Random amplification of polymorphic DNA reveals serotype-specific clonal clusters among enterotoxigenic Escherichia coli strains isolated from humans

Abstract

The genetic diversity of 47 enterotoxigenic Escherichia coli (ETEC) strains of serotypes O6:H16, O27:H7, O29:H21, O128ac:H12, and O153:H45, previously isolated from diarrheic patients in Brazil over a period of 15 years, was investigated by random amplification of polymorphic DNA (RAPD). Informative band arrays were obtained with three 10-mer primers with G؉C contents of 50, 60, and 70%. Based on the combination of the band profiles generated by the three primers 22 RAPD types were detected, and 5 major clonal clusters, each one with at least 80% identical bands, were established. The clonal clusters corresponded to strains having the same serotype which, in most cases, also had the same virulence factors (colonization factors and toxin types) and outer membrane protein and lipopolysaccharide sodium dodecyl sulfate-polyacrylamide gel electrophoresis profiles. The results suggested a correlation between phenotypic properties and genetic relatedness of ETEC isolates of human origin and indicated that a reduced number of clonally related strains are found in areas of ETEC endemicity in Brazil. Moreover, the RAPD technique revealed intraserotype-specific variations, undetectable by the combination of several phenotypic typing methods, among the ETEC strains analyzed. These results show that RAPD typing represents a useful tool for population genetics as well as for epidemiological studies of ETEC.

Genotypic and phenotypic characterization of enterotoxigenicEscherichia coli(ETEC) strains isolated in Rio de Janeiro city, Brazil

“…In well-standardized experimental conditions, RAPD-PCR showed a consistent correlation with PFGE and MLEE analysis. It was fast, reproducible and stable, and can be considered as an informative tool for the genetic characterization of ETEC strains [19].…”

Diversity and antimicrobial activity of Pseudovibrio spp. from Irish marine sponges

“…Random amplification of polymorphic DNA (RAPD) analysis was carried out as previously described (Pacheco et al 1997) using 5 ng of genomic DNA from each Pseudovibrio isolate as template. Reactions (25 ll) were carried out in 1X Green Go-Taq reaction buffer (Promega) supplemented with MgCl 2 to a final concentration of 3 mmol l )1 and containing 30 pmol of primer 1254 (5¢-CCGCAGCCAA-3¢).…”

Clonal Nature of Enterotoxigenic Escherichia coli Serotype O6:H16 Revealed by Randomly Amplified Polymorphic DNA Analysis

“…We have previously reported the application of random amplification of polymorphic DNA (RAPD) to investigate the genetic relationship among ETEC strains (11). We observed that isolates sharing the same serotype as well as other phenotypic traits had similar amplification patterns, indicating that RAPD profiles were useful in revealing clonal groups among these organisms.…”