G-CSF during Escherichia coli versus Staphylococcus aureus Pneumonia in Rats Has Fundamentally Different and Opposite Effects

We investigated if bacteria type alters outcome with prophylactic granulocyte colony stimulating factor (G-CSF) therapy during pneumonia. Rats received G-CSF or placebo daily for 6 d and after the third dose were intrabronchially inoculated with either Escherichia coli or Staphylococcus aureus. Without G-CSF, E. coli and S. aureus produced similar (p = NS) mortality rates (36 versus 38%) and serial changes in mean circulating neutrophil counts (CNC), but differing mean ( ± SE) tumor necrosis factor (TNF) levels (E. coli, 259 ± 104 versus S. aureus, 51 ± 17 pg/ml, p = 0.01). G-CSF prior to bacteria increased mean CNC more than six times compared with placebo (p = 0.001). However, with G-CSF in the first 6 h after E. coli, there was a greater than 20-fold decrease in mean ( ± SE) CNC ( × 103/ mm3) to below placebo (0.5 ± 0.1 versus 0.8 ± 0.1), whereas with G-CSF after S. aureus, there was only a fivefold decrease in mean CNC and CNC were greater than placebo (1.8 ± 0.2 versus 0.8 ± 0.1) (E. coli versus S. a...