Pseudomonas aeruginosa is a gram-negative, oxidase-positive, motile rod, which frequently grows on agar in yellow-green iridescent colonies resulting from two pigments, pyocyanin and fluorescein, diffused in the medium.

Pseudomonas can be found occasionally in the axilla and anogenital areas of normal skin but rarely in the stools of adults unless antibiotics are given. The organism is commonly a contaminant of lesions populated with more virulent organisms but occasionally it causes infection...