One or more primers or probes specific for bacteroides fragilis

[Problem] To specifically detect Bacteroides fragilis by avoiding non-specific acquisition of information derived from organisms other than Bacteroides fragilis (e.g., other related bacteria of the genus Bacteroides or hosts such as humans). [Solution] One or more types of primers or probes specific for Bacteroides fragilis capable of detecting one or more types of genes such as 3-carbonyl-5-alpha-steroid 4-dehydrogenase 1 (KO numbering: K12343) and the like; a method for detecting Bacteroides fragilis, which comprises a step for detecting Bacteroides fragilis using the primer or probe; the invention also discloses a detection reagent containing the primer or the probe and used for the bacteroides fragilis. [问题]通过避免非特异性地取得来源于脆弱类杆菌以外的生物(例如，其他的近缘的拟杆菌属细菌、人类等宿主)的信息，而特异性地检测脆弱类杆菌。[解决手段]能够检测3-羰基-5-α-类固醇4-脱氢酶1(KO编号：K12343)等的1种以上的基因的、对脆弱类杆菌特异性的1种以上的引物或探针；包含使用该引物或探针对脆弱类杆菌进行检测的步骤的、脆弱类杆菌的检测方法；以及包含该引物或探针的、脆弱类杆菌的检测试剂。