Intracellular Pseudomonas aeruginosa: internalization and survival.

Pseudomonas aeruginosa is an opportunistic human pathogen that can colonize multiple tissues and establish chronic infections with a high rate of relapse. P. aeruginosa survives intracellularly in multiple cell types, including in biopsies from human patients. Intracellular bacteria are partially protected from the immune system, from antibiotics with poor penetration across eukaryotic membranes, and, in some cases, also from antibiotics that penetrate eukaryotic membranes, such as fluoroquinolones. This suggests that P. aeruginosa can establish an intracellular reservoir that may contribute to chronic infection and relapse. However, the intracellular life cycle of P. aeruginosa is poorly understood. In this review, we summarize the ways in which P. aeruginosa interacts with eukaryotic cells and the role of its protein secretion machineries in establishing an intracellular niche.