[Standardization and application on ribotyping library of Clostridioides difficile in China]

Objective: To establish a standard operation procedure (SOP) for ribosome genotyping (ribotyping) on Clostridioides (C.) difficile, supplement and verify ribotyping typing library, so as to improve the comparability of data between different laboratories and to develop surveillance network of C. difficil in China. Methods: Molecular typing of 54 reference strains from the United States and Europe of C. difficile were performed by using the SOP referencing correspondence from abroad and from our laboratory with a BioNumerics 7.6 software to estimate the reference library of types of C. difficile. Identification of 374 clinical and animal isolates of C. difficile from 13 cities in China between 2010 and 2018, to supplement the library information. Kappa test was used to evaluate the consistency. Results: Results of capillary electrophoresis of reference strains appeared clear and stable, which guaranteed the clustering results being fast and accurate. Results from the supplementary typing showed that there were 84 types of isolates, of which 25 RT types were consistent with reference strains from abroad, while 58 RT types were different from referenced types. In the 40 referenced types, 15 RT types were not found in this study. In the consistency evaluation, the Kappa value was 0.891 and (P<0.01), showing the two Molecular typing as consistent and with close resemblance. Conclusions: The result of capillary electrophoresis by applying SOP for ribotyping on C. difficile base on QIAxcel capillary electrophoresis system, appeared clear and stable. The standardized library seemed more easily used for comparability and data sharing between the laboratories.