Macquarie University
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Endoscope reprocessing and patient safety: evaluation of endoscopes and quality control

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posted on 2022-03-28, 09:57 authored by Lissandra Chaves de Sousa Santos
The difficulties in reprocessing gastrointestinal endoscopes and risk of patient to patient transmission of infectious organisms are recognized challenges in medicine. This thesis investigated gastrointestinal endoscope reprocessing both in the clinic and in the laboratory. Analysis of clinical data was performed for assessing soil level, contamination level and biofilm formation in four different settings: before and after manual cleaning, directly after endoscope reprocessing (12 to 48 hours after disinfection), following internal channels extraction for repair (clinically used endoscope from Australia and Brazil) and environmental sampling of endoscopy unit surfaces. Experimental analysis involved investigation of endoscope internal channels for surface damage and its relationship to frequency of use. The tests used for the analysis were adenosine triphosphate (ATP) bioluminescence for presence of soil, polymerase chain reaction (PCR) for bacterial load, microbial culture for viable bacterial numbers, scanning electron microscopy (SEM) for biofilm presence and stylus profilometer for surface roughness. Statistical analysis was performed by descriptive analysis, Mann-Whitney, Wilcoxon and Spearman tests, p<0.05, using IBM SPSS Statistics version 23.0. Before and after cleaning analysis of 99 endoscopes showed cleaning effectively reducing soil (p<0.001) and microbial contamination level (p=0.03). After complete reprocessing, all 75 endoscopes tested showed reduced soil contamination (all samples < 50RLU, from internal and external area); however the median microbial load was 3 Log10 and 10% of samples were culture positive. Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus hominis, Staphylococcus capitis, Roseomonas gilardii and Micrococcus luteus were isolated after endoscope reprocessing. Environmental samples were obtained from the nursing station and procedure room. Nine of the 24 (38%) samples had ATP values > 100 RLU and were then samples for microbial load by culturing. The areas with more contamination were the procedure room´s pipe and nursing station chair´s lift. Some potential pathogenic microorganisms were isolated (i.e. Shigella spp. and E.coli). Endoscope biopsy channel analysis showed that samples from Brazil had higher contamination levels than Australian samples (p<0.001). All channels analyzed were contaminated with soil and biofilm and presented damaged surfaces, however Brazilian samples were also contaminated with blood cells, neutrophils and fungus. Clinically used endoscope channels (median=526.82 A) were significantly rougher than new (median=357.8 A) endoscope channels (p=0.03). The increased roughness in used endoscope channels could provide a good environment for bacteria and patients' soil attachment, making cleaning and disinfection harder and contributing for biofilm formation. On in vitro model, tubing damage was consistent and higher than new after 500 passages of biopsy forceps and bacteria attach to internal surface of the tube with 30 minutes of flow contact. We conclude that even with low microbial load on endoscopes there is a potential risk of cross-infection associated with biofilm formation, frequency and quantity of use and time for reprocessing, which can easily compromise the accomplishment of endoscope reprocessing and therefore, patient safety.


Table of Contents

Chapter 1. Literature review -- Chapter 2. Temporal trends on endoscope reprocessing -- Chapter 3. Material and methods -- Chapter 4. Assessing manual cleaning of flexible endoscope by measuring soil and microbial contamination levels -- Chapter 5. Evaluation of endoscope reprocessing : high level disinfection -- Chapter 6. Assessing cleaning and bacterial load on endoscopy unit surfaces -- Chapter 7. Endoscope channel contamination evolution -- Chapter 8. A preliminary study on the contribution od endoscope channel damage to biofilm formation -- Chapter 9. General discussion and conclusion -- References.


Bibliography: pages 127-140 Empirical thesis.

Awarding Institution

Macquarie University

Degree Type

Thesis PhD


PhD, Macquarie University, Faculty of Medicine and Health Sciences, Department of Biomedical Sciences

Department, Centre or School

Department of Biomedical Sciences

Year of Award


Principal Supervisor

Karen Vickery

Additional Supervisor 1

Honghua Hu


Copyright Lissandra Chaves de Sousa Santos 2017. Copyright disclaimer:




1 online resource (xvi, 140 pages) illustrations (some colour)

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