Significance of Pseudomonas aeruginosa in sputum.

Pseudomonas aeruginosa was isolated from the sputum of 63 patients. In 34 the organism was a commensal, in 14 it was causing chronic suppuration, and in 10 had interfered with antibiotics directed against other organisms and was thus indirectly pathogenic. In five patients, all of whom died, the organism could have been acting as an acute pathogen. Attempts should be made to determine the nature of the organism's pathogenicity in a given patient and appropriate therapy withheld or administered accordingly.