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Comparison of Fluorescent Marker Systems with 2 Quantitative Methods of Assessing Terminal Cleaning Practices
Abstract and Figures
To compare fluorescent markers with aerobic colony counts (ACCs) and an adenosine triphosphate (ATP) bioluminescence assay system for assessing terminal cleaning practices.
A prospective observational survey.
A 500-bed university-affiliated community teaching hospital.
In a convenience sample of 100 hospital rooms, 5 high-touch surfaces were marked with fluorescent markers before terminal cleaning and checked after cleaning to see whether the marker had been entirely or partially removed. ACC and ATP readings were performed on the same surfaces before and after terminal cleaning.
Overall, 378 (76%) of 500 surfaces were classified as having been cleaned according to fluorescent markers, compared with 384 (77%) according to ACC criteria and 225 (45%) according to ATP criteria. Of 382 surfaces classified as not clean according to ATP criteria before terminal cleaning, those with the marker removed were significantly more likely than those with the marker partially removed to be classified as clean according to ATP criteria (P = .003).
Fluorescent markers are useful in determining how frequently high-touch surfaces are wiped during terminal cleaning. However, contaminated surfaces classified as clean according to fluorescent marker criteria after terminal cleaning were significantly less likely to be classified as clean according to ACC and ATP assays.
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... 15 Common monitoring methods focus on snapshots of disinfection status 16 and include visual inspection, bioluminescent assays, aerobic colony counts, adenosine triphosphate assays, and real-time PCR assays. [17][18][19][20][21] In addition to the episodic nature of the data, the accuracy of visual monitoring of disinfection is limited by inter-observer variables, the Hawthorne effect, and is labor intensive. 22 An automated system that can continuously record and track disinfection events of PME is less labor intensive, and could mitigate the limitations of episodic and potentially biased monitoring. ...
... Direct methods of monitoring PME cleaning/disinfection include visual monitoring, fluorescent tagging or by using adenosine triphosphate detection methods, and microbiological sampling methods. [17][18][19][20] These methods are mostly episodic, require personnel involvement, may be prone to errors, and be subject to the Hawthorne effect. Compared to these monitoring methods, the DTS has several advantages because it is a continuous automated manual disinfection recording device that can be attached to an individual PME and record the cleaning and/or disinfection data without the need for monitoring of staff compliance by a supervisor. ...
Background
Portable Medical Equipment (PME) such as workstations-on-wheels (WOWs) and vital signs machines (VMs) have been linked to healthcare-associated infections. Routine visual monitoring of PME disinfection is difficult. An automated Disinfection Tracking System (DTS) was used to record and report the number of disinfection events of PME in a hospital setting.
Methods
The study was conducted in 2 acute-care units for 25-days to determine the pattern of recorded events from DTS on PME. Devices record disinfection events as moisture events and automatically store on a central database. DTS devices with “screen-on” feedback and “screen-off” devices with no display were placed on 10 WOWs and 5 VMs on separate units.
Results
A total of 421 moisture events were recorded for the “screen-on” and 345 for the “screen-off”, during the 25-day implementation period on the 2 different hospital units. The highest number of events occurred between 6:00am-7:00am, with 69 & 75 moisture events recorded for Units 1 and 2, respectively.
Conclusions
The pattern of disinfection events for WOWs and VMs demonstrated that most events occurred regularly at the times corresponding with nursing shift change. The DTS has the potential to continuously record, and report data related to PME disinfection.
... Environmental tagging has recently emerged as a low cost, low skill mechanism for assessing cleaning while being a better proxy of successful disinfection than visual inspection alone and equal or better than higher cost alternatives, such as ATP bioluminescence (Carling et al. 2006a, Boyce et al. 2011, Luick et al. 2013. The method involves "tagging" (marking) surfaces with a fluorescent dye, which can be easily removed from a surface by regular cleaning. ...
... In human health care settings, DAZO (Ecolab) is frequently used in environmental tagging research (Boyce et al. 2011, Carling et al. 2014, Carling & Herwaldt 2017. DAZO is applied with an attached applicator that consistently produces a circular tag (mark) the size of its foam tip (~2 cm diameter). ...
