New system for multilocus variable-number tandem-repeat analysis of the enterohemorrhagic Escherichia coli strains belonging to three major serogroups: O157, O26, and O111
Article first published online: 7 JUL 2010
© 2010 The Societies and Blackwell Publishing Asia Pty Ltd
Microbiology and Immunology
Volume 54, Issue 10, pages 569–577, October 2010
How to Cite
Izumiya, H., Pei, Y., Terajima, J., Ohnishi, M., Hayashi, T., Iyoda, S. and Watanabe, H. (2010), New system for multilocus variable-number tandem-repeat analysis of the enterohemorrhagic Escherichia coli strains belonging to three major serogroups: O157, O26, and O111. Microbiology and Immunology, 54: 569–577. doi: 10.1111/j.1348-0421.2010.00252.x
- Issue published online: 7 JUL 2010
- Article first published online: 7 JUL 2010
- Accepted manuscript online: 7 JUL 2010 12:00AM EST
- Received 18 January 2010; revised 22 June 2010; accepted 29 June 2010.
- enterohemorrhagic Escherichia coli;
- multilocus variable-number tandem-repeat analysis;
- serogroup O26;
- serogroup O111
Enterohemorrhagic Escherichia coli (EHEC), a food- and waterborne pathogen, causes diarrhea, hemorrhagic colitis, and life-threatening HUS. MLVA is a newly developed and widely accepted genotyping tool. An MLVA system for EHEC O157 involving nine genomic loci has already been established. However, the present study revealed that the above-mentioned MLVA system cannot analyze EHEC O26 and O111 isolates—the second and third most dominant EHEC serogroups in Japan, respectively. Therefore, with several modifications to the O157 system and the use of nine additional loci, we developed an expanded MLVA system applicable to EHEC O26, O111, and O157. Our MLVA system had a relatively high resolution power for each of the three serogroups: Simpson's index of diversity was 0.991 (95% CI = 0.989–0.993), 0.988 (95% CI, 0.986–0.990), and 0.986 (95% CI, 0.979–0.993) for O26, O111, and O157, respectively. This system also detected outbreak-related isolates; the isolates collected during each of the 12 O26 and O111 outbreaks formed unique clusters, and most of the repeat copy numbers among the isolates collected during the same outbreak exhibited no or single-locus variations. These results were comparable to those of cluster analyses based on PFGE profiles. Therefore, our system can complement PFGE analysis—the current golden method. Because EHEC strains of three major serogroups can be rapidly analyzed on a single platform with our expanded MLVA system, this system could be widely used in molecular epidemiological studies of EHEC infections.