Otitis due to Pseudomonas aeruginosa serotype 0:10 associated with a mobile redwood hot tub system--North Carolina.

From March 19 to April 2, 1982, six cases of Pseudomonas aeruginosa, serotype 0:10, in­ fection occurred following common exposure to a hot tub in Orange County, North Carolina. Clinical illness included severe hemorrhagic external otitis, which, although commonly asso­ ciated with swimming pools, has not been previously reported in the literature for whirlpool/spa settings. Among 24 members of a university coeducational fraternity who used the implicated tub from March 26 to 29, two had simple dermatitis, and four developed severe external otitis, one of whom, a 1 9-year-old male, had concurrent cellulitis of the chest wall and thigh. He was hos­ pitalized and treated with intravenous tobramycin for 4 days. His infection began as an area of erythema approximately 1-1/2 inches in diameter below the left nipple, accompanied by tender left axillary adenopathy and a pustule below the right nipple. The patient also noted severe pain and drainage from his left ear. Cultures from the chest pustule and the draining left ear were positive for P. aeruginosa serotype 0:10 (resistant to cephalothin, ampicillin, tetracycline, and trimethoprim-sulfamethoxazole and sensitive to gentamicin and carbenicillin). His symptoms began 48 hours after last exposure to the tub. The three other persons with severe external otitis that began within 48 hours of last exposure to the tub visited the student health service for treatment. In two of those, disease was bilateral and was associated with profound erythe­ ma or bloody discharge. The first had onset on March 27; the other, with onset on March 29, had a positive culture of ear drainage for P. aeruginosa of the same resistance pattern as the 19year-old male. Neither responded to topical antibiotics, but both were treated successfully with intramuscular gentamicin. A survey of fraternity members showed an association of illness with exposure to the tub, which was rented and used from March 26 to 29. Of 15 students who responded to a questionnaire, five (described above) met the case definition of ear infection or skin rash devel­ oping within 7 days after exposure to this tub. Total duration of exposure to the tub over the 4-day period was significantly associated with illness. Patients had a mean duration of 10.2 hours exposure; non-patients had a mean duration of 5.1 hours exposure (t = 2.83, p < 0.02). Only one of the five patients had exposure to another recreational water supply, spa, or whirlpool. The hot tub in question was a portable, self-contained unit constructed of redwood; it mea­ sured approximately 6 feet in diameter by 4 feet deep, and held 700 gallons. It was mounted on a trailer for easy transport and had terraced observation decks above and below. The tub was filled with city water, supplied through a garden hose. A recirculation system with a pump, hair trap, dual filter, continuous-feed brominating system, air-introduction port (for a bubbling effect), and propane-fueled heating system were built in. Water could be drained to surrounding