Objective To investigate the contamination status of dental unit waterlines (DUWLs) in Shanghai hospitals, and to provide data support for public health intervention.
Methods A total of 2 330 water samples were collected on site from DUWLs in 189 hospitals with dental practice license from August to November 2014 to detect total bacteria counts, Pseudomonas aeruginosa, and Legionella. Basic information were collected by questionnaire and the risk factors of contamination of DUWLs were analyzed.
Results The qualification rates of source water, storage tank water, gargle water, oral washing water, and dental hand-piece water were 84.1% (318/378), 53.7% (151/281), 69.5% (387/557), 67.9% (378/557), and 53.1% (296/557), respectively. Three strains of Pseudomonas aeruginosa and six strains of Legionella were detected. The qualification rates of source water by supply of independent source water, filtered tap water, homemade distilled water, and others were 84.6% (22/26), 74.8% (77/103), 100.0% (3/3), and 98.4% (61/62), respectively. The qualification rates of non-purified, filter-membrane treated, and chemically disinfected water samples were 64.1% (1 356/2 115), 76.7% (23/30), and 81.6% (151/185), respectively. The qualification rate of dental hand-piece placed hanging 58.7% (212/361) was higher than that inclining 42.9% (84/196).
Conclusion DUWLs contamination is common in Shanghai hospitals. Quality control of source water should be strengthened and DUWLs should be disinfected promptly and effectively.
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