Routine quantitative blood cultures in children with Haemophilus influenzae or Streptococcus pneumoniae bacteremia.

The potential clinical value of quantitative blood cultures determined by a commercially available lysis-direct plating method was studied in 50 children with either Haemophilus influenzae or Streptococcus pneumoniae bacteremia. The magnitude of bacteremia correlated with the severity of the infection; patients with greater than or equal to 100 colony-forming units per milliliter were significantly more likely to have meningitis (P less than .01, chi 2 = 7.5). On the other hand, all patients with S. pneumoniae bacteremia with colony counts lower than 15 colony-forming units per milliliter had "occult bacteremia" with no focus of infection. The data suggest that patients with higher levels of bacteremia have more severe disease. Quantitative blood culture results may be helpful in identifying which children are at risk for invasive disease.