Differentiation of Escherichia coli strains using randomly amplified polymorphic DNA analysis

Fifty-nine Escherichia coli strains isolated from 54 unrelated patients over a six-year period, as well as the reference strain of the species, were studied by analysis of randomly amplified polymorphic DNA (RAPD) to assess the usefulness of this genotyping approach in molecular epidemiology. Using a 10-mer oligonucleotide primer, 28 different RAPD fingerprints were distinguished among the 60 strains previously delineated in 36 ribotypes by EcoRI and HindIII digests. The patterns were reproducible and stable after in vitro and in vivo studies. Some strains harbouring an identical ribotype exhibited distinct RAPD fingerprints. Thus, these data illustrate the usefulness of the association of two genetic markers in assessing the relationship between strains. Interestingly, among the RAPD patterns, several bands were present only in the highly virulent carboxylesterase type B2 strains, which are more homogeneous than the carboxylesterase type B1 strains. Because of its simplicity and rapidity, RAPD analysis appears to be a highly valuable tool for studying E. coli molecular epidemiology.