FIG 3.

Bacterial population doubling in whole blood. Pairs of Alab49WT and/or isogenic mutant strains were rotated in whole human blood for 3 h (bactericidal assay), and the increase in bacterial population size relative to the inoculum size was measured. The mean average value for the log₂ increase in CFU is indicated for each sample group (bar); a net loss of CFU was given a score of zero. Paired t test (two-tailed) values for differences in the number of bacterial population doublings are shown as follows: **, t < 0.01. Differences in inoculum doses were not statistically significant between bacterial pairs (two-tailed paired t test) (data not shown); each set of comparisons (A to F) employed 2 to 4 different blood donors. The difference between groups in panel F (ΔfbaA versus ΔfbaAΔpam) is also highly significant (two-tailed paired t test); however, the sample size is smaller than the minimum (i.e., 5 pairs) that is recommended for implementing this statistical test.