OBJECTIVE: To assess and synthesize available evidence in the infection control and healthcare design literature on strategies using the built environment to reduce the transmission of pathogens in the air that cause healthcare-associated infections (HAIs).BACKGROUND: Air can serve as a route for transmission of important HAI pathogens, including Mycobacterium tuberculosis and influenza, and may play a role for others typically transmitted by contact, including Staphylococcus aureus and Clostridium difficile.TOPICAL HEADINGS: Four primary interventions can be used interrupt the transmission of pathogens in air: ventilation, filtration, decontamination, and isolation. Many studies demonstrate that unidirectional airflows, when combined with very clean air and frequent air changes, reduce bacterial counts in the air, though mostly focused on the operating room. A high-efficiency particulate air filter removes almost all particles from the air and is used in protective environments such as the operating room, but little evidence supports its broader application. Ultraviolet germicidal radiation can augment the performance of heating, ventilation, and air conditioning systems. Isolation with negative pressure ventilation prevents spread of airborne pathogens such as tuberculosis.CONCLUSIONS: Current evidence is limited by the complexity of the interactions between pathogens and potential hosts, and in the methods used to assess impact of these strategies. Because the factors that affect transmission of the pathogens are complex and transcend disciplines, a collaborative approach among the key stakeholders in healthcare facility design should be actively pursued from planning to completion of construction and in rigorous research to best determine how design can reduce HAIs.

To assess and synthesize available evidence in the infection control and healthcare design literature on strategies using the built environment to reduce the transmission of pathogens in water that cause healthcare-associated infections (HAIs). BACKGROUND: Water can serve as a reservoir or source for pathogens, which can lead to the transmission of healthcare-associated infections (HAIs). Water systems harboring pathogens, such as Legionella and Pseudomonas spp., can also foster the growth of persistent biofilms, presenting a great health risk. TOPICAL HEADINGS: Strategies for interrupting the chain of transmission through the built environment can be proactive or reactive, and include three primary approaches: safe plumbing practices (maintaining optimal water temperature and pressure; eliminating dead ends), decon-tamination of water sources (inactivating or killing pathogens to prevent contamination), and selecting appropriate design elements (fixtures and materials that minimize the potential for contamination). CONCLUSIONS: Current evidence clearly identifying the environment's role in the chain of infection is limited by the variance in surveillance strategies and in the methods used to assess impact of these strategies. In order to optimize the built environment to serve as a tool for mitigating infection risk from waterborne pathogens-from selecting appropriate water features to maintaining the water system-multidisciplinary collaboration and planning is essential.

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This article describes the role of the hospital environment in the spread of pathogens by direct and indirect contact. In addition, the prevention of transmission through interventions involving the built environment is discussed. BACKGROUND: The hospital environment can become contaminated with pathogenic microorganisms, some of which can persist for long periods of time. Although contamination is common, the contribution of the hospital environment to the development of healthcare-associated infections remains unclear. In part spurred by the development of newer technologies to enhance environmental cleaning or to prevent contamination, research into the role of the environment in causing healthcareassociated infections has accelerated. TOPICAL HEADINGS: A review of the recent literature finds an increasing body of evidence implicating contaminated surfaces in patient care areas in the transmission of pathogens and the development of infections. Single-patient rooms and optimally placed alcohol hand rub dispensers and other design features can mitigate infection risk. Enhanced environmental cleaning including touchless technologies and self-cleaning surfaces can reduce environmental contamination and may prevent infections. CONCLUSIONS: The hospital environment contributes to transmission of pathogens in hospitals and to the development of healthcare-associated infections. Newer technologies to prevent environmental contamination or to enhance cleaning are promising although additional studies with the endpoints of reduction of infections are needed before the role of these technologies is known.

To describe the conceptual framework and methodology used to conduct a comprehensive literature review of current evidence evaluating the role of the built environment in the transmission of healthcare-associated infections. BACKGROUND: A multidisciplinary approach to evaluating a vast and diverse dataset requires a conceptual framework to create a common understanding for interpretation. This common understanding is accomplished through the application of a "chain of transmission" model, depicting temporal and physical paths of pathogens that cause healthcare-associated infections. The chain of transmission interventions model argues that infection can potentially be reduced by interrupting any of several links in the chain. TOPICAL HEADINGS: The key pathogens impacted by the built environment are identified. The chain of transmission and the conceptual framework are described. Opportunities for intervention through the built environment are presented, which in turn guide the subsequent methodology used to conduct the systematic literature review. CONCLUSIONS: The chain of transmission interventions model is a multidisciplinary conceptualization of the interaction between pathogens and the built environment, and this model facilitated a systematic literature review of a very large amount of data.