鸡毒支原体敏感株与耐药株超微结构的比较

对临床分离和实验室药物压力下筛选的鸡毒支原体耐药株与敏感株进行超微结构的观察和比较.结果显示鸡毒支原体敏感株呈多形性,柔软且有较大的变形性,可清晰观察到细胞膜分为外、中、内三层膜,并可观察到裂殖繁殖方式;有的支原体在繁殖时先在极端产生泡状突起,形成不均等分裂.在恩诺沙星药物压力下敏感株产生耐药性后其外膜显著增厚,导致支原体的多形性减弱或消失,呈现出较为一致的圆形;细胞膜内层周围存在排列整齐、结构紧密、类似微管样的结构,胞内电子密度明显升高.临床分离的耐药株超微结构观察结果与实验室条件下筛选的耐药株一致:凡是超微结构发生变化的,均存在耐药表型,而且高水平耐药株的超微结构变化最为突出.研究结果表明耐药性的产生可导致鸡毒支原体超微结构明显的改变,并可能引起抗原性变异.

Ultrastructural comparison on sensitive and resistance strains of Mycoplasma gallisepticum

The ultrastructures of sensitive and resistant strains of Mycoplasma gallisepticum (Mg) were observed with transmission electron microscopy.The outer,middle and inner three layer membranes of both sensitive strains and resistant strains could be clearly observed.Sensitive strains were floppy and more variable in their shapes,occurring simultaneously in two or three replicative phases,such as schizogony,while resistant strains selected by fluoroquinolones were less variable and more uniform with rounded shapes,having markedly thicker membranes and higher electron density than that of the sensitive strains,showing microtubular like structure under the inner layer and bubble like material over the outer layer.This phenomenon suggested that some proteins might be overexpressed.Resistant strains isolated from the field exhibited the same pattern under the transmission electron microscope.So the resistance of Mg to Fluoroquinolones might be closely related to changes in ultrastructures,and responsible to the variation of the antigenicity of Mg.