Methicillin-resistant Staphylococcus aureus contamination of hospital-use-only mobile phones and efficacy of 222-nm ultraviolet disinfection.

Kaiki, Yuki; Kitagawa, Hiroki; Hara, Toshinori; Nomura, Toshihito; Omori, Keitaro; Shigemoto, Norifumi; Takahasahi, Shinya; Ohge, Hiroki

BACKGROUND Mobile phones may be contaminated with nosocomial pathogens such as methicillin-resistant Staphylococcus aureus (MRSA). The aim of this study was to investigate the MRSA contamination rate on doctors' hospital-use-only mobile phones and the efficacy of 222-nm ultraviolet light (UV) disinfection. METHODS We investigated the MRSA contamination rate of doctors' hospital-use-only mobile phones, as well as the reduction in MRSA counts on plastic plates and aerobic bacteria (AB) on mobile phones before and after exposure to 222-nm UV irradiation. RESULTS Five (10%) of the 50 mobile phones investigated were contaminated with MRSA. Exposure to 0.1 mJ/cm2 222-nm UVC irradiation for 1.5 and 2.5 min (9 and 15 mJ/cm2) achieved mean log10 MRSA colony-forming units (CFU) reductions of 2.91 and 3.95, respectively. Exposure to 9 mJ/cm2 222-nm UVC irradiation (0.1 mW/cm2 for 1.5 min) significantly reduced AB contamination on mobile phones (P < 0.001). CONCLUSIONS The use of 222-nm UV disinfection resulted in effective in vitro reduction of MRSA and significantly reduced AB contamination of mobile phone surfaces.