Provost F, Blanc M V, Beaman B L, Boiron P
Institut Pasteur, Unit of Mycology, Paris, France.
J Med Microbiol. 1996 Nov;45(5):344-8. doi: 10.1099/00222615-45-5-344.
The purpose of the present study was to determine the relative distribution of plasmids in 87 clinical isolates of Nocardia, belonging to the five major pathogenic species. A correlation between plasmid content and the site of infection within the host, resistance to antibiotics and enzymic profiles was also investigated. The plasmid extraction procedure of Kado and Liu was used. Electrophoretic analysis revealed one-to-four plasmid bands, ranging in size from <8 to >50 kb, in 27 strains (31%). Based on the number of isolates tested, the incidence of plasmid-bearing strains was significantly higher among N. farcinica than N. asteroides strains. Within N. farcinica, the incidence of plasmids was higher among strains isolated in the Paris area than in strains isolated elsewhere, such as in the French provinces or outside France. A statistically significant correlation was demonstrated between the cutaneous localisation of infections and the incidence of plasmid-bearing strains. The presence of plasmids in nocardiae could not be associated with specific phenotypic traits such as resistance to antibiotics or enzymic activity. The fact that the majority of Nocardia clinical isolates (60 of 87) did not contain plasmids suggests that plasmids are not involved directly in virulence and that there is no selective pressure for plasmid acquisition.
本研究的目的是确定属于五个主要致病菌种的87株诺卡菌临床分离株中质粒的相对分布情况。同时还研究了质粒含量与宿主内感染部位、抗生素耐药性及酶谱之间的相关性。采用了Kado和Liu的质粒提取方法。电泳分析显示，27株（31%）菌株中有1至4条条带，大小从小于8kb到大于50kb不等。根据检测的分离株数量，在豚鼠诺卡菌中携带质粒的菌株发生率显著高于星形诺卡菌。在豚鼠诺卡菌中，巴黎地区分离的菌株中质粒发生率高于其他地方分离的菌株，如法国其他省份或法国以外地区。感染的皮肤定位与携带质粒菌株的发生率之间存在统计学上的显著相关性。诺卡菌中质粒的存在与诸如抗生素耐药性或酶活性等特定表型特征无关。87株诺卡菌临床分离株中的大多数（60株）不含质粒，这一事实表明质粒不直接参与毒力，并且获取质粒不存在选择压力。
