MPCR analysis of reference strains. Twelve primer pairs were designed for the specific detection of the seven major categories of intestinal pathogenic E. coli. All of the primer pairs yield specific gene products indicating the appropriate pathotypes and generate no unspecific products. The amplicons can be differentiated by agarose gel electrophoresis (2%). Lanes M contained molecular size markers. The other lanes contained EPEC strain E2348/69 (uidA positive, LEE positive, bfp positive), ATEC strain 9812 (uidA positive, LEE positive), STEC strain EDL933 (uidA positive, LEE positive, stx1 positive, stx2 positive), STEC strain 04-3175 (uidA positive, stx1 positive, stx2 positive), ETEC strain 164/82 (uidA positive, elt positive, estIa positive), ETEC strain 117/86 (uidA positive, estIb positive), EIEC strain 99-10282 (uidA positive, invE positive), EAEC strain 02-1850 (uidA positive, astA positive, aggR positive, pic positive), E. coli C600 (uidA positive), and a negative control lacking template DNA.