AIM OF THE TRIAL
1. The aim of the trial was to assess in a clinical
setting, whether the anti bacterial efficacy of the product D-Stroy/Activ8
warranted further investment in the planned comprehensive clinical
trials programme. The specific objectives were to evaluate:
a. The effect of D-Stroy/Activ8 on environmental contamination:
i. Qualitatively by the number of swabs showing
a significant reduction one hour after cleaning, and
ii. Quantitatively by measuring the magnitude
of the reduction found.
b. The residual antimicrobial effect of the
cleaning agents on the test areas during a period of 24 hours
between treatments when further contamination took place.
c. The one-hour and residual 24-hour effects
of D-Stroy/Activ8 and two commercially available cleaning agents (Daily
Washroom Cleaner with/without ethanol, and Professional Fairy
Liquid with ethanol) on microbial contamination.
d. A proposed standardised methodology to assess
the degree of disinfection.
CONDUCT
AND ANALYSIS FROM THE TRIAL
2. The trial was conducted and independently
analysed by the Health Protection Agency South West (HPA SW) Regional
Laboratory.
MAIN CONCLUSIONS FROM THE TRIAL
3. It is concluded that:
a. Overall, the reduction in bacterial count by D-Stroy/Activ8
was consistently over 80%. This is a remarkable result in the
context of a field trial in heavily contaminated areas that were
continuously in use.
b. When qualitative reductions (a minimum 1 log)
were measured against comparator products, D-Stroy/Activ8 achieved a:
i. Greater number of significant reductions
in bacterial load.
ii. A significant overall difference of p=0.03.
c. When quantitative reductions were measured:
i. D-Stroy/Activ8 achieved a significant reduction
of 87% in the total bacterial load compared with 65%(p=0.002)
and log reductions (p=0.038) for the combined results of comparators.
ii. In separate evaluations, similar reductions
were 87%, 91% and 83% for D-Stroy/Activ8 and 79%, 70% and 47%
for the comparators (p=0.32, 0.07 and 0.02 respectively) with
greater reductions in bacterial load when environmental contamination
was high.
d. Despite reductions in bacterial loads after
cleaning, the counts quickly recovered to previous levels suggesting
cleaning has a relatively short term effect.
e. Despite differences between the three products,
the comparability of data sets indicates that the experimental
approach was valid.
f. While the reduction in total aerobic bacterial
load (ACC) was significantly greater with D-Stroy/Activ8, no significant
differences were seen when data was analysed for individual Indicator
Organisms.
g. Although the dataset is too small to substantiate
comment on any selective effect of D-Stroy/Activ8 on these Indicator
Organisms, the data does indicate that cleaning with D-Stroy/Activ8
was associated with more reductions of >1Log, and fewer reductions
of <1 Log, than with the other cleaners.
RECOMMENDATIONS
4. It is therefore recommended that the Management
Board of Greenbridge Environmental Control Limited:
a. Notes the results and conclusions of the trial.
b. Continues with its plans for a coordinated
trials programme to provide the robust scientific evidence it
requires for commercial purposes.
MAIN SUMMARY
• This report on D-Stroy/Activ8 is the first evaluation
undertaken in a clinical setting. The study was completed over
a three-week period, to establish suitable methods for the evaluation
of disinfectants in this setting and in particular to assess the
properties of this composite cleaning and disinfecting solution.
• Qualitative and Quantitative Methodologies were developed
for testing these cleaning agents with disinfectant properties,
with respect to experimental design and statistical analysis.
• The study methodology was designed as a preliminary evaluation
of D-Stroy/Activ8, to inform Greenbridge Environmental Control
Ltd of the ‘potential’ of the product in conditions
of ‘normal use’, and as such, was not powered to answer
all the questions that may legitimately be asked of a cleaning
and disinfecting agent used in infection control practice.
• A comparison of reductions in environmental contamination
after cleaning with D-Stroy/Activ8 and other commercially available
cleaning agents (a general purpose detergent [Daily Washroom Cleaner]
in week one, a detergent and antibacterial composite cleaner [Professional
Fairy Liquid] supplemented with 70% ethanol (Klercide) in week
2 and Daily Washroom Cleaner supplemented with 70% ethanol in
week 3), was made for both total aerobic colony count and quantitative
counts for individual indicator organisms normally found in the
clinical setting.
