Typing of the Shiga toxin - Producing Escherichia coli strains isolated from diarrheic children using Multi Locus Sequence Typing (MLST)

Shiga toxin-producing Escherichia coli (STEC) may also be referred to as Escherichia coli pathotypes, since E. coli serogroups O26 and O157 are frequently implicated in outbreaks of diarrhea in children. This study aimed to analyze the clone relationship of Shiga toxin-producing E. coli serogroups O157 and O26 isolated from diarrhea in children less than 60 months by Multilocus Sequence Typing (MLST) method. A total of 20 Shiga toxins-producing E. coli (STEC strains were selected from two serogroups O26 and O157 isolated from diarrheic children, and the PCR products from amplification of seven housekeeping genes were sequenced in them. The nucleotide sequences of each gene in each isolate were analyzed, then queried to the MLST database and, in addition, determination of allele-specific of each gene were determined of sequence types (ST). A total of 3 clones ST10, ST11 and ST21 were identified from 20 isolates, which identified three gene clusters A, B and C, respectively. Despite of the different ST were found in our isolates studied. There was no a high genetic diversity among the two serogroup O26 and O157 isolates, which indicates the clone relationship between E. coli isolates circulating in Tehran.