Otitis externa due to Pseudomonas in swimming pool bathers.

An outbreak of otitis externa was observed to affect one third of 230 swimmers using a new swimming pool within three weeks of its opening. Pseudomonas aeruginosa was grown from the water and from all of the nine swabs taken from the infected ears of the swimmers. During the same period only six other cases of otitis externa were seen in the local general practice serving 4,000 patients. The disinfection procedures were found to be defective and after they were corrected the outbreak subsided.