Alfa MJ, Degagne P, Olson N. Worst-case soiling levels for patient used
flexible endoscopes before and after cleaning. Am J Infect Control
1999;27:392-401.
Worst-case soiling levels for patient-used flexible endoscopes before and
after cleaning
BACKGROUND: The soiling levels of patient-used narrow-lumened flexible
endoscopes were assessed for bronchoscopes, duodenoscopes, and colonoscopes.
The effect of cleaning on the soil composition and concentration was
evaluated. DESIGN: Suction channels from 10 each of bronchoscopes,
duodenoscopes used for endoscopic retrograde cholangiopancreatography, and
colonoscopes were assessed immediately after patient use for the levels of
bilirubin, hemoglobin, protein, sodium ion, carbohydrate, endotoxin, and
viable bacteria. Another 10 suction channels of each type of endoscope were
evaluated for the same components after routine cleaning but before
processing by high-level disinfection or sterilization for subsequent
clinical use. RESULTS: Recognizing that only soluble components could be
quantified, the worst-case soil levels in the suction channels (the average
surface area of these channels was 45.6 cm(2), 149.8 cm,(2) and 192.0 cm(2)
for bronchoscopes, duodenoscopes, and colonoscopes, respectively) were
protein 115 microg/cm(2), sodium ion 7.4 micromol/cm(2), hemoglobin 85
microg/cm(2), bilirubin 299 nmol/cm(2), carbohydrate 29.1 microg/cm(2),
endotoxin 9852 endotoxin units/cm(2), and bacteria 7.1 (log(10))
colony-forming units (CFU)/cm(2). Colonoscopes had 4 to 5 times greater
soiling on average compared with the other endoscope types. Routine cleaning
reduced the levels of bilirubin to below the limits of detection for all
endoscopes evaluated (limits of detection were <1 nmol/mL). After cleaning,
residual hemoglobin was detectable in bronchoscopes only. After cleaning,
the levels of protein, endotoxin, and sodium ion all were reduced fivefold
to tenfold for all types of endoscopes. Carbohydrate was reduced to lower
than the limit of detection for all endoscopes after cleaning, except the
duodenoscopes. The average load of viable bacteria was reduced from 3
log(10) to 5 log(10) CFU/cm(2) (which represents 5.9-9.5 log(10)
CFU/endoscope channel) after patient use to approximately 2 log(10)
CFU/cm(2) (which represents 3.2-5.3 log(10) CFU/endoscope channel) after
cleaning. CONCLUSIONS: These data demonstrated that cleaning effectively
reduced or eliminated many components of soil, but a substantial amount of
viable bacteria and protein remained. Hemoglobin levels in before samples
indicated that blood was not present in high concentrations in the suction
channels of the majority of flexible endoscope samples. Soil that mimics the
worst-case composition from patient-used endoscopes would be ideal for
simulated-use studies for such medical devices.
Manual Methods Are Suboptimal Compared With Automated Methods for Cleaning
of Single-Use Biopsy Forceps M. J. Alfa, PhD; R. Nemes, MD; N. Olson, BSc;
A. Mulaire, BSc
objective. Most reusable biopsy forceps and all of the currently available
single-use biopsy forceps do not have a port that allows fluid flow down the
inner tubular shaft of the device. Reusable biopsy forceps are widely used
and reprocessed in healthcare facilities, and singleuse biopsy forceps are
reprocessed either in-house (eg, in Canada and Japan) or by third-party
reprocessors (eg, in the United States). The objective of this study was to
determine the cleaning efficacy of automated narrow-lumen sonic irrigation
cleaning, sonication-only cleaning, and manual cleaning for biopsy forceps.
design. A simulated-use study was performed by inoculating the inner channel
of single-use biopsy forceps with artificial test soil containing both
Enterococcus faecalis and Geobacillus stearothermophilus at concentrations
of 106 colony-forming units per milliliter. The cleaning methods evaluated
were manual cleaning, sonication-only cleaning, and “retroflush” cleaning by
an automated narrow-lumen irrigator. Bioburden and organic soil reduction
after washing was evaluated. Forceps used in biopsies of patients were also
tested to determine the worst-case soiling levels.
results. Only retroflush irrigation cleaning could effectively remove
material from within the shaft portion of the biopsy forceps: it achieved an
average reduction of more than 95% in levels of protein, hemoglobin,
carbohydrate, and endotoxin. However, even this method of cleaning was not
totally effective, as only a 2 log10 reduction in bioburden could be
achieved, and there were low residual levels of hemoglobin and carbohydrate.
conclusion. The data from this evaluation indicate that manual and
sonication-only cleaning methods for biopsy forceps were totally ineffective
in removing material from within the biopsy forceps. Even the use of
retroflush cleaning was not totally effective. These findings suggest that
in-hospital reprocessing of biopsy forceps with currently available
equipment and cleaning methods is suboptimal.
Infect Control Hosp Epidemiol 2006; 27:841-846
A new hydrogen peroxide–based medical-device detergent with germicidal
properties: Comparison with enzymatic cleaners
Background: The objective of this study was to evaluate the efficacy of
the cleaning and bacterial killing ability of a new non–enzyme-based
formulation (killing detergent solution [KDS]) compared with
commercially available enzymatic detergents that included Metrizyme (Metrex
Research Division of Sybron Canada Ltd. Morrisburg, Ontario) and Gzyme (Germiphene
Corp, Brantford, Ontario). KDS is a hydrogen peroxide–based detergent
formulation that combines cleaning efficacy with the ability to kill
microorganisms. The KDS formulation helps ensure the protection of the
health care worker from infectious risk during the soaking and cleaning
stages of medical device reprocessing and reduces the bioburden on
devices before sterilization/disinfection. Methods: Test organisms that
included Enterococcus faecalis, Salmonella choleraesuis, Staphylococcus
aureus, and Pseudomonas aeruginosa were suspended in artificial test
soil (ATS-B; patent submitted), inoculated at 106 colonyforming units
per carrier and dried overnight before detergent exposure. The ATS-B
mimics the blood, protein, carbohydrate, and endotoxin levels of
patient-used medical devices. Plastic lumen carriers and a flexible
colonoscope were used for surface and simulated-use testing,
respectively. Results: The results for the microbial challenge dried
onto polyvinyl chloride (PVC) carriers demonstrated that the ability of
KDS to remove protein, blood, carbohydrate, and endotoxin from surface
test carriers was as effective as the enzyme detergents that were
evaluated. Furthermore, KDS was able to effect approximately a 5-Log10
reduction in microbial loads with a 3-minute exposure at room
temperature, whereas none of the other detergents were as effective. In
simulated-use testing of a soiled colonoscope, KDS was significantly
better at ensuring microbial killing compared with Gzyme and Metrizyme
and was equivalent to the enzymatic detergents in cleaning ability.
Conclusions: In summary the KDS has excellent microbial-killing ability
in 3-minute exposures at room temperature and cleans as well as the
existing enzymatic detergent formulations that were tested. (Am J Infect
Control 2001;29:168-77)
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