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Preliminary evaluation of multiplex PCR-based O157 IS-printing method for subtyping of verocytotoxin-producing Escherichia coli O157

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Preliminary evaluation of multiplex PCR-based O157 IS-printing method for subtyping of verocytotoxin-producing Escherichia coli O157

G. Buvens, O. Soetens, S. Lauwers, D. PiƩrard

Belgian Reference Laboratory for VTEC/EHEC, Department of Microbiology and Infection Control, Universitair Ziekenhuis Brussel, Brussels, Belgium

Background: Verocytotoxin-producing Escherichia coli (VTEC) are frequent causes of bloody diarrhea (BD) and the hemolytic-uremic syndrome (HUS). Whereas more than 200 serotypes have been described, O157:H7/non-motile are the most commonly associated with BD and HUS. Strong phylogenetic similarity between O157 isolates has been shown by genomic cluster analysis. Only highly discriminative but time-consuming techniques like pulsed-field gel electrophoresis (PFGE) and multilocus variable number of tandem repeats analysis (MLVA) are useful for O157 subtyping. For efficient infection control rapid techniques are needed. Ooka et al. recently described a multiplex PCR-based subtyping method based on the variable location of Insertion Sequence 629 (IS629) among VTEC O157 strains (O157 IS-printing) (1).
Objectives: To evaluate O157 IS-printing as compared to PFGE.
Materials and methods: Thirty-seven VTEC O157 isolates were included. O157 IS-printing was applied as described (1). PFGE was performed according to CDC PulseNet protocol for E. coli. Banding patterns were analyzed using GelCompar II.
Results: Using PFGE, indistinguishable band patterns were obtained for 12 O157:H7 isolates associated with an outbreak during the summer of 2008, for 2 isolates from 2 siblings and for 2 O157:H7 recovered from 1 patient, respectively. Twenty-one other epidemiologically unrelated isolates showed distinct band patterns. O157 IS-printing yielded similar clustering as PFGE with the exception of 3 pairs of PFGE distinct isolates that clustered together.
Conclusions: O157 IS-printing can be performed within 5 hours while several days are needed for PFGE, reducing the workload dramatically. No specialized equipment is needed, and a large number of strains can be analyzed simultaneously. Although less discriminative, it is a suitable tool for rapid subtyping of VTEC O157 isolates.
Acknowledgements: Research funded by grant 2007-29 of "Prospective Research for Brussels" program of the Brussels-Capital Region to G.B.

1. Ooka T, Terajima J, Kusumoto M et al. J Clin Microbiol 2009;47:2888-94
Book: International Symposium on Molecular Diagnostics Graz, 3-5/6/2010
Publication year:2010
Keywords:VTEC, O157, IS629 printing
  • ORCID: /0000-0002-4281-9749/work/61725903
  • ORCID: /0000-0002-7756-3691/work/61226139