Fig. 1.

Typical time course of P. aeruginosa colonization of the CF respiratory tract. Initial acquisition of a wild-type environmental isolate of P. aeruginosa is treated with antibiotics and eradicated. During subsequent intermittent infections, genetic adaptations to the CF airway result in impaired bacterial clearance. These adaptations include: a transition to a biofilm mode of growth, production of a mucoid coating to elude phagocytosis, altered expression of virulence factors like flagellin and LPS, and enhanced resistance to antibiotics. Eventually a dominant genotypic clone emerges, which continues to adapt to its host.