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Use of a multi-locus approach to determine the phylogenetic position of 5 unidentified Mycobacterium strains isolated from clinical samples

Abstract number: P1551

Mignard S., Flandrois J.

Molecular sequencing and genomic studies have accumulated evidence for the definition of species concept. 16SrRNA is inadequate for a complete resolution of species of Bacteria. The Multilocus Approach appears to be useful for the classification of Bacteria. We wanted to perform a MLSA study on the Mycobacterium genes and applied this method to strain remained unidentified by the 16S rRNA sequencing.

Methods: we worked on the whole type strain collection of the genus Mycobacterium, sequenced 7 genes (16S rRNA, hsp65, rpoB, sodA, smpB, tuf, ssrA) and created a phylogeny on the concatenated sequence by Maximum Likelihood method (better tolerance of missing data). We submitted the 7-genes concatenated sequence of each unknown strain and reanalysed the global alignment by PHYML.

Results: the phylogeny constructed by ML was the first one on this genus and resulted in the usual topology with early separation of the rapidly growing group and of the slowly growing group. Usual pathogens clusters are well grouped. Applying the analysis on the 5 clinical isolates that remained unidentified, the MLSA approach confirmed the up-to-now undescribed status of strains.

Conclusion: As recommended by the Stackebrandt Committee, the MLSA approach is a useful tool for better resolving species and necessary for description of new species. And even if this approach still remains too expensive for a routine use, it might constitute an interesting trend for bacterial identification when the resolving power of the 16S rRNA is insufficient.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Subject:
Location: Barcelona, Spain
Presentation type:
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