Efficient subtyping of Yersinia enterocolitica bioserotype 4/O : 3 with pulsed-field gel electrophoresis

The purpose of this study was to evaluate the efficiency of pulsed-field ge l electrophoresis (PFGE) for differentiation of isolates of Yersinia entero colitica bioserotype 4/O:3 recovered from pig tongues at retail level in th e Helsinki area during October and November of 1996. NotI generated 15 diff erent PFGE patterns for 128 isolates. The discriminatory index did not exce ed 74% due to the presence of two predominant PFGE-types, NA1 (58/128) and NB1 (25/128). After preliminary investigations with 35 enzymes, ApaI, XbaI, XhoI and SpeI were chosen for further characterization of the isolates. Th e discriminatory index increased from 74% to 93% and the number of differen t genotypes from 15 to 30 when isolates with the same PFGE pattern with Not I were further characterized with ApaI and XhoI, indicating that PFGE can b e an efficient technique for characterization of bioserotype 4/O:3.