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P. aeruginosa outbreak in NICU linked to contaminated tap water
An outbreak of Pseudomonas aeruginosa in a hospital neonatal ICU in the fall of 2013 has been traced to contaminated hospital tap water by CDC investigators, according to findings published in Infection Control & Hospital Epidemiology.
“Multiple P. aeruginosa outbreaks have been documented in NICUs and have been attributed to contaminated medications, respiratory equipment, laryngoscopes and personnel hand contamination,” Cara Bicking Kinsey, PhD, from the division of scientific education and professional development at the CDC, and colleagues wrote. “[Outbreaks] have also been associated with contaminated hospital tap water because the organism is hardy and can form biofilms in plumbing fixtures that resist chemical treatment.”
Following reports of a P. aeruginosa outbreak involving 15 patients and two deaths in a 28-bed NICU, CDC investigators conducted an infection control assessment, an environmental evaluation and a case-control study that included all neonatal patients seen in the hospital between June 1, 2013 and Sept. 30, 2014.
Kinsey and colleagues evaluated infection control observations, interviews and environmental assessments, and later, the risk factors for infection were determined through a matched case-control study. They also observed the connections between strains by using pulse-field gel electrophoresis on samples collected from patients and environmental isolates.
According to investigators, P. aeruginosa infection was identified in 31 patients. Case clusters were temporally linked with the absence of point-of-use filters on faucets in patient rooms; after adjusting for gestational age, researchers found that infected patients were more likely to have occupied a room without a point-of-use filter (OR, 37.55; 95% CI 7.16-∞).
Additionally, these patients had higher odds of exposure to peripherally inserted central catheters (OR, 7.20; 95% CI, 1.75-37.30) and invasive ventilation (OR, 5.79; 95% CI, 1.39–30.62).
Following testing, the researchers determined that the majority of environmental samples (n = 28; 67%) taken from the NICU grew P. aeruginosa bacteria. The differences between the most recent two case patient isolates and water-related samples collected from the rooms were indistinguishable.
“Our findings are consistent with the statement made by Williams et al that waterborne health care-associated infections occur ‘at the three-way intersection of nonsterile potable water, susceptible individuals and a lapse in infection control practices.’ All three factors likely contributed to this outbreak.” Kinsey and colleagues wrote. “This outbreak highlights the importance of addressing and understanding the inherent risks in health care facilities where water has been stagnant for extended periods.”
Disclosure: The researchers reported no relevant financial disclosures.
Perspective
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From a water industry perspective, this study highlights a very timely issue that water utilities are facing throughout the United States. Typically, when discussing waterborne disease and pathogens, the focus has been on examining surface water quality before it enters a plant and, even more importantly, examining water as it leaves a plant to assess the effectiveness of water treatment. However, with the ever-aging infrastructure of water distribution systems, compounded by the ability of certain organisms to grow in premise plumbing — connecting houses, hospitals, schools and their water systems — we are dealing with a whole new potential problem.
Premise plumbing is not routinely assessed and it is difficult to assess and control organisms that can grow in that environment. In a hospital setting, however, it sets up a perfect scenario for opportunistic pathogens to multiply in stagnant water and risk exposure to vulnerable, immunocompromised patients. Everyday consumers could face similar potential issues with their water distribution systems in their homes, which begs the questions whether physicians should be advising certain subpopulations — namely those who are immunocompromised including pregnant women and the elderly — to have some type of point-of-use device at their tap?
During the 1993 Cryptosporidium outbreak in Milwaukee, the largest documented outbreak in the U.S., deaths attributed to the disease were predominantly among immunocompromised groups, HIV patients and elderly individuals who had been drinking water straight from the tap that had typically met EPA standards. When one considers this type of extreme scenario, perhaps point-of-use devices should be considered and carefully regimented in the hospital setting to reduce the possibility of nosocomial infection.
