Restriction fragment length polymorphism of PCR amplifiedpapE gene products is correlated with complete serotype among uropathogenicEscherichia coliisolates

Using whole bacteria, rather than extracted, purified DNA samples, we amplified thepapE gene sequences from 63Escherichia coliisolates belonging to O serogroups O1, O2 and O6. These isolates were from collections separated temporally as well as geographically: from four cities in the US and one in Sweden. PCR amplifiedpapE products were digested with restriction endonucleases and the relative sizes of the fragments compared for each strain. For 41 of the strains, we found a correlation between thepapE restriction fragment length polymorphism (RFLP) and the complete serotype. Furthermore, we were able to detect the presence of duplicate copies of the gene in 14 of the isolates; these 14 isolates were among the 22 that did not exhibit a correlation between the RFLP of their amplifiedpapE sequences and their complete serotype. We conclude that RFLP analysis of PCR products is a rapid and relatively simple method for examining the DNA ofE. colicontaining thepapgene sequence.