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Table 4 Characterization of E. coli ST131 O25:H4/H30-Rx strains with traits of the AIEC pathotype

From: Adherent/invasive Escherichia coli (AIEC) isolates from asymptomatic people: new E. coli ST131 O25:H4/H30-Rx virotypes

Strain Adherence ratea Invasion rateb Survival within macrophagesc Biofilm formation rated
C7223 60.4 b/c 1.8 × 102 3.3 × 102 48.13
C7225 17.3 b/c 1.2 × 108 2.3 × 105 51.44
C7236 18.9 b/c 1.4 × 108 2.0 × 105 46.9
C7230 12.6 b/c 3.2 × 104 4.4 × 103 46.47
  1. Determination of E. coli strains as belonging to the AIEC pathotype was performed using the following criteria: (1) the ability to adhere to HeLa cells with an adhesion index equal or superior to 1 bacteria per cell (b/c), (2) the ability of the bacteria to invade HeLa cells with an invasion index equal or superior to 0.1% of the original inoculum, (3) the ability to survive and to replicate within J774 macrophages
  2. aAdherence rate is expressed as the mean of bacteria adhered to one HeLa cell
  3. bInvasion is the mean CFUs after 1 h rifampicin treatment of infected HeLa cells
  4. cMean of intracellular bacteria at 3 h post infection relative to the number after 1 h rifampicin treatment, defined as 100% (MOI of 100)
  5. dBiofilm formation rate is defined as milligrams per grams of total protein