 The original strain described by Escherich is believed to be lost, consequently a new type strain (neotype) was chosen as a representative: the neotype strain is U5 / 41T, also known under the deposit names DSM 30083, ATCC 11775, and NCTC 9001, which is pathogenic to chickens and has an O1: K1: H7 serotype. However, in most studies, either O157: H7, K-12 MG1655, or K-12 W3110 were used as a representative E. coli. The genome of the type strain has only lately been sequenced. Particularly the use of whole genome sequences yields highly supported phylogenies. Based on such data, five subspecies of E. coli were distinguished.
