Article Figures & Data
Figures
- Fig. 1.
IS629 presence/absence in the stepwise evolutionary model of E. coli O157:H7 from ancestral O55:H7 strains (representation modified from reference 4). The circles represent the different clonal complexes. IS629 presence and absence is indicated in bold by +IS629 and −IS629, respectively. Strains belonging to hypothetical CC A3 have not yet been isolated.
- Fig. 2.
Schematic representations of the plasmid construct pIS629AB-Tc and determination of the transposition frequency. (A) Plasmid construct pIS629AB-Tc, containing the IS629 transposase gene (ORFab) and a tetracycline resistance gene (tetC) disrupting the ampicillin (Ampr) gene. (B) Successful transposition results in ampicillin-resistant colonies (transposition-positive phenotype). Cells showing no transposition remain tetracycline resistant only (original phenotype). Excision frequency was calculated as follows: Ampr/Tetr cells.
Tables
- Table 1.
Characteristics of E. coli strains used in this study and IS629-Tc excision frequencies from pIS629AB-Tc in each strain, grouped according to CC, from recent O157 to ancestral O55 serotypesd
Strain name Serotype CCa IS629b Excision frequencyc Avg SD EDL933 O157:H7 A6 + 1.3 × 10−3 ± 0.4 × 10−3 G5101 O157:H7 A5 + 1.6 × 10−3 ± 0.2 × 10−3 LSU-61 O157:H7 A? tr 0.6 × 10−3 ± 0.2 × 10−3 493-89 O157:H− A4 − 2.6 × 10−6 ± 0.9 × 10−6 H56929c O157:H− A4 − 2.2 × 10−6 ± 0.3 × 10−6 H1085c O157:H− A4 − 2.3 × 10−6 ± 0.4 × 10−6 3256-97 O55:H7 A2 − 1.5 × 10−8 ± 0.6 × 10−8 DEC5A O55:H7 A1 + 2.2 × 10−7 ± 0.1 × 10−7
