sábado, 11 de junio de 2011

New clues found in tracing the origin of E coli O104

BGI and collaborators announce new clues found in tracing the origin of the deadly E. coli strain and appeal for the sharing of additional data

Different sources have reported that two strains, 01-09591 from Germany isolated in 2001 and 55989 from Central Africa in 2002 are highly similar to the 2011 outbreak strain. Based on the most recently curated assembly publically released by the BGI, these strains have an identical Multi Locus Sequence Typing (ST678) based on analysis of 7 important “housekeeping” genes.

This evidence allow tracing the history of the bacteria, as this latest analysis indicates that the two German strains (01-09591 originally isolated in 2001 and TY2482 from the 2011 outbreak) have identical profiles for all 12 virulence/fitness genes and 7 MLST housekeeping genes. However, at some point over this 10-year period the new 2011 outbreak strain seems to have developed the ability to resist many additional types of antibiotics. The latest data is now pointing to this candidate, as it now seems the African strain (strain 55989) is genetically more “distant” as the Shiga-toxin-producing gene and tellurite-resistance-genes were shown to be absent.

This latest evidences that the previously 2001 German strain is the most likely ancestor of the 2011 outbreak strain. This may imply that fast evolution resulted in the gain of more genes during the last 10 years. Further comparisons between the genomes of these bacteria will greatly help clarify why the latest outbreak has been so exceptionally pathogenic on this occasion.

The origin of the E. coli EHEC O104:H4 is not yet known. One may however remember that a strain with a similar surface antigen was isolated in Germany in 2001. Knowing the kinship between the present strain and the older one will be of the utmost importance.
Source: http://www.genomics.cn/en/news_show.php?type=show&id=649

Fernando Fuentes Pinochet

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