Outbreak of severe Pseudomonas aeruginosa infections caused by a contaminated drain in a whirlpool bathtub

During a 14-month period, 7 patients with hematological malignancies acquir ed serious infections caused by a single strain of multiply resistant Pseud omonas aeruginosa. A case-control study, culture surveys, and pulsed-field gel electrophoresis implicated a whirlpool bathtub on the unit as the reser voir. All case patients and 32% of control patients used this bathtub P=.00 3). The epidemic strain was found only in cultures of samples taken from P =. 003 the bathtub. The drain of the whirlpool bathtub, which was contamina ted with the epidemic strain, closed similar to2.54 cm below the drain's st rainer. Water from the faucet, which was not contaminated, became contamina ted with P. aeruginosa from the drain when the tub was filled. The design o f the drain allowed the epidemic strain to be transmitted to immunocompromi sed patients who used the whirlpool bathtub. Such tubs are used in many hos pitals, and they may be an unrecognized source of nosocomial infections. Th is potential source of infection could be eliminated by using whirlpool bat htubs with drains that seal at the top.