An outbreak of otitis externa in competitive swimmers due to Pseudomonas aeruginosa.

Pseudomonas aeruginosa was isolated from the ears of 18 of the 25 members of a team of competitive swimmers who complained of painful discharging ears. This group of swimmers trained twice daily in the pool, in the early morning and late afternoon. In contrast swabbing of the ears of a similar group of 54 competitive swimmers who used the pool only in the afternoon revealed only one swimmer with P. aeruginosa. Investigation of the swimming pool revealed that chlorination was often inadequate when the first group of swimmers were training in the early morning. Strains of P. aeruginosa were isolated from various sites around the pool and from the bag of a vacuum used to clean the pool. Pyocin typing, serotyping and phage typing were performed on all isolates. The dominant strain recovered from the swimmers' ears was found to be almost identical to that from the vacuum bag and belonged to serotype 0--11 which has been particularly associated with outbreaks of P. aeruginosa infection in whirlpools in the United States. These results support the hypothesis that there is a direct correlation between the development of otitis externa and swimming in water contaminated with P. aeruginosa.