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International Journal of Microbiology
Volume 2012 (2012), Article ID 140105, 10 pages
Research Article

Polymorphic Amplified Typing Sequences and Pulsed-Field Gel Electrophoresis Yield Comparable Results in the Strain Typing of a Diverse Set of Bovine Escherichia coli O157:H7 Isolates

1Food Safety and Enteric Pathogens Research Unit, National Animal Disease Center, Agricultural Research Service, U.S. Department of Agriculture, Ames, IA 50010, USA
2Department of Microbiology, Molecular Biology and Biochemistry, University of Idaho, Moscow, ID 83843, USA
3Department of Veterinary Microbiology and Pathology, College of Veterinary Medicine, Washington State University, Pullman, WA 99164, USA
4Division of Infectious Diseases, Massachusetts General Hospital, Boston, MA 02114, USA
5Department of Epidemiology, Harvard School of Public Health, Boston, MA 02115, USA
6Department of Medicine, Harvard Medical School, Boston, MA 02115, USA
7Pathovacs Inc., Ames, IA 50010, USA
8School of Food Sciences, University of Idaho, Moscow, ID 83843, USA
9Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115, USA

Received 25 June 2012; Accepted 25 July 2012

Academic Editor: Giuseppe Comi

Copyright © 2012 Indira T. Kudva et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Polymorphic amplified typing sequences (PATS), a PCR-based Escherichia coli O157:H7 (O157) strain typing system, targets insertions-deletions and single nucleotide polymorphisms at XbaI and AvrII restriction enzyme sites, respectively, and the virulence genes (stx1, stx2, eae, hlyA) in the O157 genome. In this study, the ability of PATS to discriminate O157 isolates associated with cattle was evaluated. An in-depth comparison of 25 bovine O157 isolates, from different geographic locations across Northwest United States, showed that about 85% of these isolates shared the same dendogram clade by PATS and pulsed-field gel electrophoresis (PFGE), irrespective of the restriction enzyme sites targeted. The Pearson’s correlation coefficient, r, calculated at about 0.4, 0.3, and 0.4 for XbaI-based, AvrII-based and combined-enzymes PATS and PFGE similarities, respectively, indicating that these profiles shared a good but not high correlation, an expected inference given that the two techniques discriminate differently. Isolates that grouped differently were better matched to their locations using PATS. Overall, PATS discriminated the bovine O157 isolates without interpretive biases or sophisticated analytical software, and effectively complemented while not duplicating PFGE. With its quick turnaround time, PATS has excellent potential as a convenient tool for early epidemiological or food safety investigations, enabling rapid notification/implementation of quarantine measures.