Staphylococci are inhabitants of skin and mucous membranes with Staphylococcus pseudintermedius (SP) and Staphylococcus aureus (SA) serving as important pathogens for animals and people, respectively. Previous research has identified the environment as potentially important in hospital‐associated infections and zoonotic transmission in veterinary settings. The objective of this pilot study was to determine the longitudinal prevalence over repeated samplings of environmental coagulase‐positive Staphylococcus (CPS) in a new veterinary hospital and evaluate associations between contamination and environmental and clinical (caseload, cleaning checklists and staff numbers) factors. Cleaning and disinfection compliance, based on staff‐completed checklists, were reviewed for the three shifts immediately prior to sampling. We hypothesized that over time, environmental contamination would increase as the clinic developed and caseload increased and compliance to cleaning checklists would decrease with increasing caseload. Over 18 months, 351 environmental samples were collected at five sampling times (sampling occurred before opening the hospital and every 3 to 6 months thereafter). Overall contamination with CPS was 30.8% (108/351), with SA (16.8%) and SP (13.1%) identified from the contaminated surfaces. Overall, methicillin‐resistant strains (MRSA and MRSP) were infrequently recovered (combined n = 3; <1%). Point prevalence of CPS contamination was relatively stable over the study period (22.5%–28.4%), with the exception of an increase at the fourth sampling (52.9%). Cleaning compliance varied over the study period (57.9%–100%); the lowest reported cleaning coincided with the highest proportion of CPS contamination. The most commonly contaminated surfaces were chairs (7/15; 46.7%), examination tables (19/47; 40.4%) and computers (12/35; 34.3%); these items were infrequently included on cleaning lists. Surfaces not included in the checklist were 2.3 times more likely to be contaminated by CPS than those that were included (OR: 2.3, CI 95%: 1.02 –5.35, p‐value=.04). MRSA and MRSP were rarely isolated from the environment in the newly opened hospital, indicating it may take time for resistant strains to enter the environment and persist on surfaces. This study identified the possible utility of cleaning checklists for directing cleaning practices and reducing the environmental contamination.
... These studies have utilized a standardized metered transparent gel specifically formulated for the covert evaluation of healthcare surface cleaning. While nonstandardized fluorescent powders and lotions have been used in a non-covert manner for education [90], other studies [89,91] demonstrated that these substances visibility in ambient light limited their effective use in programs to objectively monitor cleaning practice as a result of their ability to induce a Hawthorne effect. In 2019 a study from Johns Hopkins compared the clinical use of the metered applicator with a standardized fluorescent gel to a cotton swab applicator with a non-standardized fluorescent gel and found that the metered applicator provided a more accurate assessment of cleaning practice. ...
As today’s most prevalent and costly healthcare-associated infection, hospital-onset Clostridioides difficile infection (HO-CDI) represents a major threat to patient safety world-wide. This review will discuss how new insights into the epidemiology of CDI have quantified the prevalence of C. difficile (CD) spore contamination of the patient-zone as well as the role of asymptomatically colonized patients who unavoidable contaminate their near and distant environments with resilient spores. Clarification of the epidemiology of CD in parallel with the development of a new generation of sporicidal agents which can be used on a daily basis without damaging surfaces, equipment, or the environment, led to the research discussed in this review. These advances underscore the potential for significantly mitigating HO-CDI when combined with ongoing programs for optimizing the thoroughness of cleaning as well as disinfection. The consequence of this paradigm-shift in environmental hygiene practice, particularly when combined with advances in hand hygiene practice, has the potential for significantly improving patient safety in hospitals globally by mitigating the acquisition of CD spores and, quite plausibly, other environmentally transmitted healthcare-associated pathogens.
... 8 Other investigators have used fluorescent powder or adenosine triphosphate (ATP) detection in a similar fashion. [26][27][28] Neither fluorescent gel, fluorescent powder, nor ATP removal measures disinfection. In our institution, all cleaning is performed with a cleaner-disinfectant combination, so we expect that surface disinfection will be accomplished by the cleaning process. ...
