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TABLE 83-1 Airborne Microbial Contamination Associated with Construction—Selected Studies by Year and Microorganism | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Prevention of Infections Related to Construction, Renovation, and Demolition in Healthcare Facilities
Prevention of Infections Related to Construction, Renovation, and Demolition in Healthcare Facilities
Judene M. Bartley
Russell N. Olmsted
Construction, renovation, and remediation of the built environment are a constant process in healthcare facilities. The former aspect, new construction, may be infrequent in any single facility, but the latter are typically encountered in all settings as the use of the built environment is much higher compared to other business occupancies, and the unique nature of care delivery requires extraordinary effort to provide comfortable and safe conditions. The focus of this chapter, therefore, is on planning for proper containment and protection of occupants during construction/renovation and remediation plus operational aspects that are related to the built environment. New concepts of design elements and the key roles that healthcare epidemiologists (HEs) and infection preventionists (IPs) play are reviewed elsewhere in this text (see Chapter 82).
PATIENT SAFETY INITIATIVES
A decade has passed since the Institute of Medicine’s first report on patient safety in 1999 seized the nation’s attention, focusing on the importance of the healthcare environment’s effect on patient outcomes (1). The Agency for Healthcare Research and Quality was charged with developing a plan to reduce adverse outcomes and improve the safety of workers and patients. This focus on medical safety continues to develop in healthcare organizations across the United States (2). Care delivery processes occur in physical structures intended to be healing environments, enhancing patient’s health outcomes. Coincident with the emphasis on patient safety, accreditation agencies such as The Joint Commission (TJC) continue to encourage and require facilities to ensure that the environment of care (EOC) in facilities does not serve as a reservoir for pathogens. Implicit in this emphasis on the EOC is preventive maintenance for critical utility systems that deliver ventilation and water to patient-care areas.
MICROBIAL HAZARDS ASSOCIATED WITH CONSTRUCTION AND RENOVATION
The physical environment in a healthcare facility may pose risks to occupants (e.g., patients, personnel, and visitors) if enhancements to the environment are carried out without a basic understanding of the potential for creating hazards and the associated morbidity and/or mortality. Physical hazards, infectious risks among them, may occur as the result of well-intentioned designs that may have unexpected consequences. For example, HEs and IPs need to balance proposals for a water feature, such as a water wall, with potential risks of disease from waterborne opportunistic infectious agents (e.g., Legionella species). Newer designs of ventilation systems aimed at sustainability and energy efficiency must be evaluated for risks of airborne contaminants. A clearer picture of infectious hazards associated with care delivery environments has emerged over the past decades. HEs and IPs increasingly recognize that such risks occur during construction, renovation, remediation, and preventive maintenance or from damage following natural or manmade disasters. Knowledge gained from disease outbreaks and successful interventions can be incorporated by architects and engineers to improve designs, resulting in truly healing environments. It is essential that architects, engineers, HEs, IPs, infectious diseases and safety specialists, and other stakeholders balance planning for construction and renovation with a thorough knowledge of infectious hazards, preventive techniques, and effective interventions to ensure the safest and most patient-friendly environment. Lessons are learned from prior outbreak investigations and related environmental issues. Experiences do provide information on mitigating risks and designing the EOC to prevent disease transmission as designs and materials are selected and approved in a process involving infection disease expertise (3) (see Chapter 82).
Airborne Microorganisms
Most studies that have associated airborne disease transmission with demolition, construction, or renovation have involved improper or ineffective environmental containment, incorrect ventilation design, or lack of planning prior to maintenance or remediation that allowed the exposure of highly immunocompromised populations, such as bonemarrow transplant patients, to opportunistic pathogens (e.g., Aspergillus species). Exposure to airborne infectious agents (e.g., fungi) can have a severe effect on the health of patients and healthcare personnel (HCP). The mechanisms of this exposure usually involve disruption and release of contaminants into the indoor air during the demolition of existing areas or removal of existing walls or surfaces in areas where there was an incidental encounter of prior water intrusion plus subsequent fungal contamination. Construction in these situations can result in a “burst” or release of fungal conidia into the surrounding air, which can then travel through the heating, ventilation, and airconditioning (HVAC) system and result in the exposure of susceptible occupants. Insights gained from outbreak investigations involving construction/renovation activities have been used to mitigate the risks of healthcare-associated exposure. Effective interventions deployed during these outbreaks have been incorporated into recommendations for proactive planning and interventional strategies by guideline setting agencies (4,5). Selected examples of risk mitigation or prevention are summarized in this section to underscore the importance of specific design issues such as controlling the dissemination of particulates and airborne pathogens during demolition or remediation and ensuring that the design of HVAC or air-handler systems meet the needs for general and special patient-care areas (e.g., operating rooms [ORs], interventional cardiology/radiology units, airborne infection isolation rooms [AIIRs], protective environment [PE] rooms). Sources of airborne contaminants and infectious agents are closely related to water- and moisture-related conditions. Representative outbreaks are also discussed to illustrate the risk of exposure and cross-transmission of relevant infectious agents.
