Concentrations of the Pseudomonas aeruginosa toxin pyocyanin in human ear secretions.

Pseudomonas aeruginosa is the most common bacterium in chronic otitis media. Several extracellular factors have been described. Pyocyanin (Pyo) is the blue pigment that gives the bacterium its name "the pyocyanous bacteria". Pyo is known to have an inhibitory effect on the activity of cilia. It is a zwitterion that might easily penetrate biological membranes. Samples of ear secretions for culture and analysis of the concentration of Pyo were collected from 17 patients with different ear infections. Concentrations varied from 3 to 2714 nmol/g, with a mean of 905 nmol/g. For comparison, concentrations were also measured in bacteriological filtrates of P. aeruginosa obtained from wounds and urine specimens. Concentrations in filtrates varied from 13 to 8114 nmol/g, mean 1968 nmol/g. The results indicate that pyocyanin might act as virulence factor that compromises ciliary function and enables the microorganism to establish itself within the ear.