ABSTRACT
The time to positivity (TTP) of blood culture has significant value for clinicians. However, almost all subjects of previous studies regarding TTP were adults and early infants. Therefore, careful attention is required when referring to previously published data, which might differ according to the age of subjects, as the tendency of infectious focus and pathogens identified from culture vary with age. In this study, we compared the TTP between two pediatric age groups (≤12 months and 13 months to 15 years [>12 months]) at a teaching hospital during a 5-year period. Of the 95 subjects, 41 and 54 were aged ≤12 and > 12 months, among whom true pathogenic bacteria were identified in 12 (29.3%) and 19 (35.2%), respectively. The median TTP for the younger group with pathogenic bacteria was 11.2 (interquartile range, 10.0-11.9) hours, which was significantly shorter than that for the older group (12.6 [interquartile range, 11.9-16.9] hours) (P = 0.01). At 12 h after the initiation of culture, the younger group with pathogenic bacteria had a significantly higher positivity rate (83.3%) than the older group (26.3%) (P < 0.01). The times required for the positivity to exceed 90% were 13.4 and 20.1 h for the younger and older pathogenic groups and 30.4 and 67.8 h for the younger and older contaminant groups, respectively. The range of TTP could be assessed more accurately by considering the effect of age on the infectious background.
