Rapid and high resolution genotyping of all Escherichia coli serotypes using 10 genomic repeat-containing loci

Division of Infectious Diseases control, Norwegian Institute of Public Health, Lovisenberggata 8, P.O. Box 4404 Nydalen, N-0403 Oslo, Norway.
Journal of microbiological methods (Impact Factor: 2.03). 11/2011; 88(1):134-9. DOI: 10.1016/j.mimet.2011.11.003
Source: PubMed


Our laboratory has previously published two multiple-locus variable-number tandem-repeats analysis (MLVA) methods for rapid genotyping of Escherichia coli (E. coli), which are now in routine use for surveillance and outbreak detection. The first assay developed was specific for E. coli O157:H7; however this assay was not suitable for genotyping other E. coli serotypes. A new generic MLVA-assay was then developed with the capability of genotyping all E. coli serotypes. This generic E. coli MLVA (GECM7) was based on polymorphism in seven variable number of tandem repeats (VNTR) loci. GECM7 worked well with the majority of E. coli serotypes; however we wanted to increase the resolution for this method based in part of comparison with PFGE typing of E. coli O26:H11, where PFGE appeared to display higher resolution. The GECM7 method was improved by adding three new repeat-loci to a total of ten (GECM10), and a considerable increase in resolution was observed (from 296 to 507 genotypes on the same set of strains).

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Available from: Kjersti Haugum, Nov 24, 2014
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    • "STEC O157 strains were analyzed by an 11-loci MLVA method described previously (Cooley et al., 2010). Non-O157 STEC strains were analyzed by the 10-loci MLVA method which includes 7 loci initially described for E. coli (Lindstedt et al., 2007; Cooley et al., 2013) and 3 additional loci including a CRISPR locus (Løbersli et al., 2012). Briefly, overnight cultures were boiled and aliquots were used as template in multiplex PCR reactions with fluorescently labeled primers to amplify fragments containing tandem repeats. "
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