Pseudomonas aeruginosa is one of the most commonly considered gram-negative aerobic bacilli in the differential diagnosis of a number of probable gram-negative infections. This organism is frequently feared because it causes severe nosocomial infections, especially in immunocompromised hosts, and is often antibiotic resistant, complicating the choice of therapy.
P. aeruginosa is a non-fermentative gram-negative aerobic rod that grows easily on a variety of media. A characteristic sweet grape like odor, the elaboration of green pigment, and its oxidase-positive property are helpful in confirming its presence on culture plates. Occasionally, identification by laboratory personnel may be delayed because isolates lack pigments or produce unusual characteristics, such as a "rotten-potato" odor .
The clinical manifestations, diagnosis, and treatment of P. aeruginosa bacteremia and endocarditis will be reviewed here. The clinical manifestations and management of other P. aeruginosa infections and the epidemiology and pathogenesis of infection with this organism are discussed separately. (See related topics).
Epidemiology — P. aeruginosa infection is a nosocomial problem worldwide [2-7]. In a prospective analysis from the SCOPE (Surveillance and Control of Pathogens of Epidemiologic Importance) database of 24,179 nosocomial bloodstream infections occurring in 49 hospitals in the United States between 1995 to 2002, Pseudomonas species accounted for 4 percent of cases and were the third leading cause of gram-negative infections . (See "Epidemiology, pathogenesis, and microbiology of intravascular catheter infections".)
Risk factors for P. aeruginosa bacteremia include [4,7-13]: