Pseudomonas aeruginosa previously has been reviewed in “Topics in Clinical Microbiology.” However, the increased importance of this micro-organism in nosocomial infections as well as new information on pathogenic mechanisms is such that this topic should be “revisited.” For example, the ubiquitous presence of this bacterium in nature and its ability to survive in hostile environments has been recently emphasized by episodes of P aeruginosa peritonitis, bacteremia and pseudobacteremia that have been linked to contaminated povidone-iodine. Clearly, P aeruginosa is an important pathogen and is deserving of careful and deliberate consideration.
The role of P aeruginosa as a nosocomial pathogen in hospitalized patients with critical illness is rapidly increasing. Recent data from the Centers for Disease Control (CDC) have shown that while nosocomial infections from Escherichia coli and Klebsiella have remained relatively constant from 1975 to 1984, the proportion of such infections caused by Pseudomonas has risen from 6.3% in 1975 to 11.4% in 1984. The frightening aspect of this epidemiologic data is the extremely high rate of mortality associated with hospital-acquired Pseudomonas infections. For example, the mortality rate for Pseudomonas bacteremia often ranges from 67% to 90% for neutropenic cancer patients. Among more general hospital patient populations, the mortality rate for Pseudomonas bacteremia can be similar depending on the underlying condition of the host.