Table 3.
Comparison of virulence-associated traits of UPEC O6 strains 536 and CFT073
| Characteristics | Strains |
|
|---|---|---|
| 536 (B2, ST 92; O6:K15:H31) | CFT073 (B2, ST 73; O6:K2:H1) | |
| Hemolysis | ++ | + |
| Smooth phenotype (long-chain LPS) | + | + |
| Capsule | + | + |
| Serum resistance | + | + |
| Motility | + | + |
| Adhesion to T24 cells | 139 ± 57 | 123 ± 51 |
| Adhesion to RT112 cells | 133 ± 56 | 76 ± 68 |
| Invasion rate into T24 cells, % | 3.2 ± 2.8 | 0.7 ± 0.6 |
| Invasion rate into RT112 cells, % | 1.7 ± 0.7 | 0.3 ± 0.3 |
| Enterochelin (Ent) | + | + |
| Salmochelin (Iro) | + | + |
| Salmonella iron transport (Sit) | – | + |
| Aerobactin (Iuc) | – | + |
| Yersiniabactin (Ybt) | + | −* |
| Hemin uptake system (Chu) | + | + |
| No. of putative fimbrial operons | 14 | 13 |
| No. of autotransporters | 9 | 11 |
| Biofilm formation (polyethylene) | + | + |
| Intravenous infection, cfu (LD50 values) | 2.6 × 108 | 6 × 108 |
Strains 536 and CFT073 belong to ECOR group B2. Sequence type (ST) was determined according to multi locus sequence typing (MLST) as described on the following web site: http://web.mpiib-berlin.mpg.de/mlst/dbs/Ecoli/documents/primersColi_html. 06:K15:H31 and O6:K2:H1 are the serotypes of 536 and CFT073, respectively. For adhesion to both T24 and RT112 cells, bacteria were quantified in microtiter plate adhesion assays as adherent bacteria per well × 100. For the invasion rate into T24 and RT112 cells, bacteria were quantified as the percentage of the inoculum used for infection. LD50 values were determined as described in the text.
*The yersiniabactin determinant is nonfunctional because of frameshift mutations in several ORFs.