Construction and Dissemination of Airborne Microorganisms Air-quality management during construction is central to preventing the transmission of opportunistic microorganisms to susceptible patients, most notably highly immunosuppressed patients. Key publications of outbreaks related to the Aspergillus species and related fungi received increased attention in the 1970s and are summarized elsewhere (6,7) (see Chapter 57). The transmission of airborne infectious agents may originate from patient reservoirs, from laboratories, and from dust and soil introduced into the facilities during construction (8,9). The relationship between facility HVAC and airborne healthcare-associated infections (HAIs) is discussed elsewhere in this text (Chapter 84). Numerous studies have confirmed the process by which construction activity brings outdoor contaminants into a building normally “protected” by multiple systems. Key findings and interventions from investigations describing airborne microbial contamination associated with construction between 1976 and 2010 are summarized in Table 83-1 (10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 and 30,31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52 and 53,54,55, 56, 57, 58, 59, 60, 61 and 62,63,64,65,66,67,68).
Soil and dust become vehicles for particulates, which carry microorganisms, leading to infection and disease in specific populations. This process has been described in several excellent studies (23,24,69,70). Dust particles from excavation (aside from irritation from fumes and chemicals) become the vehicle for introducing opportunistic microorganisms into the HVAC systems (33,71).
External Demolition and Implosions
Excavation has been cited as the major problem with external demolition and implosions (72). Reports regarding the impact of large-scale demolition (e.g., implosion) have provided important information about whole-building HVAC and air pressurization (i.e., the importance of not permitting a whole building to become negative, resulting in outside air flowing into the building). Facility-associated cases of aspergillosis have been documented from temporal depressurization, in which contaminants were drawn into a facility adjacent to another building that was imploded (54,73,74) (see Chapter 84). Intrusion of contaminants during nearby building implosions produce high concentrations of dust, soil, and microbial contaminants in or on these substances; importantly, proper planning can reduce the risk from this increased burden of contaminants in outdoor air (64,65,68,75,76). Preemptive measures may include canceling elective surgery for patients at high risk, sealing windows and doors, adding extra filtering for air intake, and maintaining positive air pressure for patient-care areas where immunocompromised or other susceptible patient populations are located. Similarly, a fire in a nearby building may also have resulted in transmission of the Aspergillus species through open windows by imbedding spores in carpeting (36).
Indoor Environment
Aspergillus species and Rhizopus are among the most important fungi introduced during construction and are characterized by an ability to grow in an indoor environment under favorable temperature and moisture conditions (13,14,24). Other fungi that gain access through building penetrations include the Penicillium species, Cladosporium species, and similar airborne contaminants (33,70,77). Reservoirs of these may also be created in the indoor environment from the undetected intrusion of water into walls or cabinetry in patient-care units.
Air Handlers
Many publications have addressed the importance of appropriate measures for the containment and protection of air-handling units (AHUs) during construction to reduce the risk of transmission of airborne pathogens such as the Aspergillus species to susceptible patients. Appropriate containment may include zonal use of portable high-efficiency particulate air (HEPA)-filtered air (used in negative air machines), provision of negative air pressure (39,45,78,79), dedicated exhaust, and physical isolation of the construction area from patient-care areas (24,32,40). Numerous patient outbreaks of bacterial and fungal infections associated with aerosols from contaminated ventilation ducts, grills, damaged barriers (e.g., bird screens, ventilation fans), and vacuum cleaners reinforce the importance of maintaining an intact air-handling system (11,43,50).
Room Design and Location Room design must consider the location of supply air and exhaust vents as critical factors to interrupt the risk of transmitting airborne contaminants (33,41). Negative air pressure in pediatric oncology units, for example, was shown to reduce the spread of varicella-zoster virus (VZV) among workers and patients (16). Lower bloodstream-infection and mortality rates were reported for burn patients in enclosed intensive care unit (ICU) beds than for patients in open wards (80). Multiple outbreaks related to Mycobacterium tuberculosis were terminated with properly designed and improved maintenance of negative air pressure (AII) rooms (81).
The Surgical Suite Environment The OR environment has been studied extensively in an attempt to reduce infectious risks in patients undergoing clean surgical procedures such as orthopedic joint replacement. Other invasive procedures are increasingly being performed in a variety of locations such as procedure rooms, which mirror the desired conditions in an OR, and so the scope of this setting needs to extend beyond the surgical suite (67).
