Pseudomonas aeruginosa is the most frequently isolated bacterium among those gram negative rods that are obligate aerobes (non-fermenters). It is a major cause of nosocomial infections where the source is often contaminated IV fluids, ophthalmic solutions, hydrotherapy tanks, respiratory equipment and even disinfectant solutions such as quaternary ammonium compounds. In the absence of strict hand washing protocols, this organism may be spread from patient to patient by the hands of hospital personnel. Organisms that have colonized the host to become part of the microbiota of the respiratory and gastrointestinal tract are another important source of infection. Five - 10% of healthy individuals may carry Pseudomonas aeruginosa in their gastrointestinal tract, but that percent increases among hospitalized patients because of the selective pressure of antibiotics. I