Time to positivity of blood cultures for children with Streptococcus pneumoniae bacteremia

We report on a 3-year (1 January 1996 through 31 December 1999) retrospective chart review of children with Streptococcus pneumoniae bacteremia to identify the time to identification of growth of S. pneumoniae in blood culture and to attempt to identify clinical predictors of early versus late growth of S. pneumoniae in culture. The time to detection of S. pneumoniae in blood culture for immunocompetent patients ranged from 4.4 to 25.9 hours (h), with a mean of 11.5 h (standard deviation, 2.8). There was no difference in the time to detection for immunocompromised versus immunocompetent patients. The 10th and 90th deciles for time to detection among immunocompetent patients were 9.2 and 14.0 h, respectively. There were no differences in white blood cell count, absolute neutrophil count, or height of fever between the lowest and highest decile groups. Ninety percent of blood cultures yielding S. pneumoniae are noted positive within 14 h, and no clinical or laboratory parameters accurately predicted early versus late growth of S. pneumoniae in blood culture.