Environmental Interventions to Control Nosocomial Infections

Many epidemics of nosocomial infections have stemmed from reservoirs of pathogens in the inanimate hospital environment.1 However, the contribution of the environment to the acquisition and spread of endemic nosocomial infections has been thought to be insignificant.2,3 In this issue, Timothy E. Cooney provides experimental data on the efficacy of copper-based paints to reduce surface contamination.4 Heavy metals have been used in clinical medicine for more than 100 years as microbicides. The use of heavy-metal-containing compounds has included topical silver nitrate to prevent ophthalmia neonatorum, topical silver sulfadiazine to treat burn wounds, and copper-8-quinolinolate to reduce fungal growth above false ceilings. More recently, heavy metals such as silver have been bonded to Foley and intravenous catheters in an attempt to reduce the incidence of urinary tract infections or intravascular line-associated bacteremia. Factors that may limit increasing use of heavy metals include concerns about toxicity and the ability of microorganisms to develop resistance to heavy metals; such resistance may be transferred on plasmids.5 Several criteria should be met prior to instituting an intervention to control environmental contamination of painted surfaces such as walls. First, has the environmental surface been shown to be a reservoir of nosocomial pathogens? Second, has this reservoir been linked to endemic or epidemic nosocomial infections? Third, can environmental manipulation reduce or eliminate nosocomial pathogens on this reservoir? Fourth, can the elimination of the reservoir be shown scientifically to reduce endemic or epidemic infections? Finally, assuming all of the above have been demonstrated, what is the most efficient method of eliminating the environmental source or reservoir? Scientific studies of Legionella and Aspergillus have fulfilled the above criteria for demonstrating an environmental reservoir and have led to guidelines for control of the environmental source.6 Guidelines regarding the maintenance of the hospital ventilation system and containment of dust associated with hospital renovations have been successful in preventing Aspergillus infections in immunocompromised patients. Similarly, the elucidation of the water reservoirs of Legionella has led to guidelines on methods to eliminate Legionella reservoirs when epidemiologically linked to hospital-acquired infections. The present study compares the bactericidal activity of several copper and noncopper paints in a laboratory setting. It appears that copper paints, when applied to glass coverslips, were able to achieve a 5-log to 7-log reduction of test organisms within 24 hours. The data also demonstrated that a standard latex interior paint with a microbicidal additive achieved mean reductions in test organisms of 5 logs in 24 hours and greater than 6 logs in 48 hours. How should the data provided by Cooney be evaluated and applied? Several scientific issues bear on whether copper-based paints should be incorporated into routine infection control practices. First, a review of the literature fails to demonstrate that walls