Validation of an enhanced method of bacterial ribotyping for improved efficiency and identification of stressed isolates

Historically, it has been virtually impossible to get sameday microbiological identification results. The use of such systems requires compliance with strict conditions for incubation, media types, number of transfers, and ancillary testing before submission of the sample for analysis. The DuPont Qualicon RiboPrinter microbial characterization system is an automated ribotyping system for rapid bacterial identification and characterization to the strain level. The instrument performs a Southern blot analysis using the DNA from a bacterial sample. The image from the blot is captured with a charge-coupled device camera and the data is converted into a RiboPrint pattern, which is compared with known RiboPrint patterns in the database. If the pattern from the sample matches a known pattern from the database with a minimum similarity rating of 85%, the sample is identified with a genus and species. A three-part study was undertaken to validate the existing RiboPrinter microbial characterization system; to expand and validate the method to include frozen storage of heat-treated samples for one month before initiating identification to allow for more efficient and flexible isolate processing; and to expand the manufacturer's method to use cultures grown as long as 72 h for the recovery of slow-growing and stressed organisms. Results are presented in this article.