To evaluate the usefulness of multiple-locus variable-number tandem-repeat analysis (MLVA) as a tool for the epidemiological analysis of bovine Salmonellosis, isolates of Salmonella enterica serotype Typhimurium and serotype 4,5,12:i:- (544 and 18, respectively) from cattle in Hokkaido, Japan, from between 1977 and 2009, were characterised by MLVA. MLVA identified 184 profiles, compared with 121 profiles identified by pulsed-field gel electrophoresis (PFGE). Cluster analysis of the MLVA profiles identified 3 major clusters (A–C) and 3 minor clusters (D–F). Cluster A was associated with PFGE cluster I, which included isolates of definitive phage type 104 (DT104), while cluster C was associated with PFGE cluster VII, which has been disseminating among cattle since 2002. Overall, the discriminatory power of MLVA was higher than that of PFGE. However, this was dependent on PFGE clusters, because PFGE was more discriminating between isolates within PFGE clusters IV and VI than MLVA. The combination of data from PFGE and MLVA allowed for improved subtype discrimination and it was possible to identify the recently disseminated clones. Hence, MLVA can be used to complement PFGE, thus effectively accelerating molecular epidemiologic investigations of Salmonella.
(Dairy Hygiene Research Division)
Kurosawa A. et al. (2012) Vet. Microbiol. 160(1-2):264-268