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Infection and Immunity, March 2000, p. 1116-1124, Vol. 68, No. 3
Department of Microbiology, University of
Guelph, Guelph, Ontario N1G 2W1,1 and
Guelph Laboratory, Health Canada, Guelph, Ontario N1G
3W4,2 Canada
Received 29 July 1999/Returned for modification 21 September
1999/Accepted 29 November 1999
In the lipopolysaccharides of Escherichia coli there
are five distinct core oligosaccharide (core OS) structures, designated K-12 and R1 to R4. The objective of this work was to determine the
prevalences of these core OS types within the species. Unique sequences
in the waa (core OS biosynthesis) gene operon were used to
develop a PCR-based system that facilitated unequivocal determination of the core OS types in isolates of E. coli. This
system was applied to the 72 isolates in the E. coli ECOR
collection, a compilation of isolates that is considered to be broadly
representative of the genetic diversity of the species. Fifty (69.4%)
of the ECOR isolates contained the R1 core OS, 8 (11.1%) were
representatives of R2, 8 (11.1%) were R3, 2 (2.8%) were R4, and only
4 (5.6%) were K-12. R1 is the only core OS type found in all four
major phylogenetic groups (A, B1, B2, and D) in the ECOR collection. Virulent extraintestinal pathogenic E. coli isolates tend
to be closely related to group B2 and, to a lesser extent, group D
isolates. All of the ECOR representatives from the B2 and D groups had
the R1 core OS. In contrast, commensal E. coli isolates are
more closely related to group A, which contains isolates representing
each of the five core OS structures. R3 was the only core OS type found in 38 verotoxigenic E. coli (VTEC) isolates from humans and
cattle belonging to the common enterohemorrhagic E. coli
serogroups O157, O111, and O26. Although isolates from other VTEC
serogroups showed more core OS diversity, the R3 type (83.1% of all
VTEC isolates) was still predominant. When non-VTEC commensal isolates
from cattle were analyzed, it was found that most possessed the R1 core
OS type.
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Copyright © 2000, American Society for Microbiology. All rights reserved.
Distribution of Core Oligosaccharide Types in
Lipopolysaccharides from Escherichia coli

*
Corresponding author. Mailing address: Department of
Microbiology, University of Guelph, Guelph, Ontario N1G 2W1, Canada. Phone: (519) 824-4120, ext. 3478. Fax: (519) 837-1802. E-mail: cwhitfie{at}uoguelph.ca.
Present address: Department of Microbiology and Immunology,
University of Western Ontario, London, Ontario N6A 5C1, Canada.
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