Pseudomonas Aeruginosa—Contaminant or Pathogen?

When Pseudomonas aeruginosa is cultured from the blood or from the sputum in sufficient number, there is seldom any hesitancy in attributing the concurrent septicemia or pneumonia to this organism. In those areas accessible to air-borne contaminants, it has been accepted as the causative agent in certain cases of external otitis and in paronychial infection accompanied by blue-black nails 1 (Fig. 1) and as a secondary invader of burns. Paradoxically, it is almost never accepted as a pathogen in other lesions of skin from which it is cultured. The occurrence of skin lesions from which Pseudomonas can be cultured during the course of Pseudomonas septicemia lends credence to the belief that this organism may be a pathogen in glabrous skin. This occurrence is well documented by Forkner, Frei, Edgcomb, and Utz, 2 who classify the skin lesions occurring during Pseudomonas septicemia as follows: Ecthyma gangrenosa. These were round, indurated, ulcerated areas with