Intrahost Genome Alterations in Enterohemorrhagic Escherichia coli Alexander Mellmann, Martina Bielaszewska, Helge Karch  Gastroenterology  Volume 136, Issue 6, Pages 1925-1938 (May 2009) DOI: 10.1053/j.gastro.2008.12.072 Copyright © 2009 AGA Institute Terms and Conditions

Figure 1 Clinical course of infection by EHEC O157:H7 in children. After ingestion of the pathogen and incubation period patients develop watery diarrhea that typically is accompanied by abdominal pain. Then, after a 2- to 4-day interval, bloody diarrhea ensues. This bloody diarrhea, which occurs in about 80% of cases, is the origin of the term hemorrhagic colitis. Approximately 1 week after the onset of diarrhea, 10%–15% of patients younger than 10 years of age develop HUS. Adapted from Tarr et al.43 Gastroenterology 2009 136, 1925-1938DOI: (10.1053/j.gastro.2008.12.072) Copyright © 2009 AGA Institute Terms and Conditions

Figure 2 Schematic presentation of virulence profiles of stx−/eae+ E coli (EHEC-LST) from patients with bloody diarrhea or HUS and of EHEC of the corresponding serotypes. The right side of the graph shows all genes that were investigated. In each serotype, the genes that were present are depicted; identical (or similar) sizes of the graphic fields representing individual genes indicate that the proportions of EHEC-LST and EHEC strains containing the gene were identical (or very close). Gastroenterology 2009 136, 1925-1938DOI: (10.1053/j.gastro.2008.12.072) Copyright © 2009 AGA Institute Terms and Conditions

Figure 3 Multilocus sequence typing analysis of stx−/eae+ E coli (EHEC-LST) strains from patients with bloody diarrhea or HUS and EHEC isolated from patients with these clinical outcomes. EHEC isolates from HUS patients are represented by the HUS-associated EHEC (HUSEC)-collection.121 (A) Minimum-spanning tree based on the HUSEC strains, EHEC-LST,85,86 and Shigella dysenteriae M1354 (ST243, data from the E coli MLST website [available: http://web.mpiib-berlin.mpg.de/mlst/dbs/Ecoli]) as an outgroup generated from allelic profiles based on the Based Upon Related Sequence Types (BURST) algorithm.122 Each sequence type is represented by a circle named with its ST. The numbers on the connecting lines represent the number of differing alleles from the in total 7 house-keeping genes of the multilocus sequence typing scheme. The color(s) of the circle illustrate the pathotype; clonal complexes (cc) are, if applicable, shaded in grey and named in accordance to the E coli multilocus sequence typing website. (B) Distribution of the 7 house-keeping genes used for multilocus sequence typing analysis on the EDL933 EHEC O157:H7 genome. Gastroenterology 2009 136, 1925-1938DOI: (10.1053/j.gastro.2008.12.072) Copyright © 2009 AGA Institute Terms and Conditions

Figure 4 Molecular basis for loss of stx-encoding bacteriophages by EHEC leading to the conversion of EHEC to their stx-negative derivatives, EHEC-LST. (A) Lysogenic conversion of an EHEC strain with a stx-harboring prophage. The phage integration site (yecE) and positions of the genes encoding Shiga toxin A and B subunits (stxAB), and genes involved in the maintenance of the lysogenic state and in the phage chromosomal excision (Q, S/R/Rz, pR, tR, cI, cII, cro) are depicted. In its lysogenic cycle, the stx phage replicates as a part of the bacterial chromosome. On induction with stimuli triggering SOS response, the prophage is excised from the genome and enters the lytic cycle, which leads to the host cell lysis or to the conversion to EHEC-LST of surviving cells. (B) Example of a polymerase chain reaction (pcr) strategy to test the occupancy of a stx phage integration site. Row stx2, PCR targeting stx2 gene; row yecE, PCR targeting an intact yecE locus (a stx2 phage integration site). In EHEC strains that harbor a stx2 phage, yecE is occupied by the phage, leading to a negative result of the yecE PCR. Loss of the stx2 phage (EHEC-LST) leads to vacating the yecE locus and thus to the appearance of the yecE amplicon. Gastroenterology 2009 136, 1925-1938DOI: (10.1053/j.gastro.2008.12.072) Copyright © 2009 AGA Institute Terms and Conditions

Figure 5 Temporal shift of stx genotypes in EHEC O26:H11 isolated in Germany. Although from 1965 to 1995 most EHEC O26 clinical isolates contained the stx1 gene (mostly alone, rarely together with stx2), a large increase in the prevalence of strains that possessed stx2 as the sole stx gene was observed since the late 1990s. The stx2-harboring clone of EHEC O26:H11 plausibly arose by introducing a stx2 phage into the E coli O26:H11 population that lost the original stx1 phage. Gastroenterology 2009 136, 1925-1938DOI: (10.1053/j.gastro.2008.12.072) Copyright © 2009 AGA Institute Terms and Conditions

Alexander Mellmann Gastroenterology 2009 136, 1925-1938DOI: (10.1053/j.gastro.2008.12.072) Copyright © 2009 AGA Institute Terms and Conditions

Martina Bielaszewska Gastroenterology 2009 136, 1925-1938DOI: (10.1053/j.gastro.2008.12.072) Copyright © 2009 AGA Institute Terms and Conditions

Helge Karch Gastroenterology 2009 136, 1925-1938DOI: (10.1053/j.gastro.2008.12.072) Copyright © 2009 AGA Institute Terms and Conditions