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Title: SINGLE NUCLEOTIDE POLYMORPHISMS IN THE RFB LOCUS OF ESCHERICHIA COLI O157 STEC AND NON-STEC ISOLATES

Author
item Bono, James - Jim
item Keen, James
item Laegreid, William

Submitted to: International Symposium and Workshop on Shiga Toxin ... Escherichia coli
Publication Type: Abstract Only
Publication Acceptance Date: 2/28/2003
Publication Date: 6/9/2003
Citation: BONO, J.L., KEEN, J.E., LAEGREID, W.W. SINGLE NUCLEOTIDE POLYMORPHISMS IN THE RFB LOCUS OF ESCHERICHIA COLI O157 STEC AND NON-STEC ISOLATES. INTERNATIONAL SYMPOSIUM AND WORKSHOP ON SHIGA TOXIN ... ESCHERICHIA COLI. 2003. Abstract No. P77.

Interpretive Summary:

Technical Abstract: E. coli serotype O157 is a diverse group of bacteria. Although the genetic arrangement of the rfb locus, which synthesizes the O157 O antigen serotype, is conserved the remainder of the genomic contents can vary between different H antigens and virulence factors. One way of classifying E. coli O157 is based upon its genetic contents. Shiga toxin-containing E. coli O157 (STEC) is a group of bacteria which can cause severe disease in humans and have the H7 genotype. Non-STEC O157 E. coli have a variety of H antigen types, but don't have shiga toxin genes. In order to estimate the sequence divergence at the rfb locus between STEC and non-STEC O157 isolates, a 1188 bp fragment of the O157 rfb locus was sequenced from 96 STEC O157:H7/NM isolates and 10 non-STEC O157 isolates. Thirty-one single nucleotide polymorphisms were distributed over the 1188 bp region resulting in a minimum of 99.3% nucleotide identity among the isolates sequence. One polymorphic site defined two alleles with STEC O157 isolates belonging to allele A and non-STEC O157 isolates belonging to allele B. Of the sixteen polymorphic sites identified in allele A isolates only one was a nonsynonymous mutation while five of the fifteen polymorphic sites in allele B isolates were nonsynonymous. These results support previous findings of allelic differences between STEC O157 and non-STEC O157 in conserved genes but also indicate the clonality of STEC O157 and the diversity of non-STEC O157.