Monitoring Hospital Cleanliness with Standardised ATP Measurements
Denmark introduces official guidelines for Adenosine-Triphosphate (ATP) tests
Dennis Andersen (Andersen Control Aps) Denmark
Aims
Table 1
To make a guideline to the Danish Standard for cleaning in the health care sector EN/DS 245110[1] that combines the visual control with a quantitative measuring method for the nonvisible
contamination- and transmission risk.
Introduction and background
The DS 2451-10 standard describes requirements for cleaning with a view to preventing
infections. These requirements build on scientific documentation or broad consensus based on the
experience of specialists in the fields of cleaning and infection prevention in the health care sector.
•International studies show there is a connection between resources for cleaning and acquired
infections in the health care sector. This should influence the resource allocation priorities for
cleaning [2][3][4]. With this standard, it will be possible to establish levels for the cleanliness of
surfaces and to obtain recommendations for work processes leading to the achievement of the
established hygiene levels. Levels and work processes for cleaning and quality control contributes
to eliminating infectious matter, thus helping to prevent infections.
•The transmission risk inherent in what is not related to spillage, and which is therefore not visible,
has been a matter of great interest to the working group with a view to finding reliable and
approved methods to map out risks and provide guidance on these risks. From visual inspection,
the possibilities of inspecting infection hygiene have moved via biological inspection to
microbiological inspection. The standard includes a biological inspection method, Adenosine
Triphosphate (ATP), as well as microbiological inspection methods, dip slide or contact plates.
Methods
The inspection method for ATP has been included as an informative annex (annex D in the
standard) due to the fact that, at the date of publication of the standard (2011), there was not
sufficient experience in the health care sector with using this method. The reason it has
nevertheless been included is the desire to contribute tools enabling a future framework for
collecting data which may shed light on the relationship between a not visible contamination and
transmission risk and thus to be able to determine sufficient cleaning methods and the need for
resources for cleaning.
The fields of application are the 10 critical risk points, in the literature named hand-touch sites[5],
lighting near the patient, patient rest, hand sink and water tap, screens, other sanitation, grips,
tables, stands, technical installations near the patient and other technical installations. The
probability for presence of infectious matter and the relevant critical risk points for each type of
room is stated in the annex A in the standard. There are in total five hygiene levels, but only the
three top levels (5,4,3) are relevant for quantitative measure, since there are no patients present in
the two lowest levels (1,2). Level 5 is care/treatment areas and production areas requiring a
particularly high degree of cleanliness. Level 4 and 3 are primarily patient-related areas.
To secure that the limit values where achievable, a small-scale study was performed at the
Aarhus University Hospital, Skejby at two following days in the same wardroom (Y2, 220). ATP
levels were determined using ‘Cleantrace’ swabs and a Uni-Lite NG luminometer (Biotrace
International Ltd, Bridgend, UK) over an area of 100 cm2 in a close zigzag pattern using the
manufacturer’s guidelines and expressed as relative light units (RLU) with a conversion factor of 1
femtomol ATP to 10 RLU. 50 time laundered Viima® Glass cloths from ‘De Forenede
Dampvaskerier A/S’ was used for cleaning. The special construction of 50% polyester and 50%
polyamide, 16 piece split fibre in the cloth has given the cloth ability to in vitro tests (EN 13697) to
reduce e.g. the log count from log7 to Log1 for staphylococcus aureus. It was therefore expected a
similar high reduction in ATP amount. Results are presented in table 1.
In following studies the ‘Ultrasnap’ swabs and a SystemSURE Plus luminometer (Hygiena
International Ltd, Watford, UK) were used. This system has a conversion factor of 1 femtomol ATP
to 1 RLU, which means the RLU scale corresponds to the amount of femtomol ATP (results not
shown).
OBJECT
BEFORE
CLEANING
AFTER CLEANING
Table by sink
Door handle
wardroom
Bed lamp
Bedside table
(305-258-351)
(49-16-81)
(1600-831-2369)
(19-13-24)
(327-233-421)
(293-193-393)
(23-10-36)
(27-13-41)
Wall rail
(1489-330-3648)
(34-17-50)
Tap handle
Total average
(461-79-842)
746
(157-44-269)
51
Sample size (n)
13
12
Table 2 shows the ATP level[6] for the stated hygiene levels at the critical risk points, expressed in
femtomole. Femtomole is often converted into RLU (Relative Light Unit). The conversion factor
depends on the measurement equipment. The Femtomole limit values are the results of the
proposed values in the literature of 500 and 250 RLU, divided with 10 since the ATP equipment in
the studies has a conversion factor of 1 to 10. [7][8]
Using a luminometer of which the scale of RLU corresponds to the amount of femtomol
eliminates the need for conversion.
