Visualization of hospital cleanliness in three Japanese hospitals with a tendency toward long-term care
- Reina Watanabe†1,
- Tomoko Shimoda†1,
- Rika Yano†1,
- Yasuhiro Hayashi2, 3,
- Shinji Nakamura4,
- Junji Matsuo2 and
- Hiroyuki Yamaguchi2Email author
© Watanabe et al.; licensee BioMed Central Ltd. 2014
Received: 15 February 2013
Accepted: 30 January 2014
Published: 4 March 2014
Hospital cleanliness in hospitals with a tendency toward long-term care in Japan remains unevaluated. We therefore visualized hospital cleanliness in Japan over a 2-month period by two distinct popular methods: ATP bioluminescence (ATP method) and the standard stamp agar method (stamp method).
The surfaces of 752 sites within nurse and patient areas in three hospitals located in a central area of Sapporo, Japan were evaluated by the ATP and stamp methods, and each surface was sampled 8 times in 2 months. These areas were located in different ward units (Internal Medicine, Surgery, and Obstetrics and Gynecology). Detection limits for the ATP and stamp methods were determined by spike experiments with a diluted bacterial solution and a wipe test on student tables not in use during winter vacation, respectively. Values were expressed as the fold change over the detection limit, and a sample with a value higher than the detection limit by either method was defined as positive.
The detection limits were determined to be 127 relative light units (RLU) per 100 cm2 for the ATP method and 5.3 colony-forming units (CFU) per 10 cm2 for the stamp method. The positive frequency of the ATP and stamp methods was 59.8% (450/752) and 47.7% (359/752), respectively, although no significant difference in the positive frequency among the hospitals was seen. Both methods revealed the presence of a wide range of organic contamination spread via hand touching, including microbial contamination, with a preponderance on the entrance floor and in patient rooms. Interestingly, the data of both methods indicated considerable variability regardless of daily visual assessment with usual wiping, and positive surfaces were irregularly seen. Nurse areas were relatively cleaner than patient areas. Finally, there was no significant correlation between the number of patients or medical personnel in the hospital and organic or microbiological contamination.
Ongoing daily hospital cleanliness is not sufficient in Japanese hospitals with a tendency toward long-term care.
KeywordsHospital cleanliness ATP bioluminescence Stamp agar culture method Long-term care Japan
Much attention has been focused on hospital-acquired infections in the last decade [1–3]. These infections can be acquired from microbe-contaminated hospital environments that are frequently touched by hands, namely “high-touch surfaces,” including doorknobs, guardrails in corridors, and overbed tables of inpatients . Such sites are thought to provide the greatest risk for patients . Therefore, efforts to improve hand hygiene and isolation practices have been implemented to help mitigate this problem on a worldwide scale, particularly in developed countries . In fact, recent studies have shown that routine cleaning practices in hospitals are associated with a decrease in transmission of vancomycin-resistant Enterococcus or methicillin-resistant Staphylococcus aureus[4–7], suggesting a significant implication of hospital cleanliness in the control of hospital-acquired infections.
According to this concept of hospital cleanliness, recommendations and standards to improve hospital cleanliness have dramatically evolved. Several guidelines [8–10], such as those of the Centers for Disease Control and Prevention , strongly insist on the need for infection prevention and control programs, including appropriate monitoring of medical staff and housekeeping activities related to hospital cleanliness, to control hospital-acquired infection and predict the risk of patient infection. These guidelines similarly recommended cleaning and disinfection of surfaces in close proximity to the patient and those that are likely to be touched by the patient and medical staff members or housekeepers, although visual assessment of hospital cleanliness is still popular and has been believed to be linked with reduction of infection. In addition, both adenosine triphosphate (ATP) bioluminescence (ATP method) as indicators of general organic contamination [11–15] and the standard stamp agar method (stamp method) for monitoring microbiological contamination [16–18] have been available for monitoring hospital cleanliness.
