目的　利用 16S 2 3SrRNA间区的特征建立一种简单、快速的细菌分类方法。方法　以化脓性链球菌 16SrRNA的 3’端和 2 3SrRNA的 5’端的保守区中合成 3对引物 ,PCR扩增 16S 2 3SrDNAISRs ,纯化后直接测序 ,在GenBank上查找对应细菌的ISRs序列。用DNAMAN软件进行系统进化分析。结果　链球菌属为单拷贝 16S 2 3SrRNAISRs片段 ,编码 1个tRNAAla基因。流感嗜血杆菌各生物型出现 2个大小相似的ISRs片段。与GenBank上的资料比较 ,7株链球菌归属 5个种 ,流感嗜血杆菌均为b型。结论　ISRs作为细菌分类新的目标基因具有属、种、型和株特异性与灵敏性 Objective To establish a simple and rapid method of bacterial classification using the features of the 16S 2 3SrRNA intergenic region. Methods Three pairs of primers were synthesized from the conserved regions of 3 ’end of Streptococcus pyogenes 16SrRNA and 5’ end of 23SrRNA. 16S 2 3SrDNAISRs were amplified by PCR and sequenced directly. The corresponding bacterial ISRs were sequenced in GenBank. Phylogenetic analysis using DNAMAN software. Results Streptococcus was a single copy 16S 2 3S rRNAISRs fragment encoding a tRNAAla gene. Haemophilus influenzae biotypes appear in two ISRs fragments of similar size. Compared with the data in GenBank, seven Streptococcus belong to five species, Haemophilus influenzae are b type. Conclusion ISRs as a new target gene of bacterial taxonomy have genus, species, type and plant specificity and sensitivity