Endoscope cleaning
dismantled and evidence of biofilm was found in its undamaged channels, which could not be removed despite repeated rounds of high-level disinfection (HLD). This demonstrates ineffective cleaning as well as disinfection, as in an ideal process the biofilm would have been physically removed before HLD occurred. A second example involved 27 patients becoming colonised with multidrug-resistant Klebsiella pneumonia, with 10 developing an active infection.16
This outbreak was ultimately
traced to two endoscopes persistently contaminated with K. pneumonia over 8 months. Given this evidence, it is likely that it is the formation of protective biofilms that allows bacteria to persist within these endoscope channels over long periods of time. Bacteria in biofilms can also develop resistance
to HLD, making it critical that endoscope biofilms are removed during the manual cleaning stage.17
In one study, carbapenem-resistant
enterobacterales (CRE) showed increased tolerance to peracetic acid (PAA) when grown as a biofilm. K. pneumoniae isolated from an outbreak involving a duodenoscope showed weak resistance to PAA in its planktonic (free-living) form.18
When grown as a biofilm, the bacteria
showed resistance to PAA even at a concentration used for high-level disinfection.
Tested against the most robust biofilm models Biofilm found in endoscopes in clinical use is often fixed to the surface from repeated cycles of HLD and drying, meaning that mechanical action is critical for its removal.19 Traditional biofilm models used to assess efficacy are not representative, as they do not take into account multiple cycles of wetting and drying. There is a need to develop additional test methods that better represent the conditions
Figure 1 The stages of endoscope reprocessing; manual cleaning of channels is recognised as the most important.
Biofilm found in endoscopes in clinical use is often fixed to the surface from repeated cycles of HLD and drying, meaning that mechanical action is critical for its removal.
endoscopes undergo in clinical use, to ensure that any new cleaning approach has the most robust efficacy data. The cyclic-buildup biofilm model is the closest
available representation of biofilm isolated from endoscopes in clinical use.19
Traditional
biofilm models for testing are single-organism biofilms that are continuously hydrated, and do not involve multiple cycles of wetting and drying, the use of fixative chemicals, or the growth of biofilm in channels of different diameters.
Associated with less physical discomfort for staff Manual cleaning can be physically demanding, with reprocessing staff experiencing discomfort and pain from leaning over sinks, scrubbing endoscopes and standing for long hours.21 More healthcare professionals who performed manual cleaning with HLD reported occupational health issues at baseline compared with those using an automated endoscopic cleaning and reprocessing machine (65.4% vs 50%).22
Clinical Biofilm13 Includes potential GI pathogens
Grows in polytetrafluoroethylene (PTFE) channels Consists of multiple organisms Grows over >5 days
Subjected to multiple cycles of drying/wetting Exposed to high-level disinfectants
Crosslinking of amino acids induced by fixative chemicals Cycles of reinoculation
Grows in both small and large channels
✓ ✓ ✓ ✓ ✓ ✓
✓* ✓ ✓
(isolated from contaminated endoscopes) After six months, there was an increase in
symptoms among employees who manually cleaned with HLD, compared with a decrease in employees who used an endoscopic cleaning and reprocessing machine (90% vs 25%).22 In another study, three-quarters of
respondents reported experiencing fatigue or discomfort in association with cleaning duodenoscopes. Respondents identified the most discomfort involved the lower back, neck and shoulders.21
Physical discomfort
made manual cleaning difficult for 64% of respondents. The same proportion of respondents also
reported reductions in manual cleaning effectiveness.21
A new approach to cleaning
should reduce the physical burden on reprocessing staff, ideally through automation of processes.
Automation of key cleaning processes Partial or complete automation could reduce
Cyclic-buildup Biofilm19
✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓ ✓
1.4 mm and 3.7 mm diameter PTFE tubing
Table 2. Characteristics of clinical biofilm compared to traditional and cyclic-buildup biofilm. May 2024 I
www.clinicalservicesjournal.com 55 Traditional Biofilm20
✓ ✓ - - - - - - -
6mm diameter tubing only
*Where glutaraldehyde (GTA) and ortho-phthalaldehyde (OPA) are used
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