USEFULNESS OF RIBOTYPING IN A MOLECULAR EPIDEMIOLOGY STUDY OF SHIGELLOSIS

Ribotyping performed with six restriction endonucleases was used to st udy the molecular epidemiology of shigellosis in Asturias, Spain. The series included Shigella sonnei from 34 sporadic cases, 3 outbreaks an d 3 reference strains, and S. flexneri from 13 sporadic cases and 1 re ference strain. Thr: S. sonnei strains were grouped into 5 ribotypes w ith Sal I, 4 with Hind III and Pvu II, 3; with Bgl II and EcoR I and 2 with Hinc II (Discriminatory Index (DI) between 0.54 and 0.14); the S . flexneri into 5 ribotypes with Sal I, Hinc II and Hind III, and 4 wi th the other enzymes (DI = 0.71-0.63). The combination of results for 2 or more enzymes facilitated an additional discrimination, the highes t values in S. sonnei were for the 6 enzymes (16 types, DI = 0.91) and in S. flexneri for some combinations of 3 or more enzymes (7 types, D I = 0.81). Ribotypes with the 6 enzymes defined 16 clonal lines in S. sonnei and 7 in S. flexneri, which showed a different degree of geneti c heterogeneity, and all the lines of each species falling into a diff erent cluster. No line appeared as clearly endemic in the bowels of As turian people.