Follicular dermatitis outbreak caused by Pseudomonas aeruginosa associated with a motel's indoor swimming pool.

Fourteen cases of pustular dermatitis occurred in members of a snowmobile club who swam in a motel pool in West Yellowstone, Mont., in February 1978. Survey questionnaires identified seven additional cases in guests at the motel the same weekend. All those with rashes had used the swimming pool and dry sauna on February 17 or 18. Among 56 survey respondents, swimming pool and sauna use were significantly associated with illness (P = .0002 by Fisher's exact test). Pseudomonas aeruginosa serotype 0:11 was isolated from a pustule on the skin of one club member and from four samples of the indoor-outdoor carpet that surrounds the pool. A specific precipitating event for the outbreak was not identified, but disinfection practices at this facility (a single daily chlorination, no measurement of chlorine levels, toleration of grossly cloudy water, soggy poolside carpet) may have established conditions in which P. aeruginosa could grow intermittently and cause disease. These cases are the first documented outbreak of P. aeruginosa dermatitis in which a whirlpool bath has not been implicated.