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

**Marta Mazzotta 1, Luna Girolamini 1, Maria Rosaria Pascale 1, Jessica Lizzadro 1, Silvano Salaris 1, Ada Dormi 2 and Sandra Cristino 1,\***


Received: 3 May 2020; Accepted: 3 June 2020; Published: 5 June 2020

**Abstract:** 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 Log10 cfu/L vs. 42.6% and 1.81 Log10 cfu/L, respectively. Regarding the distribution of isolates (*Legionella pneumophila* vs. *Legionella* non-*pneumophila* species), significant di fferences 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 Log10 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 Log10 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.

**Keywords:** Healthcare-Associated Infections (HAIs); Surgical Handwashing Outlets (SHWOs); sensor-activated faucets; *Legionella* spp.; risk assessment plan