• The percentage reduction of the bacterial load (total
ACC) seen after cleaning with D-Stroy/Activ8 was consistently
over 80% in all three weeks, and greater than that seen after
cleaning with the other agents used during the 3 week study. In
week 1-3, the reductions were 87%, 91% and 83% for D-Stroy/Activ8
respectively, for a variety of clinical areas with differing levels
of contamination, compared to 79% for Daily Washroom Cleaner in
week 1, 70% for Professional Fairy with Ethanol in week 2, and
47% for Daily Washroom Cleaner with Ethanol in week 3, for side
by side comparative areas, swabbed simultaneously before and after
cleaning.
• Statistically significant higher levels of disinfection
were achieved when D-Stroy/Activ8 (87% reduction) was used, compared
to the combined results for the other commercially available cleaning
agents used in the study (65% reduction).
• The percentage and log reductions seen were particularly
meaningful, as this study was a severe test, performed in a ‘real-life’
setting, rather than under laboratory conditions that could more
realistically compare potency but could not truly represent clinical
conditions, efficacy on the bacterial diversity and degree of
organic soiling.
• At higher levels of contamination reductions in bacterial
load were more readily demonstrable than at lower levels of contamination
for all cleaning agents. This effect was more pronounced with
D-Stroy/Activ8 than with the other cleaning agents. These results
imply that when used in heavily contaminated clinical areas, D-Stroy/Activ8
is likely to perform well.
• There was some evidence of a cumulative benefit on the
reduction of bacterial numbers, following repeated cleaning, when
either D-Stroy/Activ8 or the other cleaning agents were used.
There was a reduction in the overall level of contamination after
cleaning on a daily basis and over time, although it was evident
that areas became re-contaminated before re-cleaning the following
day, as would be expected in heavily used areas.
• The degree of contamination found in each area before
swabbing and the degree of re-contamination found before re-swabbing
indicated that the experimental approach was valid and areas comparable.
• The study examined the effect of D-Stroy/Activ8, and the
other cleaning agents, on the bacterial load of selected indicator
organisms present in clinical environments. No significant differences
were seen in this small data set. However, more reductions at
a level above 90% and fewer reductions at a level less than 90%
were seen in the dataset for Indicator Organisms for D-Stroy/Activ8
treated areas, than were seen when the other cleaning agents were
used.
• This study developed a methodology that was validated
during the course of the study. It is now important to see whether
these results are repeatable in other clinical settings so that
they might more directly inform infection control decision-making
for clinical areas where particular organisms are seen to be a
problem.
• We believe that D-Stroy/Activ8 can be used as an effective alternative
to other cleaning agents for hard surface disinfection already
in use in clinical practice.
Authors at the Health Protection Agency, South West Regional
Laboratory, Bristol, BS2 8EL:
Dr David Carrington - BSc MBBS, DTM&H, FRCPath, PG
Cert (PH)
Consultant Medical Virologist, Head of Virology; Specialist Virology
Centre South West, Project Director, responsible for study design,
results analysis and interpretation.
Dr Peter Muir - BSc, PhD, Dip RCPath,
Head of Virology R&D; Specialist Virology Centre South West,
Contributed to data analysis and result interpretation
Maria Loughborough – BSc
Senior Scientist; Food, Water and Environment Laboratory, responsible
for sample processing, and contributed to design of laboratory
methods.
Acknowledgements:
Technical staff of the Food, Water and Environmental Laboratory,
of the HPA SW Regional Laboratory for undertaking the bacteriological
examination of the swab samples obtained.
Kevin Mitchell, of –‘Industrial Support’ an independent
healthcare contract cleaner who undertook the swabbing, cleaning
and re-swabbing of the clinical areas under investigation.
Greenbridge Environmental Control Ltd, for supplying the D-Stroy/Activ8
solution for evaluation.
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