来源的40株新生隐球菌,计算沉淀圈比值(PZ值),比较其磷脂酶活力的不同;建立小鼠感染模型,用小鼠的平均生存期及脑组织菌落形成单位(cfu)比较分泌磷脂酶和不分泌磷脂酶菌株毒力的变化。结果39株菌的菌落周围产生明显白色沉淀圈,PZ值在30℃和37℃培养条件下分别为0.529±0.121和0.523±0.143;血清型A、B及AD和D型的PZ值分别为0.541±0.116、0.518±0.036和0.472±0.051;不同温度间和不同血清型组间差异均无显著性(P>0.05);临床株和环境株PZ值分别为0.501±0.049和0.565±0.131,差异有显著性(P<0.05)。感染分泌磷脂酶菌株和不分泌磷脂酶菌株两组小鼠脑组织的cfu分别为518.67±203.86和226.47±196.13,两组小鼠的平均生存期分别为18.90d和26.39d,差异有显著性(P<0.01)。结论温度对新生隐球菌磷脂酶活力没有影响;其中临床分离株比环境分离株磷脂酶活力强;不同血清型菌株的磷脂酶活力无差别;分泌磷脂酶的菌株毒力比不分泌磷脂酶菌株的毒力强。
Objective To evaluate the secretion of phospholipase by Cryptococcus neoformans in different conditions, different sources and different serotypes and observe the effect of extracellular phospholipase on the virulence of strains. Methods 40 strains of Cryptococcus neoformans from different sources were cultured by egg yolk plate method at 30 ℃ and 37 ℃, respectively. The ratio of sedimentation circle (PZ) was calculated and the phospholipase activity was compared. The mouse model of infection was established, Mean survival time and brain cfu colony forming units (cfu) compared the secretion of phospholipase and not secreting phospholipase strains virulence changes. Results The 39 strains showed obvious white precipitation around the colony, PZ values were 0.529 ± 0.121 and 0.523 ± 0.143 respectively at 30 ℃ and 37 ℃. The PZ values of serotypes A, B, AD and D were 0.541 ± 0.116,0.518 ± 0.036 and 0.472 ± 0.051 respectively. There was no significant difference between different temperature groups and different serogroups (P> 0.05). The PZ values of clinical strains and environmental strains were 0.501 ± 0.049 and 0.565 ± 0.131, respectively Significance (P <0.05). The cfu of brain tissue in mice infected with secreted phospholipase and non-secreted phospholipase were 518.67 ± 203.86 and 226.47 ± 196.13 respectively, the average survival time was 18.90d and 26.39d in both groups, with significant difference ( P <0.01). Conclusion The temperature had no effect on the phospholipase activity of Cryptococcus neoformans. The clinical isolates had stronger phospholipase activity than the environmental isolates, no difference in phospholipase activity among different serotype strains, Toxic.