Objective
Short-term improvements in hospital room cleaning can readily be achieved but are difficult to maintain. This is particularly true for high-risk, “high-touch” surfaces. Therefore, we embarked on a process to sustain improvements in surface cleaning and disinfection to reduce hospital-acquired infection (HAI) rates.
Interventions
Our environmental services (EVS) and infection prevention departments incorporated a formal education, monitoring, and feedback process for focused cleaning and disinfection of high-touch surfaces into their routine policies and procedures in 2011. Cleaning validation was performed by infection prevention liaison nurses using a fluorescent targeting method to evaluate the thoroughness of cleaning.
Results
Surface cleaning performance on medical-surgical units in 2011 was 74.7%, but this rate incrementally increased in response to the interventions and has been sustained at >90% for the past 6 years. Similar patterns of improvement were observed in the operating room, labor and delivery, endoscopy suite and cardiac catheterization laboratory. Conversely, HAI rates, particularly C. difficile rates, decreased by 75% and surgical site infection rates decreased by 55%.
Conclusions
EVS training, monitoring, and feedback interventions, instituted 10 years ago have enhanced our environmental cleaning and disinfection efforts in multiple areas of the hospital and have been sustained to the present. Although other concurrent initiatives to reduce infection rates also existed, the improvements in environmental cleaning were associated with dramatic reductions in HAI rates over the 10-year period.
... So after cleaning, a considerable amount of organic soil can remain on surfaces, with the risk of growth and consequently spread of micro-organisms. 8 Various studies report different cut-off values for ATP measurements 9,10,11,12,13,14 , most of these cut-offs are intended for measurement directly after cleaning. However, the development of environmental contamination on hospital surfaces is unknown and the time until a supposed equilibrium is achieved during normal activities in combination with routine cleaning is still yet to be described. ...
Background
ATP measurement is frequently used to determine surface contamination in hospitals. Development of surface contamination in a new hospital building after entry into service is unknown. We aimed to evaluate the development of surface contamination in a new hospital setting.
Methods
Repeated ATP measurements were performed on 10 pre-defined fomites in eight patient rooms on two separate wards. Six rounds of ATP measurements with increasing time intervals were performed; another three rounds were performed directly after cleaning. Development of surface contamination over time was assessed. The lowest achievable RLU values were assessed by performing ATP measurements directly after cleaning.
Results
In total 580 ATP measurements were conducted. The first six rounds consisted of 480 ATP measurements. The three rounds after cleaning consisted of 100 ATP measurements. The median RLU value per round in chronological order was: 100, 396, 670, 273, 733, 351. The median RLU value per round after cleaning in chronological order was 226, 412, 226. Significant differences in median RLU values before and after opening of the new hospital were found and median RLU values directly after cleaning were significantly lower than in routine use.
Conclusions
Before commissioning of the new hospital, low surface contamination is found based on RLU values. An equilibrium in surface contamination is quickly achieved with substantial fluctuations in cleanliness between rounds of measurements.
... As part of an earlier study to compare various methods for assessing the adequacy and terminal cleaning procedures, 14 aerobic colony counts were performed on 5 high-touch surfaces in a convenience sample of patient rooms before and approximately 10-15 minutes after terminal cleaning and disinfection had been carried out by hospital housekeepers using a quaternary ammonium disinfectant (Virex II 256 Concentrate Disinfectant, Diversey, Fort Mill, SC), which contains the following active ingredients: N-alkyl dimethyl benzyl ammonium chloride (benzalkonium chloride) and didecyl dimethyl ammonium chloride. Aerobic colony counts were performed using D/E neutralizing agar contact plates (BD or Remel) to sample sites that included bedside rails, overbed tables, television remotes, bathroom grab bars, and toilet seats. ...
Background
: Microbiological monitoring of disinfection of high-touch surfaces identified heavy growth of Serratia marcescens and Achromobacter xylosoxidans not present on surfaces before disinfection, suggesting contamination of the disinfectant used.
