Sanitizing surfaces is part of nosocomial infection in health care environments. Modern sanitizing methods such as Non-flammable Alcohol Vapor in Carbon Dioxide systems have been effective against gastroenteritis, methicillin-resistant "Staphylococcus aureus", and influenza agents. Use of hydrogen peroxide vapor has been clinically proven to reduce infection rates and risk of acquisition. Hydrogen peroxide is effective against endospore-forming bacteria, such as "Clostridium difficile", where alcohol has been shown to be ineffective. Ultraviolet cleaning devices may also be used to disinfect the rooms of patients infected with "Clostridium difficile" or methicillin-resistant "Staphylococcus aureus" after discharge.