Outbreak investigation of Pseudomonas aeruginosa infections in a neonatal intensive care unit

•Tap water use from contaminated hospital plumbing led to an outbreak of Pseudomonas aeruginosa infections.•Pseudomonas aeruginosa strains were found in patient, sink, and stored breast milk isolates.•Water-associated, health care–associated infections require a multidisciplinary approach. A Pseudomonas aeruginosa outbreak was investigated in a neonatal intensive care unit that had experienced a prior similar outbreak. The 8 cases identified included 2 deaths. An investigation found the cause of the outbreak: tap water from contaminated hospital plumbing which was used for humidifier reservoirs, neonatal bathing, and nutritional preparation. Our findings reinforce a recent Centers for Medicare & Medicaid Services memo recommending increased attention to water management to improve awareness, identification, mitigation, and prevention of water-associated, health care–associated infections.