Methods
: An investigation included interview of the housekeeper involved, level of bacterial contamination of the in-use quaternary ammonium (Quat) disinfectant, bactericidal activity of the contaminated disinfectant, pulsed field gel electrophoresis of S.marcescens and Achromobacter isolates, survival of S. marcescens on dry surfaces, and genome sequencing to identify possible Quat resistance genes.
Results
: The housekeeper, who seldom cleaned patient rooms, had used the disinfectant for months without emptying and drying the bucket between uses. The contaminated disinfectant contained 9.3 × 10⁴ CFU of S. marcescens plus A. xylosoxidans. The log10 reduction of S. marcescens by fresh Quat was 10²-fold lower than that achieved against a control strain (S. marcescens ATCC 13380). Genome sequencing of S. marcescens isolates identified the following genes previously shown to encode for efflux pumps associated with Quat resistance: sdeXY, sdeAB, smfY, and a sugE-like gene.
Conclusions
: Failure to follow existing guidelines and manufacturer's instructions for use resulted in contamination by A. xylosoxidans and by S. marcescens that possessed multiple genes associated with Quat resistance.
Floor cleaning and disinfection are essential components of maintaining animal health status and meeting regulatory requirements in research vivaria. However, best practices for method, frequency, and evaluation techniques have not been established. Reuse of cotton string mop and bucket systems has been implicated in spreading contamination in the human hospital setting. We evaluated 4 different combinations of disinfectant and mop systems commonly used in rodent vivaria. Eight housing rooms were mopped a total of 4 times using one of the following methods: quaternary ammonium compound (QUAT) and cotton string mop (QC), QUAT and microfiber mop (QM), hydrogen peroxide disinfectant (HPD) and cotton string mop (HC), or HPD and microfiber mop (HM). ATP and RODAC samples of the floor were taken before and after mopping. The time to mop each room, floor drying time, and the amount of disinfectant used were recorded. The QC method was associated with significantly more bacterial contamination while all other methods significantly reduced bacterial contamination. The QC method performed significantly worse in reducing bacterial contamination as compared with all other methods when cotton mop heads were reused. All methods except QC significantly reduced ATP levels, with the HC and HM methods being significantly more effective at reducing ATP levels than the QC and QM methods. Costs were similar for the QC, QM, and HM methods. The results of this study indicate that reuse of cotton string mop heads with QUAT increases floor contamination while HPD is effective for up to 3 reuses. Single use microfiber mops were effective with both QUAT and HPD but did not result in more effective cleaning or disinfection than cotton string mops.
Background:
The objective of this study was to determine if feedback of adenosine triphosphate (ATP) measurements decreases environmental contamination within hospitals in the Dutch/Belgian border area.
Methods:
Standardized ATP measurements were conducted in nine hospitals on pre-defined fomites. Four different fomite groups were defined: medical devices, patient bound materials, ward bound materials and sanitary items. ATP results were reported in relative light units (RLU), RLU >1000 was considered as "not clean." Two rounds of ATP measurements were conducted. After the first round of ATP measurements, results were provided to the wards and cleaning staff. The second round of ATP measurements was performed one year later. The amount of surface contamination before and after the feedback was compared.
Results:
In total 1923 ATP measurements were performed. Before feedback 960 ATP measurements were conducted and after feedback 963. The overall median reduction in RLU was 381 (P <0.001), from 568 before feedback to 187 afterwards. In each hospital there was a reduction of the median RLU after feedback.
Conclusion:
Substantial reductions in RLU values were found after feedback of ATP measurements. Feedback of ATP measurement in itself was associated with a major reduction of surface contamination in hospitals.
Recent research has significantly clarified the impact of optimizing patient-zone environmental hygiene. New insights into the environmental microbial epidemiology of many hospital-associated pathogens, especially Clostridioides difficile, have clarified and quantified the role of ongoing occult pathogen transmission from the near-patient environment. The recent development of safe, broadly effective surface chemical disinfectants has led to new opportunities to broadly enhance environmental hygiene in all health care settings. The Centers for Disease Control and Prevention has recently developed a detailed guidance to assist all health care settings in implementing optimized programs to mitigate health care-associated pathogen transmission from the near-patient surfaces.
