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Bgi's newest discovery: clues to the origin of deadly ECEH

The bacteria that caused the European outbreak may have originated from the ECEH strain isolated in Germany in 2001, announced by BGI’s newest research on June 5th.

The research team of the institute found that the strains causing this outbreak were highly similar to the German isolates 01-09591 in 2001 and the China-Africa isolates 55989 in 2002 by using multi-site sequencing and typing. The three strains have seven identical "housekeeping genes", which are essential for minimal cell function and are widely used in the classification of bacteria, leading to the conclusion that the three types of escherichia coli are of the same type (ST678).

Based on this discovery, the team investigated the three strains furtherly to trace the source of the outbreak. Analysis of 12 virulence genes/adaptation genes in escherichia coli showed that the 2001 German isolates were identical to this year's outbreak strains, while the China-Africa strains were deficient in shiga toxin genes and tellurite resistance genes compared to the two German strains.

The researchers concluded that the 2001 German strain highly possibly was a direct ancestor of the outbreak. The results of antibiotic resistance tests suggest that after 10 years of evolution, the 2011 strain may have acquired some new genes that make it resistant to more antibiotics.

By comparing the genomes of strains that broke out in 2001 with those that broke out this year, the team says it will greatly help shed light on why the strain that caused the outbreak was so virulent. It will provide the clues of the origin, spread and source of the disease. This will provide stronger support for frontline medical staff to cope with and control the spread of the global epidemic.

The team said the researchers are still in contact to find samples of the 2001 German strain and related information, and continue to carry out further analysis.
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