Map of aap-aggR loci from strains 042 (producing AAF/II) and 17-2 (producing AAF/I). The aap-aggR locus is highly conserved between the two strains, despite divergence of the fimbrial loci. The aap-aggR intergenic region is 99% identical in the two strains, except for a 50-nucleotide insertion present in the 17-2 sequence. IS, insertion sequence. Values percent indicate nucleotide homology between 042 and 17-2 sequences.