Abstract
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.