Compared with other developed countries such the United States and countries in Europe, the average number of bed disability days in Japan hospitals is at least twice as high (approximate average, 19 days) as indicated by OECD health data . This indicates that Japan hospitals have a tendency toward long-term care and evoke strong caution regarding hospital-acquired infections. Thus, the concept of hospital cleanliness to control hospital-acquired infection is well understood in Japan and other countries. However, in Japanese hospitals, daily hospital cleanliness has been limited to visual assessment with wiping, ignoring the hospital characteristic of long-term care, and more importantly has not been sufficiently supported by evidence-based studies on monitoring hospital cleanliness with a large amount of data.
In the present study, to define the actual conditions of cleanliness in Japan hospitals with a tendency toward long-term care, we attempted to visualize hospital cleanliness by testing 752 surfaces in three hospitals with both the ATP and stamp methods over a 2-month period.
Assessment of the number of medical personnel and hospital inpatients
During the experimental period, we recorded the number of medical personnel (nurses and nurse aids) and hospital inpatients in each of the wards at the time of sample collection. No significant change in the number of patients or medical staff personnel (nurses, medical doctors, or medical assistants) per day among the wards was found in any of the hospitals. The total average number of patients and medical staff personnel per day in each hospital during the study period was 61.3 ± 9.9 (“A” hospital), 48.6 ± 6 (“B” hospital), and 30.7 ± 4 (“C” hospital), although these numbers changed depending upon the hospital size.
Visual assessment and wiping
All of the hospitals had an ongoing program for hospital cleanliness comprising visual assessment according to a checklist (visual dirt, rubbish, smears, dust, grease, blood, fingerprints, and clinical waste on clinical surfaces) as previously described  and wiping with detergents such as Magiclean (Kao, Tokyo, Japan). The latter component of the program (wiping with detergents) included wiping of floors with disinfectants (e.g., Dimension II; Butcher, Marlborough, MA, USA) and wiping of other places such as lockers or overbed tables with neutral detergents after wiping with disinfectants (e.g., Dimension II). In all hospitals, there were no differences in cleaning method or frequency between the nurse and patient areas.
ATP method and evaluation of detection limit
Stamp method and evaluation of detection limit
Commercial stamp agar based on soybean casein digest (Clean Stamp with 10-cm2 surface area; Nissui Pharmaceutical Co., Ltd., Tokyo, Japan) for monitoring environments for microorganism contamination was used for the assay (Figure 2C). The stamp method was performed in parallel with the ATP method. The agar plate was cultured for 5 to 7 days under aerobic conditions with moisture at 30°C, and colonies were counted. The data were estimated as CFU per 10 cm2. The stamped agar plates were immediately cultured. The data obtained as CFU were expressed as the fold change over the detection limit estimated as follows. The detection limit of the stamp agar method was examined on randomly chosen student tables (n = 19) in a lecture room of our department (Faculty of Health Sciences, Hokkaido University) during winter vacation. The samples used to determine the detection limit were collected from each table before and 2 min after treatment with a neutral detergent (Magiclean; Kao). Data are expressed as CFU per stamp: total of values obtained before and after treatment are used as the detection limit.
The need for ethical approval was waived by the ethical committee of each hospital in this study. Meanwhile, before collecting samples or data, we explained the study design, and informed consent was orally obtained from all medical staff members and hospital inpatients intending to participate in this study. Furthermore, during sample or data collection, we protected the privacy and confidentiality of personal information under supervision of each of the hospital managers and in accordance with the Helsinki Declaration .
Comparison of bacterial contamination levels (percentage or relative fold change) was assessed by Student’s t-test. Spearman’s correlation index r was calculated using statistical analysis software [SPSS Statistics (15.0 J), IBM, Tokyo, Japan]. A p value of <0.05 was considered to be statistically significant.