Table 2, femtomol ATP limit values
Critical risk points
Hygiene level 5
Hygiene level 4&3
Light near patient
<25
<50
Patient rest
<25
<50
Hand sink & water tap
<25
<50
Screen
<25
<50
Other sanitary items
<25
<50
Grips
<25
<50
Tables
<25
<50
Stands
<25
<50
Technical installations near patient
<25
<50
Other technical installations
<25
<50
In case a result between 25 and 50 femtomol is obtained at a Hygiene 5 level location, this
requires further observation. A result above 50 femtomol requires intervention.
In case a result between 50 and 100 femtomol is obtained at a Hygiene level 4 and 3, this
requires further observation. A result above 100 femtomol requires intervention.
Example:
A wardroom, which is hygiene level 3, has the limit of 50 femtomol in each critical risk point.
Finding result in e.g. a hand sink higher than 50, means that you should observe and see if
further measuring indicates that cleaning is out of control. Results higher than 100 means that
you have to make a cause analysis to correct and prevent the error if possible.
Discussion and conclusion
Results
The small-scale study in table 1 shows that it is possible to achieve a significant reduction in
the RLU value, by using ultra effective micro fibre without detergent or disinfectant, but just
water. It was therefore according to reduction in figure 1 concluded to state the limit values as
reachable as presented in the literature.
The maximum level for ATP should according to previous proposal[7][8][9] not exceed 500 or 250
RLU per 100 cm2. However studies[10] show that the limits should be investigated. The standard
proposes the cleanliness levels according to table 2 knowing that there can be challenges to reach
these limits for certain types of surfaces and materials[11][12]. However the small-scale study in
table 1 show that the impact of ultra efficient cleaning methods can perform even lower ATP
amount after cleaning. The question is no longer if there should be a limited value for ATP, since it
has been proved a valid method to evaluate cleaning methods and resources needed for sufficient
results[13], but rather how it is possible to secure satisfying results on different materials and
surfaces using correct cleaning methods.
References
[1] EN/DS 2451-10:2014
[2] Dancer SJ, White LF, Lamb J, Girvan EK, Robertson C. Measuring the effect of enhanced cleaning in a UK hospital: a prospective cross-over study. BMC.Med. 2009;7:28.
[3] Hayden MK, Bonten MJ, Blom DW, Lyle EA, van de Vijver DA, Weinstein RA. Reduction in acquisition of vancomycinresistant enterococcus after enforcement of routine
environmental cleaning measures. Clin.Infect.Dis. 2006;42(11):1552-60.
[4] Mayfield JL, Leet T, Miller J, Mundy LM. Environmental control to reduce transmission of Clostridium difficile. Clin.Infect.Dis. 2000;31(4):995-1000.
[5] Dancer et al, BMC Medicine, 2009
[6] Boyce JM, Havill NL, Dumigan DG, Golebiewski M, Balogun O, Rizvani R. Monitoring the effectiveness of hospital cleaning practices by use of an adenosine triphosphate
bioluminescence assay. Infect.Control Hosp.Epidemiol. 2009;30(7):678-84.
[7] Griffith et al Journal of Hospital Infection (2000) 45:19–28
[8] Lewis, Griffith, Gallo, Weinbren, Journal of Hospital Infection (2008) 69, 156-163
[9] Am Journal of Infection Control 2003;31:93-6.
[10] Willis et al, Journal of Infection Prevention November 2007 vol. 8 no. 5 17-21
[11] Weber et al, Role of hospital surfaces in the transmission of emerging health care associated pathogens: Norovirus, Clostridium difficile, and Acinetobacter species. Am
Journal of Infection Control June 2010
[12] Brown E, Eder AR, Thompson KM. Do surface and cleaning chemistries interfere with ATP measurement systems for monitoring patient room hygiene? J Hosp. Infect
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[13] Mulvey et al, Finding a benchmark for monitoring hospital cleanliness, J Hosp. Infect (2011) 25-30