Healthcare facilities should implement measures to optimise environmental hygiene, especially given the finding that success can be achieved without substantially increasing outlay on personnel
Philip Carling MD Director of Hospital Epidemiology
Carney Hospital Boston University School of Medicine
The continued increase in the incidence of antimicrobial-resistant infections represents one of the most serious problems facing healthcare in Europe today. Despite extensive efforts to limit the healthcare-associated transmission of resistant, highly infectious and often lethal pathogens such as methicillin-resistant Staphylococcus aureus (MRSA), vancomycin- resistant enterococcus (VRE), Clostridium difficile (C difficile), Acinetobacter baumannii
(A baumannii) and noroviruses, hospitals in Europe have experienced ongoing and often escalating problems with one or more of these hospital-associated pathogens (HAPs) during the past decade.
Along with efforts to improve antibiotic stewardship in many countries, several national healthcare systems have implemented interventions to detect and isolate MRSA-colonised and infected patients. While this has resulted in sustained reduction in MRSA infections, overall nosocomial infection rates have not improved, suggesting that such measures may alter the epidemiology of healthcare-associated infections in these countries while only partly improving patient safety. Furthermore, the cost and logistical challenges of widespread implementation of pathogen-specific active surveillance/isolation programmes in the setting of escalating rates of healthcare-associated infections caused by pathogens other than MRSA, particularly C difficile and VRE, will further limit the role of pathogen-specific interventions over time.
Although the use of alcohol-based hand rubs has had a favourable impact on the transmission of several HAPs, achieving compliance with recommended hand hygiene practices has proven quite challenging. In addition, the substantial logistical challenge of optimising hand hygiene while providing direct patient care, particularly in the intensive care unit setting, along with the documented role of both gloved and ungloved hands in the transmission of HAPs between environmental surfaces and patients, may limit its impact.
Recent studies suggest that improving environmental hygiene in the “patient zone” – the patient and those surfaces contacted by healthcare workers in patient care activities – may represent an underappreciated opportunity to enhance current efforts to control the transmission of HAPs to susceptible patients.
For more than a century, there have been concerns that patients may be at risk of acquiring infections from the hospital environment. Such concerns led hospitals to develop policies and procedures for wet mopping and surface cleaning of patient rooms and operating suites, to eliminate visible soil while decreasing the bio-burden bacterial pathogens on surfaces. Although the value of such practices was reinforced by experiences during outbreaks of penicillin-resistant Staphylococcus aureus transmission in hospitals during the 1950s, the poor yield of randomly collected environmental cultures led to the belief that the patient environment was not implicated in infection transmission.
This perspective began to be questioned when widespread environmental contamination of near-patient surfaces was consistently found during C. difficile outbreaks in the 1980s. Subsequently, studies were undertaken to evaluate the frequency with which other HAPs contaminate such surfaces. It has now been well documented that approximately 30% of surfaces in the patient zone of individuals colonised or infected with C. difficile, VRE or MRSA are contaminated with these organisms.
Several reports have confirmed similar rates of contamination with A. baumanii in rooms of colonised or infected patients. While the complexity of the PCR technology required to detect noroviruses has limited research, several reports have documented their presence on surfaces in healthcare settings during outbreaks. In addition to the frequency with which surfaces in the patient zone become contaminated with HAPs, all of the pathogens most implicated in transmission-associated hospital infections survive for prolonged periods of time on dry surfaces at ambient temperatures. In contrast, environmentally fragile pathogens such as aerobic and anaerobic enteric bacteria are rarely associated with spread between patients in healthcare settings.
The discovery of widespread environmental contamination of surfaces in patient areas during C difficile outbreaks, along with the realisation that infectious C difficile spores can survive in the environment for many months, led to successful efforts to bring such outbreaks under control through enhanced environmental disinfection cleaning. An increased understanding of the importance of environmental hygiene in the transmission of C difficile infection has led to the widespread adoption of chlorine-based disinfectants for cleaning potentially contaminated surfaces.
Despite the sporicidal effectiveness of these disinfectants, a recent study showed that the rate of contamination of surfaces such as bedrails, bedside tables, toilet surfaces and similar objects in C difficile-infected patient rooms decreased to only 44% from 56% after routine cleaning using a sporicidal disinfectant.6 The subsequent finding that contamination was significantly reduced (p < 0.01) after educating the environmental services staff confirmed the effectiveness of the cleaning system and raised concerns that routine cleaning may previously have been suboptimal.
Previously a relatively uncommon HAP, VRE is becoming more prevalent in many European Union countries. Although it had previously been assumed that antibiotic selection pressure was the major factor accounting for the emergence of this organism, new studies have clarified the role of environmental transmission.
Most recently, Dress and colleagues undertook a prospective, interventional crossover study of VRE transmission during one year in an ICU setting where it was found that the strongest predictors of VRE acquisition were a prior positive room culture for VRE and prior room occupancy by VRE-colonised patients (a presumed proxy for room contamination). Furthermore, this effect persisted for as long as two weeks when at least one and possibly several “terminal cleanings” had occurred.
These results further support a previous in-depth analysis of the epidemiology of VRE acquisition. This study found that improving environmental cleaning measures was significantly associated with decreased surface contamination by VRE and less VRE contamination of healthcare workers’ hands, and this was the only intervention that led to a significant reduction in VRE transmission to susceptible patients.
Other studies have confirmed the transmission of MRSA and Acinetobacter from prior room occupants to susceptible patients as well as transmission of specific strains of MRSA directly from the environment to patients. There is also
extensive historic support for the likely probability that suboptimal environmental hygiene plays a significant role in the transmission of S aureus, particularly MRSA, in healthcare settings.
Improving environmental hygiene
Given the probability that suboptimal thoroughness of environmental disinfection cleaning contributes to the ongoing transmission of HAPs, an indirect targeting method was developed to study and possibly improve the thoroughness of environmental hygiene. The targeting system was initially used to evaluate the thoroughness with which 13 standard surfaces such as bedrails, bedside tables, toilet area handholds and so on were cleaned as part of routine disinfection cleaning during terminal-patient room cleaning in three hospitals. When it was found that many surfaces, often those most likely to be contaminated by enteric pathogens such as C difficile, VRE, MRSA and noroviruses, were frequently being cleaned less than half of the time, educational and programmatic interventions as well as objective performance feedback using further evaluation cycles were carried out in each hospital. Subsequently, the overall thoroughness of cleaning improved from 47% at baseline to 83% following interventions.
As a result, a voluntary group of infection control practitioners (the Healthcare Environmental Hygiene Study Group) agreed to undertake a standardised assessment of the thoroughness of terminal room cleaning in their hospitals. Pre-intervention analysis of the first 23 hospitals studied disclosed opportunities for improving environmental hygiene in all hospitals (Figure 1). Subsequently, the use of an intervention process identical to that used in the pilot study led to an overall improvement in the thoroughness of cleaning to 77% (p < 0.001 for the group) (see Figure 2). This improvement was realised without additional environmental services personnel in all but two of the study hospitals. Due to these studies, projects to evaluate and improve environmental hygiene in settings such as the operating suite, adult and neonatal intensive care units, ambulatory settings and long-term care facilities, as well as an initiative to use the system as part of a statewide, CDC-supported, MRSA intervention programme in Iowa, have been implemented.
While future studies will need to broadly quantify the impact of improved disinfection cleaning on environmental contamination and the transmission of HAPs to susceptible patients, there is no reason why healthcare facilities should not take measures to optimise environmental hygiene, particularly given the finding that hospitals are able to greatly improve the thoroughness of such activities without substantially increasing personnel resources.
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