P. aeruginosa is widely distributed in nature and in the hospital environment with a predilection for moist areas. Its inherent resistance to many antimicrobials and its ability to produce many enzymes contribute to its pathogenic potential as both a primary and a secondary cause of infection. It is easily grown and identified in the microbiology laboratory. However, susceptibility testing remains a problem. Currently, the best approach to treatment is an aminoglycoside and an antipseudomonal beta-lactam antimicrobial. Typing can differentiate strains, but should be reserved for specific epidemiologic problems.