Clinical use comparison of a semiautomated PCR with fluorescent ribotyping for typing of Clostridium difficile

Molecular typing of Clostridium difficile is performed to assess strain relatedness or place strains within an epidemiological context. Different C. difficile ribotyping systems are available. However, a common strain library does not exist. We aimed to compare ribotyping results of 29 clinical C. difficile isolates by two methods: semiautomated PCR-ribotyping and fluorescent PCR-ribotyping. For certain ribotypes (n = 16/29; 55.2 %), the inter-laboratory reproducibility was consistent among multiple samples from individual subjects, while 54.8 % (n = 14/29) were discordant. Additionally, 11/29 ribotypes (38 %) and 12/29 ribotypes (41 %) did not match with known reference strains in the semiautomated PCR-fluorescent ribotyping systems’ libraries, respectively. The identification of 027 ribotype by both systems was consistent for 75 % of the isolates. Discriminatory indices for the semiautomated PCR-ribotyping and fluorescent PCR-ribotyping systems are 0.906 and 0.886, respectively. Although ribotyping provides important epidemiologic insights, the lack of a common strain library makes interpretation of results using different ribotyping protocols difficult.