Bacterial load is independent of inoculum density. Groups of 7-16 five-day-old neonatal rats were inoculated with 102-108 cfu of either S. pneumoniae, H. influenzae or S. aureus. The 25th to 75th percentiles of nasal wash and epithelium samples taken 48 hours after bacterial challenge are represented by the box plots, with the bold horizontal bar indicating the median value, circles outlying values and dotted error bars SE. P values were determined by Kruskal-Wallis rank sum which tested the null hypothesis that the bacterial load are distributed the same in all of the inoculum groups. Dashed line represents limit of detection.