The Role of Sensor-Activated Faucets in Surgical Handwashing Environment as a Reservoir of Legionella

Surgical handwashing is a mandatory practice to protect both surgeons and patients in order to control Healthcare-Associated Infections (HAIs). The study is focused on Legionella and Pseudomonas aeruginosa contamination in Surgical Handwashing Outlets (SHWOs) provided by sensor-activated faucets with Thermostatic Mixer Valves (TMVs), as correlated to temperature, technologies, and disinfection used. Samples were analyzed by standard culture techniques, comparing hot- and cold-water samples. Legionella isolates were typed by an agglutination test and by mip sequencing. Legionella contamination showed the same distribution between hot and cold samples concerning positive samples and mean concentration: 44.5% and 1.94 Log(10) cfu/L vs. 42.6% and 1.81 Log(10) cfu/L, respectively. Regarding the distribution of isolates (Legionella pneumophila vs. Legionella non-pneumophila species), significant differences were found between hot- and cold-positive samples. The contamination found in relation to ranges of temperature showed the main positive samples (47.1%) between 45.1–49.6 °C, corresponding to high Legionella concentrations (2.17 Log(10) cfu/L). In contrast, an increase of temperature (>49.6 °C) led to a decrease in positive samples (23.2%) and mean concentration (1.64 Log(10) cfu/L). A low level of Pseudomonas aeruginosa was found. For SHWOs located in critical areas, lack of consideration of technologies used and uncorrected disinfection protocols may lead to the development of a high-risk environment for both patients and surgeons.