[Clinical outcome and bacterial characteristics of 99 Escherichia coli meningitis in young infants].

To conduct a descriptive analysis of clinical, biological and prognostic aspects of Escherichia coli meningitis in young infants. Clinical and biological data on young infants diagnosed with neonatal E. coli meningitis (NECM) between 1988 and 2004 were collected retrospectively and analyzed with respect to the isolates'phenotypic and genotypic characteristics. The molecular analyses focused on the phylogenetic group, the sequence-O-type, and genetic virulence traits. The virulence of lethal strains was tested in a newborn rat meningitis model. The median age of the 99 children analyzed was 10 days (0 to 90 days), and 83 of the patients were newborns. Thirty-three children were premature. Hyper- or hypothermia was the most frequent clinical sign at admission. Intercurrent urinary tract infection was present in 28% of cases, all over 6 days of age. 81% of blood cultures were positive. The CSF cytology was abnormal in 97% of cases. Twelve hours after admission, 34% of infants were transferred to intensive care. One-third of transfontanellar ultrasound scans done on admission were abnormal. CSH sterilization was slow in 15 % of cases, despite appropriate antibiotic therapy. The use of ciprofloxacin was associated with more rapid CSF sterilization (94 % vs 77 %, p=0.03). Six children relapsed. The average follow-up was eight months, and 21 % of children had sequelae. The case lethality rate was 14%. Fatal outcome was associated with signs of septic shock (57% vs 3%, p<10(-4)) and neurological failure (76% vs 19%, p<10(-4)) within the first 24 hours, and with abnormalities on the first ultrasound scan (63% vs 27%, p=0.03). The risk of death was higher among children infected by strains belonging to unusual sequence-O-types (50% vs 18%, p=0.01), which harbored fewer virulence factors (4.8 vs 5.9, p<10(-4)). Only aerobactin was less frequent in lethal strains (71 % vs 94%, p=0.02). Strains belonging to unusual sequence-O-types and that were lethal in the animal model induced a significantly lower level of bacteremia than strains belonging to frequent sequence-O-types (p<0.001). E. coli meningitis remains highly lethal in infants. Clinical and molecular analyses showed a link between lethality and infrequent sequence-O-types. The avirulence of these strains in animal models suggests that fatal outcome could be due to host susceptibility more than to strain virulence.