Objectives
To characterise the genetic and serological diversity of pathogenic <i>Escherichia coli</i>, we tested 111 <i>E coli</i> strains isolated from diarrhoeal patients in Korea between 2003 and 2006.
Methods
The isolates were tested through polymerase chain reaction (PCR) and slide agglutination method for the detection of virulence genes and serotypes, respectively. To compare the expression of Shiga toxin (<i>stx</i>)-1 and <i>stx2</i> genes, real-time quantitative reverse-transcriptase PCR and rapid exprssion assay, reversed-passive latex agglutination, were performed.
Results
Forty-nine Shiga toxin-producing <i>E coli</i> (STEC) strains and 62 non-STEC strains, including 20 enteropathogenic <i>E coli</i>, 20 enterotoxigenic <i>E coli</i>, 20 enteroaggregative <i>E coli</i>, and 2 enteroinvasive <i>E coli</i> were randomly chosen from the strains isolated from diarrhoeal patients in Korea between 2003 and 2006. PCR analysis indicated that locus of enterocyte effacement pathogenicity island, that is, <i>eae</i>A, <i>esp</i>ADB, and <i>tir</i> genes were present in STEC, enteropathogenic <i>E coli</i>, and enteroinvasive <i>E coli</i>. Quorum sensing-related gene <i>lux</i>S was detected in most of pathogenic <i>E coli</i> strains. Major serotypes of the STEC strains were O157 (26%) and O26 (20%), whereas the non-STEC strains possessed various serotypes. Especially, all the strains with serotype O157 carried <i>stx</i>2 and the tested virulence factors. Of the STEC strains, the data of real-time quantitative reverse-transcriptase PCR and reversed-passive latex agglutination tests showed that messenger RNA- and protein expression of <i>stx</i>2 gene were higher than those of <i>stx</i>1 gene.
Conclusion
Our results provide the epidemiological information regarding the trend of STEC and non-STEC infections in the general population and show the fundamental data in association of serotypes with virulence genes in diarrhoeagenic <i>E coli</i> strains from Korea.