Usefulness of spoligotyping in molecular epidemiology of Mycobacterium bovis-related infections in South America

Two hundred twenty-four Mycobacterium bovis isolates, mainly from South Ame rican countries, were typed by spoligotyping, and 41 different spoligotypes were identified. A total of 202 M. bovis isolates (90%) were grouped into 19 different clusters. The largest cluster contained 96 isolates (42.8%) on the basis of the most frequently observed spoligotype, spoligotype 34. Nin eteen M. bovis isolates from humans in Argentina had spoligotypes and polym orphic GC-rich repetitive sequence (PGRS) types that represented the most c ommon types found among isolates from cattle. All five isolates from Urugua y and three of the six isolates from Paraguay had spoligotypes that were al so detected for isolates from Argentina. The spoligotypes of isolates from Brazil, Costa Rica, and Mexico and of some of the isolates Li om Paraguay c ould not be found in Argentina. A total of 154 M. bovis isolates were selec ted in order to compare the discriminative power of spoligotyping and restr iction fragment length polymorphism (RFLP) analysis with direct repeat (DR) and PGRS probes. By spoligotyping, 31 different types were found, while Al uI-digested DR probe-associated RFLP analysis identified 42 types, and RFLP analysis with the PGRS probe also detected 42 types; these mere partly ind ependent of the DR types. By combining the results obtained by spoligotypin g and by RFLP analysis with the DR and PGRS probes, 88 different types were obtained. Although the differentiation of M. bovis by spoligotyping was le ss discriminatory than differentiation by RFLP analysis with the DR and PGR S probes, spoligotyping is easier to perform and its results are easier to interpret. Therefore, for the purpose of typing of M. bovis isolates, spoli gotyping could be performed first and the isolates could be grouped into cl usters and then analyzed by RFLP analysis with the DR and PGRS probes.