Healthcare Hygiene magazine October 2019 | Page 26

Carling (2013) adds, “Because approximately 60 percent
of patients zone surfaces have low or no viable aerobic
organisms on them, to use a monitoring tool that evaluates
cleanliness, it is necessary to determine whether the object
was clean before the monitored cleaning intervention took
place. Although somewhat logistically cumbersome, clean-
ing practice can be evaluated by a system that measures
cleanliness if objects with pre-existing very low bioburden or
organic matter are eliminated from the evaluation process.”
Upsetting the Apple Cart of “Clean”
In their study of applying the suggested ACC standards
to monitor environmental contamination, UK researchers
Cloutman-Green, et al. (2019) say the data demonstrate
that a large proportion of sites screened for bacterial
contamination would fail if using the criteria suggested
by other researchers —particularly those sites closest to
patients—suggesting that a new standard might be required.
Cloutman-Green, et al. (2019) point to a lack of govern-
ment guidance regarding acceptable numbers of microor-
ganisms on hospital surfaces: “Griffith, et al. suggested a
site should fail screening and be subject to investigation
if it has an ACC > 2.5 CFU/cm2 on an agar contact plate
(60 CFU/plate). This cutoff was based on food preparation
standards and has been adopted by others. Dancer pro-
posed the cutoff limit of 5 CFU/cm2 (120 CFU/plate) based
on U.S. Department of Agriculture limits of bacteria on
food-processing equipment, with failures leading to bed
space closures and repeat cleaning. Dancer and others have
since published articles using the lower cutoff limit of 2.5
CFU/cm2, referring to it as a ‘standard.’”
The researchers’ study applied the suggested ACC stan-
dards put forth by Griffith and Dancer for environmental
monitoring to wards and outpatient settings at a UK hos-
pital over 18 months to determine their suitability as part
of routine infection control monitoring. A total of 1,986
samples were taken at the same time each day, a minimum
of two hours after cleaning (within the pediatric hospital
with chlorine dioxide and in the adult units with water and
microfiber towels; other cleaning was undertaken using
alcohol wipes by nursing staff.) Samples were taken from
fixed surface sites of differing heights, touch frequencies,
and materials and included bed rails and areas that were
expected to have high levels of contamination such as the
floor and bed wheels. ACC sampling was carried out and
CFUs were analyzed by the criteria proposed by Griffith and
Dancer, and sites failed screening if they had counts above
these suggested limits.
Cloutman-Green, et al. (2019) report that when using
the suggested standard of 2.5 CFU/cm, 93 percent of bed
spaces and 32 percent of sites sampled failed screening.
Using the suggested standard of 5 CFU/cm, more than half
of bed spaces (66 percent) would have needed to be closed
and recleaned and 15 percent of sites would have failed.
Results were similar across ward types using the 120 CFU
standard, with a range of 9 percent to 27 percent; how-
ever, a broader range of failures occurred with the 60 CFU
standard (28 percent to 55 percent). Colony counts for bed
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spaces were similar for the 60 CFU standard with a range
of 80 percent to 100 percent failing screening. Using the
120 CFU standard, the range was broader for bed spaces,
with between 50 percent and 83 percent failing screening.
Cloutman-Green, et al. (2019) conclude that, “Our data
demonstrate that in a dynamic hospital environment, a large
proportion of sites screened for bacterial contamination
would fail if using the criteria suggested by previous authors,
particularly those sites closest to patients. This could lead to the
closure of wards or bed spaces, increased costs, and decreased
patient care. Surfaces are frequently contaminated even with
routine cleaning and no reported cases of bacterial HAI on
the pediatric wards during the monitoring period; therefore,
the levels proposed by Griffith and Dancer are not practical
to maintain. ACCs are clearly helpful, particularly in research
settings where standardization is critical. However, for routine
environmental monitoring, the proposed standards may lead
to considerable disruption in the absence of a direct correlation
with transmission of HAI. We suggest a move away from
using ACC for determining microbiology standards in hospital
environments and instead advocate monitoring for indicator
organisms such as methicillin-resistant Staphylococcus aureus
and carbapenemase-resistant Enterobacteriaceae.”
What Hospitals Can Do in the Absence of a
Definitive Standard
Without definitive standards for defining cleanliness,
infection preventionists and environmental services directors
must evaluate the literature as well as the current chemistries
and technologies in the marketplace to determine a plan of
action for their institutions.
Despite efforts over the past 15 years, it has been extremely
challenging to pinpoint a system that definitively defines the
clinical relevance of the healthcare surface. As Carling says,
“There had been some hope for 2.5 CFU/cm2 as being a
standard, yet there is no scientific evidence of the relevance
of such a value. The problem is that bioburden on either
cleaned or uncleaned surfaces is very low, and it has been
difficult to develop a reproducible single value system with
enough sensitivity and specificity to measure such a value
accurately. Furthermore, reproducibly evaluating small and
irregular objects adds to the challenge. The other point besides
the fact that bioburden is low, is that for the pathogens we
worry about, every one of them has a low infective dose.
So just because a surface has a low level of bioburden, and
you don’t find MRSA on that one little slide you just took off
the surface doesn’t mean it’s not right next to it. The same
goes for other pathogens such as norovirus and C. difficile.”
Only one thing is for certain right now — that the lively
dialogue over defining a standard of cleanliness — and
whether to use the 2.5 CFU/cm2 standard — continues. As
noted in the commentary by Carling and Huang, “Improving
Healthcare Environmental Cleaning and Disinfection: Current
and Evolving Issues” in Infection Control and Hospital Epi-
demiology (2013), “Since the realistic goal of environmental
cleaning and disinfection of patient-care areas is not to
produce a continuously sterile surface environment but rather
to effectively decrease pathogen transmission, multi-center
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