白假丝酵母菌不同菌株荚膜厚度对动物致病性影响的对比

背景：作者前期实验发现多株白假丝酵母菌菌株具有荚膜结构，荚膜与该菌的毒力是否有关？ 目的：观察白假丝酵母菌标准菌株与临床分离菌株对动物的致病差异，验证荚膜是否是该菌的毒力因子，并分析不同菌株对动物致病性与荚膜厚度的关系。 设计：随机对照动物实验。 单位：赣南医学院病原生物学教研室。 材料：实验于2005—05／06在赣南医学院科研中心完成。选用BALB／c小鼠120只，健康成年家兔72只。白假丝酵母菌：中央标准菌株（菌号：CCCMC1a），国际标准菌株（菌号：ATCC 14053），分离培养的4株临床菌株暂行自编菌号为C1—1，C1—2，C1—3，C1-4。 方法：将实验动物按随机数字表法分为6组，即CCCMC1a，ATCC14053，C1—1，C1-2，C1—3，C1-4组，每组小鼠20只，家兔12只。将实验菌种沙保氏琼脂36h培养物用生理盐水配成菌悬液，家兔耳缘静脉注射，1．5mL/只；BALB/c小鼠腹腔注射，0．5mL/只。注射后6h开始观察动物的反应，记录动物发病时间、死亡时间及死亡率。 主要观察指标：①家兔肾组织印片及小鼠腹腔液涂片观察。②Hiss荚膜染色镜检，显微测微计测量荚膜层厚度（n=40），比较各菌株荚膜层厚度均值。 结果：①与C1-1，C1-3，CCCMC1a，ATCC 14053相比，C1—2和C1—4对动物具有很强的致病性。②标准菌株和临床分离菌株在家兔及小白鼠体内均可形成荚膜，荚膜层的厚度可因菌株和动物种属不同而存在差异（P〈0．05—0．01）。兔肾感染灶的菌细胞较小鼠腹腔内菌细胞的荚膜宽厚；C1—1，C1-2，C1—3，C1-4组兔肾感染灶的菌细胞及鼠腹腔内菌细胞的荚膜分别比同种属CCCMC1a，ATCC 14053组宽厚，其中C1-2，C1—4组兔肾感染灶的菌细胞及鼠腹腔内菌细胞的荚膜最为宽厚。结论：白假丝酵母菌C1-2和C1-4菌株对动物具有很强的致病性，它们的荚膜比其他菌株更宽厚。初步验证了荚膜可能是白假丝酵母菌的毒力因子，荚膜的宽厚与动物致病性有着密切的联系。

Comparison of animal pathogenicity of Candida albicans at different strain capsule thickness

BACKGROUND: Previous studies have demonstrated that Candida albicans possesses capsule structure. Whether capsule structure is associated with the virulence of Candida albicans?OBJECTIVE: This study investigated the pathogenic difference between the standard strains of Candida albicans and the clinically isolated strains, verified whether capsule was the virulence factor of the Candida albicans, and analyzed the association between the animal pathogenicity of different strains and capsule thickness.DESIGN: A randomized controlled animal experiment.SETTING: Department of Pathogenic Biology, Gannan Medical College.MATERIALS: This study was performed at the Scientific Research Center, Gannan Medical College between May and June 2005. A total of 120 BALB/c mice and 72 healthy adult rabbits were included. Candida albicans strains (CCCMC1a and ATCC 14053) were used. The isolated and cultured 4 strains were numbered as C1-1, C1-2, C1-3,and C1-4.METHODS: All animals were randomly divided into 6 groups with 20 mice and 12 rabbits in each group, namely,CCCMC1a, ATCC 14053, C1-1, C1-2, C1-3, and C1-4 groups. Strains smeared in sabouraud ager medium for 36 hours were diluted into the bacterial solution with physiological saline. This solution was intravenously injected into rabbit ear edge, 1.5 mL per rabbit, and intraperitoneally injected into BALB/c mice, 0.5 mL per mouse. Six hours after administration, animal response was observed, and attack time, death time, and mortality were recorded.MAIN OUTCOME MEASURES: Rabbit nephridial tissue printing slices and mouse peritoneal fluid smears were made for Hiss capsule staining microscopy. The capsule thickness of 40 randomly selected yeast cells in each strain was measured using a microscope-micrometer, and the mean capsule thickness of each strain was compared.RESULTS: Compared with C1-1, C1-3, CCCMC1a, and ATCC 14053, C1-2 and C1-4 possessed stronger animal pathogenicity. The standard strains and clinically isolated strains could form capsule in the rabbit and mouse bodies. Capsule thickness differed due to different strains and animal genera (P < 0.05-0.01). The bacterial capsule thickness was greater in the rabbit renal infection focus than in the mouse abdominal cavity. The bacterial capsule thickness of rabbit renal infection focus and mouse abdominal cavity in the C1-1, C1-2, C1-3, and C1-4 groups was greater than that of the same genus in the CCCMC1a and ATCC 14053 groups. The bacterial capsule thickness of rabbit renal infection focus and mouse abdominal cavity was the greatest in the C1-2 and C1-4 groups.CONCLUSION: Candida atbicans C1-2 and C1-4 strains have strong animal pathogenicity. C1-2 and C1-4 strains possess greater bacterial thickness than other strains. It has been primarily confirmed that capsule is possibly a virulence factor of Candida albicans, and capsule thickness is closely associated with animal pathogenicity.