Risk assessment of commensal Escherichia coli strains

The commensal Escherichia coli strains ED1a and IAI1 were isolated from the stool of healthy humans in France in the 2000s and 1980s, respectively. The complete genome sequences of both strains are available. The E. coli strain ED1a belongs to phylogenetic group B2 and is assigned to serotype O81. Oral ingestion of the ED1a strain does not cause adverse health effects in humans or pigs. The E. coli strain IAI1 belongs to phylogenetic group B1 and is assigned to serotype O8. Data on the strain's viability in the environment or from in vivo human experiments are not available. Like other E. coli K12-derived strains, ED1A and IAI1 are non-pathogenic in the mouse model. The classification of E. coli ED1A and IAI1 in the ZKBS statement takes into account both the available data on their pathogenicity and information on more than 100 typical virulence factor genes. The corresponding genes were selected based on literature reviews on virulence factors of pathogenic E. coli strains, and their presence in the genome of the strains ED1a and IAI1 was examined. This showed that both strains lack most of the virulence factor genes that occur in intestinal pathogenic (IPEC) and extraintestinal pathogenic (ExPEC) E. coli strains. However, individual genes for virulence factors are expressed in both ED1a and IAI1. Based on the available findings and the criteria set out in Section 5 Paragraph 1 of the GenTSV in conjunction with the criteria in Annex 1 of the GenTSV, the ZKBS recommends the classification of E. coli ED1a and IAI1 as donor and recipient organisms for genetic engineering work in the Risk group 1. The reason for this is the absence of a large number of genes for known virulence factors in the genomes of both strains. According to the ZKBS, the mere presence of individual genes for virulence factors in E. coli ED1a and IAI1 does not necessarily equate to pathogenicity. Furthermore, there is a wealth of data for ED1a and IAI1 showing that these two strains are non-pathogenic to humans and animals.

The ZKBS statement can be found at File number 45241.0185 can be retrieved.