Molecular and Phenotypic Methods for Identifying Mycobac

对快速生长的分枝杆菌和诺卡菌的一部分基因组进行聚合酶链反应（PCR）扩增，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有用的技术。与基于生化测试的常规鉴定需要一个月或更长时间相比，这些生物的物种鉴定可以在生物分离后的几天内获得。此外，与生物化学测试相比，这些分子程序可以更准确地区分物种和亚种。我们对诺卡菌基因组的两个不同区域（16S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，迄今为止尚未被认识的诺卡菌物种的存在；进一步鉴定这些生物的工作正在进行中。此外，我们还发现了几个临床分离株，属于诺卡菌的种类，据我们所知，这些菌株以前没有在西半球的患者中引起疾病的报告。一份描述我们方法中RFLP组成部分的手稿已经发表。DNA-DNA杂交目前正被用来更精确地确定我们的分离物中哪些属于不寻常的但已经被描述过的物种，哪些分离物可能属于迄今未被描述过的物种。基于表型和其他分子生物学特征的这些分离物的特征也正在进行中。事实上，一些不寻常的诺卡菌可致病性慢性肉芽肿病的患者也已注意到另一篇手稿。

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.