Results and discussion
Determination of detection limits for ATP and stamp methods
We found that the ATP values increased when the spiked bacterial numbers were more than 10,000 CFU, indicating that the bacterial detection limit of the ATP method was very low. This is not surprising because a trait of the ATP method is detection of residual ATP, not only microbial contamination, in “high-touch sites” as an indicator of general organic contamination [11–13]. Moreover, it has been noted that the use of the ATP method to rapidly monitor hospital cleanliness clearly increased the motivation of domestic staff or housekeepers via education and monitoring with feedback, demonstrating an indirect connection with the reduction of key environmental organisms [23, 24]. Therefore, the ATP method has become the most popular method available for monitoring hospital cleanliness [11–15].
We also confirmed that the higher sensitivity of the stamp method is an advantage over the ATP method in terms of precisely monitoring microbiologic contamination of hospitals. Although the stamp culture could not identify all organisms (for instance, it was not possible to identify anaerobic microorganisms), the aerobic culture condition that we used could identify most microorganisms related to hospital infection. Therefore, the stamp method is an appropriate and effective monitoring system for evaluating microbiological contamination associated with high-touch sites of hospitals, allowing for direct detection of hospital-acquired pathogens. Thus, because monitoring with a combination of the ATP and stamp methods could provide advantages in terms of covering a wide range of potential threats to adequate hospital cleanliness, both methods were used in this study.
Positive frequencies of the ATP and stamp methods in hospital environments
Cleaning a crowded public area of a ward with isolation rooms containing patients is reportedly far more complex than cleaning offices such as nurse stations [22, 25]. To confirm this, we compared nurse (N1–3 or N1–4) and patient areas (P1–8) in each of the hospital units, hypothesizing that nurse areas were cleaner than patient areas because patient areas contain more medical personnel and inpatients. As expected, a significant difference between nurse and patient areas was found using the stamp method (8 units, p < 0.05) and the ATP method (4 units, p < 0.05) (Figures 4 and 5, right panels). These results indicate that maintaining hospital cleanliness of inpatient areas with more complicated medical personnel is difficult, supported by previous study .
Interestingly, the data of both the ATP and stamp methods demonstrated considerable variability, regardless of daily visual assessment with usual wiping or cleaning. In addition, positive surfaces were often but irregularly seen, although the exact reason why hospital contamination by organic matter or microbes irregularly occurred remains unknown. Furthermore, guidelines emphasize the importance of hospital cleanliness [8–10], but give little practical advice on how to achieve this. Medical staff members, including nurses, may be too busy to properly clean furniture and equipment, and medical care support is considered to be of higher priority than wiping or cleaning the tops of lockers or overbed tables. Medical staff members’ workloads may reach critical limits in Japanese hospitals, as well as those in other developed countries [22, 25]. Antimicrobial coatings containing heavy metals or biocides are currently available for items such as clothes, linen (sheets and curtains), furniture (lockers and overbed tables), and high-touch sites [26–28]. These new, innovative products could be expected to successfully achieve appropriate hospital cleanliness under the present medical and housekeeping activity levels.
Correlation index between either ATP or stamp values and number of either staffs or hospital inpatients
Pearson’s correlation index
Although cleaning within hospitals is a major budget item, there are currently few accurate data with which to judge cleaning efficacy, as mentioned above. Our results caution against the popular belief that regular visual assessment with wiping is sufficient for maintaining hospital cleanliness in Japan hospitals with a tendency toward long-term care.
The visualized cleanliness of Japanese hospitals showed considerable variability, suggesting insufficient ongoing daily cleaning. Based on certain monitoring parameters of hospital cleanliness using the ATP or stamp method, further cleaning tasks or definite role sharing for medical staff members and housekeepers, in conjunction with new techniques such as material coatings, should be considered to maintain adequate hospital environments in facilities with a tendency towards long-term care, such as those in Japan.
We thank the staff members of the Departments of Medical Laboratory Science and Nursing, Faculty of Health Sciences, Hokkaido University, for their assistance throughout this study.
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