Comparison of automated ribotyping and pulsed-field gel electrophoresis for subtyping of Vibrio cholerae

To compare the discriminatory power of an automated ribotyping method for Vibrio cholerae subtyping with the pulsed-field gel electrophoresis (PFGE), to evaluate the possibility of automated ribotyping in use of outbreak investigations and surveillance of cholera. Eight-one epidemiologically unrelated isolates of V. cholerae, and 19 isolates from seven cholera outbreaks were used as the panels. When comparing the two methods using the epidemiologically unrelated isolates, automated ribotyping using PvuII distinguished 38 different ribotypes with a D-value of 0.8956. When combined with serotyping, the D-value is 0.9466. However, PFGE with NotI and SfiI digestions had higher D-values of 0.9951 and 0.9948, respectively. PFGE could cluster the isolates from each outbreak into the same pattern, and distinguish different patterns from different outbreaks, whereas automated ribotyping had lower discriminatory ability. The automated ribotyping has lower discriminatory ability compared to PFGE, and is limited to application in V. cholerae subtyping and outbreak investigation. The study evaluated the limitation in subtyping of automated ribotyping for V. cholerae, and raise the question of improvement for the automated ribotyping in subtyping.