Background
An algorithm has been improved to mitigate variability in cleanliness measurements of various surfaces using rapid Adenosine Triphosphate (ATP) testing. A cleaning intervention step (CIS) verifies the cleanability of those surfaces.
Methods
ATP testing was performed on surfaces which were pre-approved as “clean” and ready for re-use. Adjacent (duplicate) ATP sampling was undertaken on 421 environmental surfaces, medical devices and other implements. The CIS was conducted on 270 surfaces using an aseptic technique and disposable cleaning wipes.
Results
The two initial ATP results were plotted against each other with a 100 RLU threshold grading the results as clean (2x < 100RLU), dirty (2x > 100RLU) or equivocal (1x < 100RLU and 1x > 100RLU). Of the surfaces sampled, 68.5 % were clean (288/421), 13.5 % were dirty (57/421) and 18 % were equivocal (76/421). The duplicate testing demonstrated a false negative rate of 10 % (44/421) where the first swab was <100 RLU and the second swab >100 RLU. For the equivocal group, the gap between the two swabs was >100 RLU for 7.5 % of surfaces (33/421). The CIS was conducted on 270 of the surfaces tested and showed that cleaning could be improved (P=<0.001) on 88.5 % of surfaces (239/270).
Conclusion
The simplified ATP testing algorithm provides real-time discrimination between surface cleanliness levels and improved certainty over surface hygiene. The duplicate swab sampling approach mitigates uncontrolled variability in the results and the CIS provides a nuanced understanding of the measurable cleanliness of any surface.
This study evaluated three methods for monitoring hospital cleanliness. The aim was to find a benchmark that could indicate risk to patients from a contaminated environment. We performed visual monitoring, ATP bioluminescence and microbiological screening of five clinical surfaces before and after detergent-based cleaning on two wards over a four-week period. Five additional sites that were not featured in the routine domestic specification were also sampled. Measurements from all three methods were integrated and compared in order to choose appropriate levels for routine monitoring. We found that visual assessment did not reflect ATP values nor environmental contamination with microbial flora including Staphylococcus aureus and meticillin-resistant S. aureus (MRSA). There was a relationship between microbial growth categories and the proportion of ATP values exceeding a chosen benchmark but neither reliably predicted the presence of S. aureus or MRSA. ATP values were occasionally diverse. Detergent-based cleaning reduced levels of organic soil by 32% (95% confidence interval: 16-44%; P<0.001) but did not necessarily eliminate indicator staphylococci, some of which survived the cleaning process. An ATP benchmark value of 100 relative light units offered the closest correlation with microbial growth levels <2.5 cfu/cm(2) (receiver operating characteristic ROC curve sensitivity: 57%; specificity: 57%). In conclusion, microbiological and ATP monitoring confirmed environmental contamination, persistence of hospital pathogens and measured the effect on the environment from current cleaning practices. This study has provided provisional benchmarks to assist with future assessment of hospital cleanliness. Further work is required to refine practical sampling strategy and choice of benchmarks.
Prospective observations and adenosine triphosphate bioluminescence assays were used to evaluate daily cleaning practices in a university-affiliated hospital. Substantial variations were found in the amount of time spent cleaning high-touch surfaces, in the number of disinfectant wipes used in each room, and in the level of cleanliness achieved by housekeepers.
To evaluate the usefulness of an adenosine triphosphate (ATP) bioluminescence assay for assessing the efficacy of daily hospital cleaning practices.
A 2-phase prospective intervention study.
A university-affiliated community teaching hospital.
During phase I of our study, 5 high-touch surfaces in 20 patient rooms were sampled before and after daily cleaning. Moistened swabs were used to sample these surfaces and were then plated onto routine and selective media, and aerobic colony counts were determined after 48 hours of incubation. Specialized ATP swabs were used to sample the same high-touch surfaces in the 20 patient rooms and were then placed in luminometers, and the amount of ATP present was expressed as relative light units. During phase II of our study, after in-service housekeeper educational sessions were given, the housekeepers were told in advance when ATP readings would be taken before and after cleaning.
