Table 1.

Characteristics of the natural mutator E. coliisolates and their derivative strains

StrainOriginRiframut genotypePhylogenetic groupbPresence (+) or absence (−) of extraintestinal virulence determinants:Lethality in micec (%)Virulence phenotyped
K1 antigensfa/focpapafahlycnfaeribe10Total no.
TIM28Pus5.9 × 10−6 mutLmutantA00/20 (0)Typical
IAI77UTIe 2.62 × 10−7 NDf B2++++426/50 (52)Atypical
SA2077UTI5 × 10−7 mutLmutantA+111/20 (55)Atypical
ECOR 48UTI8.8 × 10−7 mutSmutantD++++43/20 (15)Atypical
IAI68UTI5 × 10−7 NDB2+++326/50 (52)Atypical
SA1902UTI3.25 × 10−6 mutSmutantB2+++31/20 (5)Atypical
M13Feces6.6 × 10−7 mutSmutantB105/20 (25)Atypical
M13/pBR322This study9 × 10−7 mutSmutant22/52 (42)
M13/pBA40This study3.4 × 10−8 mutS + 27/52 (52)
SA1923UTI4.7 × 10−6 mutSmutantD+++++50/20 (0)Atypical
SA1923/pBR322This study1.57 × 10−6 mutSmutant0/10 (0)
SA1923/pBA40This study2.73 × 10−8 mutS + 0/10 (0)
  • a Frequency of mutations to rifampin resistance.

  • b Phylogenetic groups are indicated as given in Herzer et al. (11).

  • c Lethality in mice is indicated as the number of mice killed/number of inoculated mice and as the percentage of inoculated mice that died.

  • d Atypical virulence phenotype is defined as strains with no to one virulence determinant that kill mice or as strains with three to five virulence determinants that are avirulent or kill mice at an intermediate level.

  • e UTI, urinary tract infection.

  • f ND, not determined.