Pseudomonas aeruginosa infections in the intensive care unit

Pseudomonas aeruginosa is a common and highly lethal agent of nosocomial infection, especially among intensive care unit patients. It is widespread in the environment and commonly recovered from water in nature and in hospital settings. P aeruginosa is endowed with a formidable array of virulence factors that facilitate attachment to host cells, tissue invasion, and systemic disease. It is intrinsically resistant to many commonly employed antibiotics due to a complex variety of mechanisms briefly reviewed here. Resistance to fluoroquinolones appears to be increasing particularly rapidly. Recent advances in the understanding of the molecular biology of this organism have shed considerable light on its ability to form biofilms, which facilitate adherence, especially in cystic fibrosis patients, and confer resistance to clearance by host immune mechanisms and antimicrobial killing. Treatment studies have demonstrated a significant risk of emergence of resistance during therapy with a variety of agents. Several studies suggest that two drugs are better than one for therapy of serious infections, although dual therapy does not always prevent emergence of resistant strains. The sequencing of the genome will lead to new understanding of pathogenesis and may identify new drug targets.