The literature on reductions in surgical site infection (SSI) rates, primarily found in total joint arthroplasty, is reviewed elsewhere (82, 83 and 84). The focus for this chapter relates to contamination of the OR during construction and renovation from airborne fungi and other pathogens (27,28,31,85,86,87,88, 89, 90, 91 and 92). A summary of the general issues and interventions to mitigate these problems have been reported elsewhere (8,9,28,89,93) (see Chapter 84). Multiple interventions in ORs have led to improvements in performance and outcome involving surgical patients. Many of these emphasize optimizing air quality and exchange. As a result, current standards include increased outside air and total air exchanges per hour, improved air filtration efficiency, proper humidification, and filter location in air handlers serving ORs (4,15,31,42). Major studies by Lidwell (94,95) focused on the use of ultraclean (laminar airflow [LAF]) HEPA-filtered air in clean orthopedic surgical procedures. These studies, together with other multisite studies (87,96), led to a better understanding of the independent contribution of ultraclean air in reducing clean SSIs; its effect is comparable to the use of preoperative prophylactic antibiotics. Although LAF using HEPA filtration has been considered for specific procedures such as orthopedic surgery, given the major resultant morbidity and mortality if the replaced joint becomes infected, definitive evidence on the efficacy of elaborate LAF in the prevention of SSIs has been lacking. The Centers for Disease Control and Prevention (CDC) 2003 guidelines, assessing available scientific literature, concluded: “No recommendation is offered for performing orthopedic implant operations in rooms supplied with laminar airflow …” (97). Brandt et al. recently published a multihospital study in Germany that suggested an increased risk of SSI was associated with ORs using LAF compared to standard turbulent-air ORs (98). Details of specific HVAC design at the participating hospitals are lacking in this investigation; however, these systems were older, vertical, high-velocity LAFs and are not comparable to the current design required in the United States in the 2006 Facility Guidelines Institute (FGI) guidelines (99) and the latest 2010 FGI guidelines (4) that use a low-velocity unidirectional airflow (100). For complete information on this design, see Chapter 82.
Waterborne Microorganisms
Water can be a reservoir of pathogens that can cause waterborne diseases but can also harbor other microbes (e.g., Fusarium spp. and Aspergillus spp.) that may propagate in the environment. Those at greatest risk are immunocompromised patients, and many outbreak investigations have identified potable water systems and storage tanks, showerheads, and ice machines as sources of waterborne pathogens (101, 102, 103 and 104). Table 83-2 summarizes findings from investigations of clusters of infection caused by waterborne pathogens (103,105, 106, 107, 108, 109, 110, 111, 112 and 113,114, 115, 116, 117, 118, 119, 120, 121 and 122,123,124,125,126). Legionella species, for example, have been implicated in patient infections acquired through the inhalation of aerosols spread from contaminated storage tanks, shower heads, and equipment that used tap water, such as water baths, stagnant water on the roof (124), decorative water fountains (126), and/or entire water systems (114,127, 128, 129, 130 and 131). A review of healthcare-associated waterborne infections excluding those caused by Legionella species revealed 43 outbreaks with associated deaths of almost 1,400 per year and called for the provision of sterile rather than potable water for high-risk patients during hospitalization (132). Maintenance of potable water quality depends on good design, preventive maintenance, and conduits that support dynamic movement in a continuous fashion. Problems arise when portions of water-delivery systems are capped, permitting water to stagnate, and both biofilm and concentrations of microbes increase to high levels. Surveillance for HAIs related to water reservoirs, therefore, is an important component of the design and operation of this major utility. One study assessed the risk of bacterial pathogens in drinking water in an attempt to determine if dose-response relationships could be developed, and whether or not potable water poses a public health hazard (133). The results included a ranking of water-associated microorganisms from studies reported primarily from medical centers. Although the purpose of the study was not directly related to construction, the review does confirm the expected frequency of opportunistic microorganisms causing serious infections associated with water. These opportunistic microorganisms are of concern because of their potential for direct or indirect transmission from taps and sinks or through the inhalation of aerosols generated from construction activities affecting patients and construction workers (124). One recent outbreak of Pseudomonas aeruginosa in an ICU and transplant unit resulted in serious morbidity and mortality due to water from sink drains contaminating patients and clean supplies (125). See Chapter 82 for complete details of how sink modifications ended the outbreak. Even contaminated condensation from window air-conditioning units when combined with other work practices can lead to invasive infections such as the Acinetobacter species bloodstream infections in high-risk pediatric populations (134).
Moisture and Fungi Excessive moisture around pipes and insulation, condensation in drain pans, and flooding from broken pipes can lead to extensive environmental fungal contamination. Such contamination has been associated, for example, with water-soaked cabinets in medication rooms (23,62). Static water systems can provide a reservoir of microorganisms in the healthcare environment by supporting their growth. Nonsterile water used for invasive patient-related procedures can result in direct or indirect transmission of microorganisms to patients (103,109,135). Bloodstream infections due to the mold Phialemonium curvatum were identified in a hospital hemodialysis unit in which the product water was determined to be the source. Resolution required discontinuing the use of waste-handling option ports (125). A report of fungal endophthalmitis from Acremonium kiliense following cataract surgery in an ambulatory surgery setting demonstrated the process by which contaminated humidifier water functioned as a reservoir for an infectious agent, eventually spreading through the airborne route by way of the ventilation system (42). Typically, healthcareassociated transmission of fungi is airborne; however, there is emerging evidence that potable water in health facilities may also be a significant reservoir, suggesting that prompt disinfection of high water-use areas such as showers is an important measure to prevent exposure to fungal pathogens (136).
