This Article Full Text Full Text (PDF) Supplemental material Other Versions of this Article: JB.00796-07v1 189/21/7808    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Salerno, A. Articles by Brisse, S. Search for Related Content PubMed PubMed Citation Articles by Salerno, A. Articles by Brisse, S.

Recombining Population Structure of Plesiomonas shigelloides (Enterobacteriaceae) Revealed by Multilocus Sequence Typing ^,

Anna Salerno,^1,2,, Alexis Delétoile,^1, Martine Lefevre,¹ Ivan Ciznar,³ Karel Krovacek,⁴ Patrick Grimont,¹ and Sylvain Brisse^1*

Unité Biodiversité des Bactéries Pathogènes Emergentes, Institut Pasteur, 28 rue du Docteur Roux, 75724 Paris Cedex 15, France,¹ Department of Crop Systems, Forestry and Environmental Sciences, University of Basilicata, Potenza, Italy,² Slovak Medical University, Faculty of Public Health, 83303 Bratislava, Limbova 12, Slovak Republic,³ Department of Biomedical Sciences and Veterinary Public Health, Faculty of Veterinary Medicine and Animal Science, SLU, Box 7036, 750 07 Uppsala, Sweden⁴

Received 23 May 2007/ Accepted 1 August 2007

Plesiomonas shigelloides is an emerging pathogen that is widespread in the aquatic environment and is responsible for intestinal diseases and extraintestinal infections in humans and other animals. Virtually nothing is known about its genetic diversity, population structure, and evolution, which severely limits epidemiological control. We addressed these questions by developing a multilocus sequence typing (MLST) system based on five genes (fusA, leuS, pyrG, recG, and rpoB) and analyzing 77 epidemiologically unrelated strains from several countries and several ecological sources. The phylogenetic position of P. shigelloides within family Enterobacteriaceae was precisely defined by phylogenetic analysis of the same gene portions in other family members. Within P. shigelloides, high levels of nucleotide diversity (average percentage of nucleotide differences between strains, 1.49%) and genotypic diversity (64 distinct sequence types; Simpson's index, 99.7%) were found, with no salient internal phylogenetic structure. We estimated that homologous recombination in housekeeping genes affects P. shigelloides alleles and nucleotides 7 and 77 times more frequently than mutation, respectively. These ratios are similar to those observed in the naturally transformable species Streptococcus pneumoniae with a high rate of recombination. In contrast, recombination within Salmonella enterica, Escherichia coli, and Yersinia enterocolitica was much less frequent. P. shigelloides thus stands out among members of the Enterobacteriaceae. Its high rate of recombination results in a lack of association between genomic background and O and H antigenic factors, as observed for the 51 serotypes found in our sample. Given its robustness and discriminatory power, we recommend MLST as a reference method for population biology studies and epidemiological tracking of P. shigelloides strains.

Published ahead of print on 10 August 2007.

Supplemental material for this article may be found at http://jb.asm.org/.

A.S. and A.D. contributed equally to this work.

Present address: Department of Environmental Sciences, Parthenope University of Naples, Via Acton 38, 80122 Naples, Italy.