During phase I, the colony counts revealed that the 5 high-touch surfaces were often not cleaned adequately. After cleaning, 24 (24%) of the 100 surface samples were still contaminated with methicillin-resistant Staphylococcus aureus, and 16 (16%) of the 100 surface samples still yielded vancomycin-resistant enterococci. ATP readings (expressed as relative light units) revealed that only bathroom grab bars and toilet seats were significantly cleaner after daily cleaning than before. During phase II, a total of 1,013 ATP readings were obtained before and after daily cleaning in 105 rooms. The median relative light unit was significantly lower (ie, surfaces were cleaner) after cleaning than before cleaning for all 5 high-touch surfaces.
Suboptimal cleaning practices were documented by determining aerobic colony counts and by use of an ATP bioluminescence assay. ATP readings provided quantitative evidence of improved cleanliness of high-touch surfaces after the implementation of an intervention program.
Objective: To study the possible role of contaminated environmental surfaces as a reservoir of methicillin-resistant Staphylococcus aureus (MRSA) in hospitals. Design: A prospective culture survey of inanimate objects in the rooms of patients with MRSA. Setting: A 200-bed university-affiliated teaching hospital. Patients: Thirty-eight consecutive patients colonized or infected with MRSA. Patients represented endemic MRSA cases. Results: Ninety-six (27%) of 350 surfaces sampled in the rooms of affected patients were contaminated with MRSA When patients had MRSA in a wound or urine, 36% of surfaces were contaminated. In contrast, when MRSA was isolated from other body sites, only 6% of surfaces were contaminated (odds ratio, 8.8; 95% confidence interval, 3.7-25.5; P
Background: Clostridium difficile spores may persist in the hospital environment for extended periods of time. The purpose of the study was to evaluate whether admission to a room previously occupied by a patient with CDAD increased a patient’s risk of acquiring CDAD. Methods: A retrospective cohort of patients admitted to the medical intensive care unit (ICU) between 1/1/05 to 6/30/06 was evaluated. Medical records, microbiology records, and infection control records were used to identify CDAD cases. CDAD was considered hospital-acquired if diagnosis was after 48 hours of admission or within 30 days of discharge from the unit. CDAD patients were considered capable of environmental contamination up to 30 days after diagnosis. Medical records were reviewed for other risk factors for CDAD acquisition. Statistical analysis was completed using Chi squared test, Kaplan-Meier survival and cox proportional hazards models. Results: Of 1844 ICU admissions, 136 CDAD cases were identified. 47 patients had CDAD infection prior to or at the time of ICU admission. Of the remaining 1797 admissions, 1685 patients had a prior occupant without CDAD, 91 had a prior occupant with CDAD, and 89 (4.95%) acquired CDAD within 30 days of room occupation. Of the 89 CDAD patients, 79 out of 1685 (4.69%) had a prior occupant with no CDAD, while 10 out of 91 (11%) had a prior occupant with CDAD (p=0.002). Effect of prior occupant’s CDAD status remained significant (p = 0.0432) when controlling for the current patient’s age and Acute Physiology and Chronic Health Evaluation (APACHE) III score. Further analysis to control for antibiotic and proton pump inhibitor use is ongoing. Conclusions: These results suggest that a prior room occupant with CDAD is a significant risk for CDAD acquisition, independent of age and APACHE III score. These findings have future implications for room placement and room cleaning practices.
