Figure 2. Model of the different phases of Pseudomonas aeruginosa infection. After an initial colonization phase, mostly dependent on cell-associated virulence factors, the infectious process evolves either to a chronic infection characterized by low production of extracellular virulence factors or to an acute infection characterized by high production of cell-to-cell signaling dependent virulence factors. During acute exacerbation of chronic infection, the production of cell-to-cell signaling dependent virulence factors is highly increased.