Introduction

Environmental cleaning (EC) is a fundamental principle of preventing infection in the hospital setting. Both porous surfaces (e.g., mattresses) and nonporous surfaces (e.g., bed rails) in patient rooms are highly susceptible to bacterial contamination with dangerous pathogens, including Clostridium difficile, and antibiotic-resistant organisms such as methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), and multiple species of Acinetobacter (Acinetobacter spp). Hard, nonporous surfaces, which include common items such as furniture, bed rails, and medical equipment, as well as fixed spaces like floors and bathroom facilities, form part of the environmental reservoir that can lead to significant microbial contamination. The potential for these contaminated environmental surfaces contributing to transmission of pathogens has been most clearly established for certain key health-care-associated pathogens, including MRSA, VRE, C. difficile, and Acinetobacter spp.^1-4 These nosocomial pathogens can survive on inanimate surfaces for prolonged periods. For example, gram-positive organisms such as MRSA and VRE have been shown to persist on dry surfaces for several weeks to months.^5-7 C. difficile spores have been shown to survive in the environment for as long as 5 months.⁸ Appropriate cleaning of these surfaces is an important part of an overall strategy to reduce the risk of health-care-associated infections (HAIs). However, little consensus exists for optimal approaches to EC. Both the physical action of cleaning surfaces and applying a disinfectant are critical in reducing microbial burden on surfaces. In this report, we use “cleaning” to refer to removal of general surface debris and “disinfection” to refer to use of agents or technologies designed to kill microbial organisms. The term “environmental cleaning” refers broadly to the organized processes employed by hospitals for cleaning, disinfecting, and monitoring.

A wide variety of cleaning agents and disinfection technologies are commercially available, each with potential benefits and disadvantages. Additionally, hospitals often monitor the quality of room cleaning and disinfection to ensure that surfaces have been treated appropriately. Several monitoring strategies exist, which range from simple visual inspection, to microbiologic testing of surface contamination, to technologic innovations that measure the adequacy of surface cleaning. As the variety of options for cleaning, disinfecting, and monitoring grow, hospitals are faced with many choices, but limited evidence exists on the comparative effectiveness of these interventions, especially related to HAI rates within the hospital. This Technical Brief is designed to summarize and map the current evidence base addressing EC to prevent HAIs and highlight future research needs.

Disinfection Strategies

A wide variety of chemical disinfectants have been approved for use in the hospital setting. The most commonly used surface disinfectants are quaternary ammonium compounds (QACs, often referred to as “quats”) and sodium hypochlorite (commonly known as bleach). Other agents that have been introduced for surface disinfection include peracetic acid and accelerated liquid hydrogen peroxide. The effectiveness of chemical disinfectants can depend upon both the antimicrobial activity of the disinfectant and appropriate application, including adequacy of cleaning, contact time, and concentration of the disinfectant. In addition to these manually applied chemicals is the use of “no-touch” modalities for hospital room disinfection, including application of ultraviolet light (UV-C)^9-11 or fogging with hydrogen peroxide vapor or mist.^12-14 These processes can be used only for terminal disinfection when patient rooms are empty and must be preceded by adequate room cleaning. Another strategy is the adoption of “self-disinfecting” surfaces that are impregnated or coated with copper, silver, germicides, or other antimicrobial-releasing agents.^15,16 These surfaces are designed to resist contamination and augment routine cleaning processes.

Assessing Disinfection Following Environmental Cleaning

In addition to selecting effective cleaning and disinfection methods, hospitals also assess how effectively such processes are being implemented. Visual inspection is the simplest method for evaluating cleanliness, but concerns about the adequacy of visual inspection alone^17-19 have fostered the development of technology-based approaches. Several strategies have emerged that may improve the quality of visual assessment but introduce additional expense and other potential disadvantages. One such alternative is to collect specimens from surfaces and measure aerobic colony counts, which is a culture-based method for assessing surface microbial contamination. Another technique is the use of invisible fluorescent markers placed on room surfaces before cleaning and disinfection, with UV light inspection afterward. This approach provides immediate, direct feedback. Bioluminescence-based adenosine triphosphate (ATP) assays have been developed as another alternative that offers direct, rapid feedback and provides a quantitative measure of cleanliness. However, the detected presence of ATP does not necessarily indicate viable pathogens on the tested surface. In addition, universal cutoffs for ATP levels and “cleanliness” have not been established. Lastly, some studies have shown that certain disinfectants can interfere with ATP readings.^20-22

A related and important consideration is the desire to establish standardized criteria for determining “clean” surfaces on the basis of each monitoring modality. While routine cleaning and enhanced disinfection strategies will not result in a sterile environment, consensus is lacking on the threshold of contamination below which pathogen transmission is minimized and can be considered safe. Establishing an evidence-based benchmark for defining a surface as clean will depend on the patient population, current cleaning and disinfection processes, and specific pathogen(s) being targeted.

Programmatic Monitoring of Environmental Services Personnel

Monitoring the operational processes associated with environmental services (EVS) and properly training and managing the staff charged with these duties are also necessary for preventing transmission of HAIs. Strategies for assessing compliance may include use of checklists, direct observation (open or covert), and surveys of personnel and patients. Process evaluation and improvement may also consider important human factors and logistical concerns, including workflow, staffing, staff training and supervision, collaboration between support services and clinical staff, institutional leadership, and patient preferences. Finally, sustaining long-term improvement is a critical but challenging goal as EVS personnel are continuously faced with pressure to clean occupied rooms and turn over terminal rooms.

Clinical Settings and High-Touch Surfaces

EC can be examined very broadly. Concern about HAIs extends far beyond acute care hospital patient rooms. Routine cleaning is necessary to ensure patient safety in every health care setting, including surgical suites and other procedure areas, diagnostic testing sites, long-term care facilities, rehabilitation centers, outpatient physician offices, and others. This Technical Brief's scope of interest, however, is limited to rooms that house hospitalized adult patients. Preventing infections during hospitalization is a primary goal of current initiatives by hospitals, clinicians, payers, regulators, and patient advocates. Additionally, hospital inpatient wards are complex settings, clinically and logistically, and merit consideration apart from other sites.

Similarly, the environmental reservoir that carries infection risk encompasses much more than a few surfaces in a patient room. Vectors for disease transmission may include medical instruments like endoscopes, fabric surfaces such as linens and patient privacy/room curtains, and the many people a patient encounters daily, including health care providers, ancillary services, visitors, and other patients. This Technical Brief is limited to cleaning and disinfection techniques used on the hard surfaces that form a fixed part of the patient room environment and are frequently touched by the patients and providers, which are often categorized as “high-touch surfaces” or “high-touch objects” (HTOs). Examples include bed rails, trays, call buttons, intravenous (IV) poles, doorknobs, floors, and bathroom facilities. Much of the available research on EC focuses on these types of surfaces, and strategies for ensuring their cleanliness differ from how soft fabrics are laundered or invasive instruments are sterilized.

Primary Pathogens

Hospitals serve as hosts to a wide array of diseases and pathogens. This Technical Brief focuses on evidence for strategies that may prevent transmission of three of the most common pathogens causing HAIs and for which there is significant evidence for surface contamination: C. difficile, MRSA, and VRE. Many studies of surface disinfection and monitoring have concentrated on removing and/or killing these organisms.

Guiding Questions