Table 3.

Comparison of virulence-associated traits of UPEC O6 strains 536 and CFT073

536 (B2, ST 92; O6:K15:H31)CFT073 (B2, ST 73; O6:K2:H1)
Smooth phenotype (long-chain LPS)++
Serum resistance++
Adhesion to T24 cells139 ± 57123 ± 51
Adhesion to RT112 cells133 ± 5676 ± 68
Invasion rate into T24 cells, %3.2 ± 2.80.7 ± 0.6
Invasion rate into RT112 cells, %1.7 ± 0.70.3 ± 0.3
Enterochelin (Ent)++
Salmochelin (Iro)++
Salmonella iron transport (Sit)+
Aerobactin (Iuc)+
Yersiniabactin (Ybt)+*
Hemin uptake system (Chu)++
No. of putative fimbrial operons1413
No. of autotransporters911
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: 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.