ANALYSIS OF ERYSIPELOTHRIX-RHUSIOPATHIAE AND ERYSIPELOTHRIX TONSILLARUM BY MULTILOCUS ENZYME ELECTROPHORESIS

The genetic diversity of 74 Australian field isolates of Erysipelothri x rhusiopathiae and 22 reference strains for serovars of E. rhusiopath iae or Erysipelothrix tonsillarum was examined by multilocus enzyme el ectrophoresis. Four serovar reference strains of E. tonsillarum (strai ns KS 20 A, Wittling, Lengyel-P, and Bane 107 for serovars 25, 3, 10, and 22, respectively) were genetically distinct from E. rhusiopathiae. However, the E. tonsillarum reference strain for serovar 14 (Iszap-4) and the reference strain for serovar 13 (Pecs-56), which has been sai d to represent a new genomic species, were found to cluster with typic al isolates and reference strains of E. rhusiopathiae. Our reference s train for serovar 7 (Rotzunge) was also genetically typical of E. rhus iopathiae, thus indicating that these serotype reactivities cannot be relied upon as a means of identifying isolates as E. tonsillarum. Aust ralian field isolates off. rhusiopathiae were genetically diverse. Tho se recovered from sheep or birds were more diverse than those isolated from pigs, and isolates of serovar 1 were more diverse than those of serovar 2. The diversity found among isolates of the same serovar and the presence of isolates of different serovars in the same electrophor etic types (ETs) indicated that serotyping of E. rhusiopathiae was unr eliable for use as an epidemiological tool. Some ETs contained isolate s recovered from different animal species. ET 41 contained 32.2% of th e field isolates and two reference strains, indicating that this clone of E. rhusiopathiae is both widespread and commonly associated with d isease in various species of animals.