Fig. 1.

Histopathology of acute Pseudomonas aeruginosa strain PAO1 infection. The lungs of noninfected weanling (A) and adult (C) strain Fischer 344 (F344) rats were essentially normal with thin alveolar septa and no infiltrates. Interstitial pneumonitis with diffuse widening of alveolar septa due to lymphomononuclear infiltrates was noted in weanlings after 5 days of PAO1 infection (B). The lungs of infected adult rats (D) were almost normal at 5 days, although there was a mild widening of the alveolar septa due to sparse lymphocytic infiltrate. n = 3 rats per group.