Effect of a UV-C Automatic Last-Generation Mobile Robotic System on Multi-Drug Resistant Pathogens

Abstract

Background: Healthcare-associated infections caused by multi-drug resistant (MDR) pathogens are associated with increased mortality and morbidity among hospitalized patients. Inanimate surfaces, and in particular high-touch surfaces, have often been described as the source for outbreaks of nosocomial infections. The present work aimed to evaluate the efficacy of a last-generation mobile (robotic) irradiation UV-C light device R2S on MDR microorganisms in inanimate surfaces and its translation to hospital disinfection.

Methods: The efficacy of R2S system was evaluated in environmental high-touch surfaces of two separate outpatient rooms of Perugia Hospital in Italy. The static UV-C irradiation effect was investigated on both the bacterial growth of S. aureus, MRSA, P. aeruginosa, and K. pneumoniae KPC and photoreactivation. The antimicrobial activity was also tested on different surfaces, including glass, steel, and plastic.

Results: In the environmental tests, the R2S system decreased the number of bacteria, molds, and yeasts of each high-touch spot surface (HTSs) compared with manual sanitization. UV-C light irradiation significantly inhibits in vitro bacterial growth, also preventing photoreactivation. UV-C light bactericidal activity on MDR microorganisms is affected by the type of materials of inanimate surfaces.

Conclusions: The last-generation mobile R2S system is a more reliable sanitizing procedure compared with its manual counterpart.

Keywords: MDR microorganisms; UV-C light device; disinfection; high-touch surface; photoreactivation.

Figure 1

Workflow of the R2S system. R2S robot is equipped with a dedicated app able to read a QR code in which the mission is memorized (all the steps and the time of irradiation of each stop point).

Figure 2

R2S mission performed in two different outpatient rooms (Room 1 and 2) of the “Santa Maria della Misericordia” Hospital in Perugia and the schematic representation of the sampling spots. The test was carried out in the two rooms following the indicated steps. Outpatient rooms 1: the distances measured between the UV-C light device R2S irradiation step 1 and the sampling point of surfaces, such as internal door handle (1), floor (2), the right arm of the patient chair (3), and computer keyboard and mouse (5), which were 28, 45, 62, and 50 cm, respectively. The distance between R2S irradiation step 2 and the sampling spot on the bench (4) was 30 cm. Outpatient rooms 2: the distances measured between the UV-C light device R2S irradiation step 1 and the sampling point of surfaces, such as internal door handle (1) and the right armrest of the patient’s chair (2), which were 25 and 50 cm, respectively. The distances between R2S irradiation step 2 and the sampling points on the sink (3) and floor (4) were 38 and 40 cm, respectively. The distance between R2S irradiation step 3 and the sampling point on the bench (5) was 30 cm.

Figure 3

Outpatient room disinfection with the UV-C robotic systems R2S compared to standardized manual protocol based on chlorine solution nebulization. Mean ± SD data were calculated from the two determinations described in Materials and Methods. The CFU number of bacteria, yeast, and molds was assessed as described in the Materials and Methods section. Black bars: CFU before sanification; gray bars: after manual disinfection; white bars: after R2S disinfection.