NE stimulates pneumococcal growth and biofilm formation. Panels A- E show the time course of growth of wildtype S. pneumoniae strain D39, TIGR4, and passaged D39 (D39-p) in serum-medium with (red line) and without (black line) the addition of 10 μM NE, epinephrine or dopamine. Panel F is a microscope image showing how NE increased clumping (cell-cell association) of D39 relative to the control, and also increased viability (shown by reduction in cellular lysis debris). Panel G shows the initial attachment of wildtype D39 after 24, 48 and 72 hrs incubation in serum-medium +/-10 μM NE. Attachment was measured as described in Materials and Methods; key: black bar (control); grey bar (NE); P < 0.05 for the collective values of all the NE vs. Control data points. Similar results were also seen with TIGR4 (data not shown). For all experiments, n = 3.