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This Article Full Text (Papers in Press[PDF]) All Versions of this Article: jmm.0.007187-0v1 58/7/884    most recent Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Google Scholar Articles by Clark, C. G Articles by Tabor, H. PubMed PubMed Citation Articles by Clark, C. G Articles by Tabor, H. Agricola Articles by Clark, C. G Articles by Tabor, H.

Escherichia coli O123 O antigen genes and polysaccharide structure are conserved in some Salmonella enterica serogroups

¹ National Microbiology Laboratory, Public Health Agency of Canada;

² Public Health Agency of Canada;

³ retired;

⁴ Laboratory for Foodborne Zoonoses, Public Health Agency of Canada;

⁵ retired, formerly Laboratory for Foodborne Zoonoses, Public Health Agency of Canada

⁶ E-mail: clifford_clark{at}phac-aspc.gc.ca

Received October 6, 2008
Accepted March 23, 2009

The serotyping of O and H antigens is an important first step in the characterization of Salmonella enterica. However, serotyping has become increasingly technically demanding and expensive to perform. We have therefore sequenced additional S. enterica O antigen gene clusters to provide information for the development of DNA-based serotyping methods. Three S. enterica isolates had O antigen gene clusters with homology to the Escherichia coli O123 O antigen region. O antigen clusters from two serogroup 058 S. enterica strains had approximately 85% identity with the E. coli 0123 O antigen region over their entire length, suggesting that these Salmonella and E. coli O antigen regions evolved from a common ancestor. The O antigen cluster of a Salmonella serogroup O41 isolate had a lower level of identity with E. coli O123 over only part of its O antigen DNA cluster sequence, suggesting a different and more complex evolution of this gene cluster than those in the O58 strains. A large part of the Salmonella O41 O antigen DNA cluster had very close identity with the O antigen cluster of an O62 strain. This region of DNA homology included the wzx and wzy genes. Therefore, molecular serotyping tests using only the O41 or O62 wzx and wzy genes would not differentiate between the two serogroups. The E. coli O123 O-antigenic polysaccharide and its repeating unit were characterized, and the chemical structure for E. coli O123 was entirely consistent with the O antigen gene cluster sequences of E. coli O123 and the Salmonella O58 isolates. An understanding of both the genetic and structural composition of Salmonella and E. coli O antigens is necessary for the development of novel molecular methods for serotyping these organisms.