Figure 3.

Adherence of S. pneumoniae serotypes 3, 19A and 19F to polystyrene wells. Late attachment of serotype 3 and serotypes 19A and 19F S. pneumoniae isolates was measured by (A) staining adhered cells with crystal violet to measure differences in biofilm biomass after 4 h incubations or by (B) quantifying the CFUs that remained attached to 24-well polystyrene plates and the CFUs that were recovered in THY wash after 4 h incubations. Percentage of total bacteria adhered was determined by dividing attached CFUs by total CFUs. Each sample used in both assays was tested in duplicate wells and all assays were repeated at least once. Bars represent the group means + SEM of samples from all assays. Statistical analysis was performed using a two-tailed Student's t-test. Comparisons are vs. WU2. (A single asterisk denotes P ≤ 0.05, double asterisks denote P ≤ 0.01 and triple asterisks denote P ≤ 0.001).