Molecular and Phenotypic Methods for Identifying Mycobac

聚合酶链反应（PCR）扩增快速生长的分枝杆菌和诺卡氏菌基因组的一部分，然后对扩增产物进行限制性片段长度多态性（RFLP）分析，已被证明是诊断实验室中的一种有用技术。与基于生化检测的常规鉴定所需的一个月或更长时间相比，在微生物分离后的几天内就可以将这些微生物鉴定到物种水平。此外，这些分子程序允许更准确的物种和亚种之间的区别比可能与生化检测。我们对诺卡氏菌基因组的两个不同区域（16 S核糖体RNA基因的一部分和热休克蛋白基因的一部分）的研究表明存在迄今未被识别的诺卡氏菌属物种;正在进行进一步表征这些生物体的工作。此外，我们还发现了几个属于诺卡氏菌属的临床分离株，据我们所知，这些分离株以前没有在西半球的患者中引起疾病的报道。描述我们方法中RFLP部分的手稿已经出版。DNA-DNA杂交目前正被用来更精确地确定哪些我们的分离株属于不寻常的，但已经描述的物种，哪些分离株可能属于迄今未描述的物种。基于表型和其他分子生物学特征的这些分离株的表征也在进行中。事实上，一些不寻常的诺卡氏菌属物种可以在慢性肉芽肿性疾病患者的致病性也已注意到在另一份手稿。

Polymerase chain reaction (PCR) amplification of a portion of the genome of both rapidly growing mycobacteria and nocardiae, followed by restriction fragment length polymorphism (RFLP) analysis of the amplification products, has proven to be a useful technique in the diagnostic laboratory. Identification of these organisms to the species level can be obtained within a few days of organism isolation, as compared with the month or more required for conventional identification based on biochemical testing. In addition, these molecular procedures allow more accurate discrimination among species and subspecies than is possible with biochemical testing. Our work with two different areas of the Nocardia genome (a portion of the gene for 16S ribosomal RNA and a portion of the gene for the heat-shock protein) has suggested the existence of hitherto unrecognized Nocardia species; work is ongoing to characterize these organisms further. In addition, we have found several clinical isolates belonging to species of Nocardia that have not, so far as we know, been previously reported to cause disease in patients in the western hemisphere. A manuscript describing the RFLP component of our methodology has been published. DNA-DNA hybridization is currently being utilized to define more precisely which of our isolates belong to unusual but already-described species, and which isolates might belong to hitherto undescribed species. A characterization of these isolates based on phenotypic and other molecular biologic features is also underway. The fact that some unusual Nocardia species can be pathogenic in patients with chronic granulomatous disease has also been noted in another manuscript.