The Legionella contamination of tap water in a brand-new hospital in Japan before patients move in

To the Editor—Healthcare facilities are potential settings for Legionella infections, and 2%–20% of Legionnaires’ disease cases have been estimated to have been acquired at hospitals, long-term care facilities, and clinics.^1,2 The widespread contamination of Legionella spp in the water systems of healthcare facilities has recently been recognized.^3,4 The persistent environmental contamination of Legionella spp in water systems can often be difficult to eradicate once the organism colonizes because the organism is likely to continue to survive in dead branches of complex plumbing systems. Furthermore, identifying the sources of Legionella spp contamination in hospital water systems and determining when colonization occurred can be difficult. Because most studies are performed in operational hospitals, the identified relationships between hospital water systems and Legionella are often attributed to old, scaled water pipes.

We evaluated the environmental contamination of Legionella spp before patients moved into a brand-new hospital, which was built by a leading Japanese construction company. The study was conducted in June 2019 at Tokyo Medical University Hospital, a 19-story building that has 905 beds and a 3-story basement (completed in March 2019). Overall, 61 sampling points were selected, including 27 manual faucets, 18 touch-free faucets, and 16 showers in inpatient hospital wards. A hot water sample and a cool water sample were obtained at each sampling point. In total, 122 500-mL samples were obtained, starting as soon as the water began to flow, and samples were stored in sterilized bottles. All samples were concentrated on a filtration, followed by treatment at 50°C for 30 minutes. These samples were cultured using Wadowsky-Yee-Okuda-α-ketoglutarate agar culture medium (Eiken Chemical, Tokyo, Japan). Cultures were incubated in a humid environment for 5 days at 36 ± 1°C.

Among the 122 samples taken, 1 sample, from the highest floor, was positive for Legionella spp. Matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry was used to identify the specimen, resulting in a score of 1.77 for L. felleii. No reaction during the serological aggregation test (Denka Seiken, Tokyo) was observed against L. pneumophila serogroup (SG) 1-SG6, L. bozemanii, L. dumoffii, Legionella gormanii, or L. micdadei.

This study is the first report to describe the Legionella contamination of water taps in a brand-new building, before the start of standard usage. Water taps, showers, sinks, and water systems in healthcare facilities have been recognized to be the causes of healthcare-associated legionellosis.^3–5 Previous studies have not considered the possibility that even brand-new hospital water systems may be at risk for Legionella spp colonization during the building process, which can persist and spread once the hospital is operational. Although Legionella spp contamination in water systems has been associated with water scale, stagnant water, and sediment, brand-new buildings, even prior to active use, may possess contamination risk factors, such as stagnant dead spaces.³ This study indicates that we must pay attention to the risks of healthcare-associated waterborne infections, even in brand-new buildings and before patients move in.