Genomics Research Of Neonatal Meningitis Escherichia Coli Strain CE10

Escherichia coli are one of the important model organisms for microbiology, and are also the ideal model to study the evolution of bacterial genome. Pathogenic E. coli mainly cause gastroenteritis, urinary tract infections, neonatal meningitis and other diseases. NMEC strain CE10(serotype O7:K1, phylogenetic group D) is a pathogenic strain E. coli isolated from cerebrospinal fluid of an infant with neonatal meningitis. Previous studies show that CE10is the only known neonatal meningitis E. coli which carries a complete type â…¢ secretion system.In this study, using Roche/454sequencing technology combined with traditional Sanger sequencing methods, we first complete the whole genome of strain CE10followed by carrying out the study of comparative genomics and phylogenetic analysis. The genome of CE10includes a circular chromosome and4plasmids. The chromosome of CE10(GC content50.6%) encodes5009proteins,91tRNAs and7rRNA operons. Comparative genomic studies show that the chromosome of CE10shares approximately4.1Mb common skeletons with another neonatal meningitis E. coli strain S88, which belongs to phylogenetic group B2, and they maintain a linear consistency. Based on the evolution analyses of whole genome, we find CE10is very close to urinary pathogenic E. coli strain IAI39. However, comparing with IAI39, the chromosome of CE10exist shifts and inversions of large fragments. Thus, we speculate that CE10and IAI39might have only evolved from a common ancestral strain recently but their genome skeletons have undergone significant changes due to niche specific adaptive evolution. Meanwhile, by doing a comprehensive analysis of potential virulent factors of CE10, we find two pathogenic islands associated with type three secretion system(TTSS), ETT2and ETT2*. Proteins expressed by ETT2are the structural proteins of needle complex of TTSS. ETT2*expresses translocator proteins and molecular chaperone of needle complex of TTSS. We also identify a number of potential effectors of TTSS, providing clues for further functional studies.