FIG. 3.

MPCR analysis of intermediate strains. Single colonies of intermediate strains were directly incubated in the PCR mixture, lysed by the initial denaturation step, and analyzed by MPCR as described in Materials and Methods. All intermediate strains, i.e., 2771/97 (uidA positive, stx₂ positive, estIa positive), 04-3908 (uidA positive, stx₂ positive, estIa positive, astA positive), 265-1 (uidA positive, bfpB positive), and 4932-53 (uidA positive, bfpB positive), exhibit unusual genotypes. The negative control was tested with the MPCR set of primer pairs but lacked template DNA. Lanes M contained molecular size markers.