Background: VRE and MRSA can contaminate environmental surfaces and persist for months despite routine cleaning, which may contribute to transmission. Novel techniques, including HPV decontamination, a sporicidal, vapor phase method to decontaminate enclosed areas/equipment, are of interest. Methods: Between 08/07 and 06/08, monthly environmental cultures for VRE and MRSA were performed in all patient rooms on 5 high-risk units. Between 12/07 and 6/08, HPV decontamination was performed on rooms of patients known to be colonized or infected with resistant organisms (VRE, MRSA, resistant gram negatives and C. difficile) at time of discharge in 3 of these units. Adherence to HPV decontamination was recorded. Changes in rates of patient acquisition of VRE and MRSA per 100 at risk patients were compared pre and post HPV implementation and compared with changes in rates in the same time period in the 2 units using standard environmental cleaning. Results: Environmental contamination with resistant organisms was reduced by 37% in intervention units (13% of 397 vs. 21% of 171, p=0.02) but was unchanged in non-intervention units (28% of 317 vs. 24% of 157, p=0.32). The reduction in the odds of patient acquisition of VRE in the units employing HPV was 35% greater than the reduction in odds of acquisition in control units (OR 0.65, 95% CI 0.37-1.15, p=0.13). There was no significant change in MRSA acquisition (p= 0.30) in intervention units compared with control units. However, adherence to HPV decontamination varied among intervention units. Better adherence with HPV decontamination reduced incidence rates of VRE acquisition. For every 1% increase in adherence with HPV decontamination there was a 3% reduction in VRE incidence (IRR 0.97, p=0.01). Conclusions: HPV decontamination decreases environmental contamination and reduces VRE transmission in high-risk units but adherence to routine use of HPV is key to maximizing the benefits of the technology.
A total environmental cleaning system based on microfiber technology was implemented within 2 intensive care units (ICUs). The efficacy of this modified cleaning program was assessed using adenosine triphosphate (ATP) bioluminescence.
A team of trained hygiene technicians cleaned all near-patient furniture and equipment twice a day using ultramicrofiber cloths. Every week for 40 weeks, 10 surfaces within a randomly selected bed area were sampled using the 3M Clean-Trace Clinical Hygiene Monitoring System (3M Health Care Ltd, Loughborough, United Kingdom). The ability of the modified cleaning program to reduce surface contamination to "acceptable" levels was measured against previously proposed benchmark ATP values.
In comparison with normal cleaning procedures routinely carried out by the nurses, the modified cleaning program significantly reduced (P < .001) the ATP readings obtained from surfaces within the near-patient environment. In both ICUs, 95% of surfaces sampled after modified cleaning had relative light unit values of <500 and were deemed "clean." Almost 90% of the surfaces could also be "passed" using the more stringent benchmark value of 250 relative light units. However, regardless of benchmark value used, the majority of surfaces sampled could also be considered adequately clean prior to them being cleaned by the hygiene technicians.
The use of ATP bioluminescence has been proposed as a means to improve the management of hospital cleaning. Use of benchmark values can help continually monitor the efficacy of existing cleaning programs. However, when evaluating novel or new cleaning practices, baseline cleanliness (ie, the level of cleanliness routinely achieved using normal cleaning procedures) must also be taken into consideration, or the efficacy of modified cleaning will be overestimated.
An important component of effective cleaning in hospitals involves monitoring the efficacy of the methods used. Generally the recommended tool for monitoring cleaning efficacy is visual assessments. In this study four methods to determine cleaning efficacy of hospital surfaces were compared, namely visual assessment, chemical (ATP) and microbiological methods, i.e. aerobic colony count (ACC) and the presence of meticillin-resistant Staphylococcus aureus. Respectively, 93.3%, 71.5%, 92.1% and 95.0% of visual, ATP, ACC and MRSA assessments were considered acceptable or 'clean' according to each test standard. Visual assessment alone did not always provide a meaningful measure of surface cleanliness or cleaning efficacy. The average ATP value from 120 swabs before cleaning was 612 relative light units (RLU) (range: 72-2575) and 375 RLU after cleaning (range: 106-1071); the accepted standard is 500 RLU. In a hospital setting with low microbiological counts, the use of chemical tests such as ATP may provide additional information of cleaning efficacy and ATP trends allow identification of environmental surfaces that require additional cleaning or cleaning schedule amendments.
A quantitative ATP bioluminescence procedure has been used to determine the cleanliness of food processing factories and the results have been compared with those from conventional microbiological culture methods. ATP measurements were combined with the tissue or tissue fluid contamination (TTFC) assessment method to obtain an impression of the amount of inanimate contamination on the sampled surfaces. It was found that, in the sampled food factories, there was poor relation between the two assessment techniques: ATP bio-luminescence combined with TTFC and contact plating. However, either method in its own right is useful to check cleanliness of food industries. ATP measurements do have in addition the great advantage that it is a fast method and is easy to perform.