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Clinical and Diagnostic Laboratory Immunology, March 2000, p. 265-273, Vol. 7, No. 2
VA Medical Center and Department of Medicine,
University of Minnesota, Minneapolis, Minnesota
Received 6 August 1999/Returned for modification 3 November
1999/Accepted 7 December 1999
Repetitive-element PCR (rep-PCR) fingerprinting is a promising
molecular typing tool for Escherichia coli, including for
discriminating between pathogenic and nonpathogenic clones, but is
plagued by irreproducibility. Using the ERIC2 and BOXA1R primers and 15 E. coli strains from the ECOR reference collection (three
from each phylogenetic group, as defined by multilocus enzyme
electrophoresis [MLEE], including virulence-associated group B2),
we rigorously assessed the effect of extremely elevated annealing
temperatures on rep-PCR's reproducibility, discriminating
power, and ability to reveal MLEE-defined phylogenetic relationships.
Modified cycling conditions significantly improved assay
reproducibility and discriminating power, allowing fingerprints from
different cyclers to be analyzed together with minimal loss of
resolution. The correspondence of rep-PCR with MLEE with respect to
tree structure and regression analysis of distances was substantially
better with modified than with standard cycling conditions.
Nonetheless, rep-PCR was only a fair surrogate for MLEE, and when
fingerprints from different days were compared, it failed to
distinguish between different clones within all-important phylogenetic
group B2. These findings indicate that although the performance and
phylogenetic fidelity of rep-PCR fingerprinting can be improved
substantially with modified assay conditions, even when so improved
rep-PCR cannot fully substitute for MLEE as a phylogenetic typing
method for pathogenic E. coli.
1071-412X/00/$04.00+0
Improved Repetitive-Element PCR Fingerprinting for
Resolving Pathogenic and Nonpathogenic Phylogenetic Groups within
Escherichia coli
*
Corresponding author. Mailing address: Infectious
Diseases (111F), VA Medical Center, One Veterans Dr., Minneapolis, MN
55417. Phone: (612) 725-2000, ext. 4185, Fax: (612) 725-2273. E-mail: johns007{at}tc.umn.edu.
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