In recent years, flexible endoscope reprocessing failure has been listed in the “Top 10 Health Technology Hazards” issued annually by the Emergency Care Research Institute (ECRI) for five consecutive years and even ranked the top one of the list in the year 2016. With the continuous advancement of gastrointestinal endoscopy technology, new endoscopic technique may bring new medical risks and medical technique hazards while improving medical quality and patient safety. According to the report, from 1996 to 2015, among 1389 cases of patients under duodenoscopy procedures in Europe, 32 cases were found of being infected with multidrug resistant
The microbiological monitoring can evaluate the effect and quality of endoscopic reprocessing, and is beneficial to identify sources of contamination, correct cleaning, and disinfection methods, and thus preventing the spread of nosocomial infections It is mentioned in the guidelines from Europe, Australia, and New Zealand [
A total of 12 gastrointestinal endoscopes were randomly selected from October 2018 to February 2019 from the gastrointestinal endoscopy center of a tertiary hospital in Shanghai, included 10 gastroscopes (Olympus, Japan), 2 colonoscopes (Olympus, Japan), and 24 disc brushes (Normandie Endo Technologies, France, general type). The neutralizer is an aldehyde neutralization enrichment medium (Haibo Biotechnology, China).
According to the operation requirements of “Regulation for cleaning and disinfection technique of flexible endoscope WS 507-2016”, every endoscope should be strictly reprocessed in accordance with the procedures of “precleaning, leak testing, washing, rinsing, disinfection, terminal rinsing, and drying”.
In order to avoid the deviation of the detection results due to the difference in the amount of bacteria contaminated between different endoscopes, two approaches were used in this experiment. One was to perform the biopsy channel sampling, the entire channel sampling, and disc brush sampling continuously on the same gastrointestinal endoscope in the same day for further testing, which was called as continuous sampling; the other was to perform biopsy channel sampling, entire channel sampling, and disc brush sampling on the same endoscope for three days respectively for further testing, which was called as intermittent sampling. The entire operating procedure followed the principle of aseptic technique. A peristaltic pump was used and an injection needle was repeatedly injected for 2-3 times for full amount collection. Biopsy channel sampling group (Group A): the endoscopes after reprocessed were sampled as below: 50 ml of the neutralizer was extracted with a sterile syringe, injected, and flushed the instrument channel through the biopsy port of the control section, and the total volume of elution was collected from the distal end of the endoscope. The eluate was thoroughly mixed and sent to the laboratory of Shanghai Municipal Center for Disease Control and Prevention within 2 hours for culturing and colony counting (CFU/piece) (Figure Entire channel sampling group (Group B): the endoscopes after reprocessed were sampled as below: 50 ml of the neutralizer was extracted with a sterile syringe. A sterile film was placed onto the air/water port, suction, and instrument port of the endoscopic control section. Installed the sterile endoscope specialized washing joint to seal the air/water injection port, suction port; and instrument port of the endoscope control section. The neutralizer was injected and flushed through the endoscope channel from the suction port beside the endoscope light guiding connector, through the suction and biopsy channel and then the total volume of elution was collected from the distal end of the endoscope. The eluate was thoroughly mixed and sent to the laboratory of Shanghai Municipal Center for Disease Control and Prevention within 2 hours for culturing and colony counting (CFU/piece) (Figure Disc brush sampling group (Group C): the endoscopes after reprocessed were sampled as the procedure below: a blunt head of a sterile disposable disc brush was inserted into the instrument port, and the instrument channel was brushed until the brush end completely exited the instrument channel outlet of the distal end. The upper part of the brush was cut off (2 cm) using sterile scissors, then the clipped brush was put into a sterile bottle for testing. 50 ml of neutralizer was extracted with a sterile syringe and injected into the instrument port, then the total volume of elution was collected from the distal end of the endoscope into the same bottle used for the testing of the clipped brush. The eluate was thoroughly mixed with the brush inside the sterile bottle and sent to the laboratory of Shanghai Municipal Center for Disease Control and Prevention within 2 hours for culturing and colony counting (CFU/piece) (Figure
Flush the instrument channel from the control section (Group A).
Flush the instrument and suction channel from the suction port (Group B). (a) Close the instrument port, (b) close the air/water and suction port, and (c) flush the suction port.
Brush-flush the instrument channel from the instrument port (Group C). (a) Brush the instrument channel, (b) cut off the brush, and (c) cut into the bottle.
In reference to the “Hygienic standard for disinfection in hospitals GB 15982-2012”. The test solution was mixed thoroughly with a vortex mixer, inoculated with 1 ml of the mixed eluate in to two plates respectively, 20 ml of the molten nutrient agar medium cooled to 40°C–45°C was poured into each plate, and cultured in an incubator at 35°C for 48 hours, then the number of colonies (CFU/piece) were counted. The remaining eluate (48 ml) was filtered under sterile conditions using a filter membrane (0.45
The cultured results of the samples were recorded. When the filter membrane method is in countable, the total number of colonies (CFU/piece) =
The data was analyzed using SPSS 20.0. The statistical methods used are chi-square test for counting data and independent sample Kruskal-Walis test for measurement data.
In this study, a total of 12 flexible endoscopes were collected using continuous sampling approach, with colony counts ranging from 0 to 21 CFU/piece. The detection rate of bacteria in the disc brush group (33.3%), and the entire channel group (33.3%) was higher than that of the biopsy channel group (8.3%). Among the 12 endoscopes sampled with intermittent approach, with colony counts ranging from 0 to 36 CFU/piece, the detection rate of bacteria from high to low was the disc brush group (50%), the entire channel group (41.7%), and the biopsy channel group (8.3%). It showed that the detection rate of bacteria for either the disc brush group or the entire channel group was higher than the biopsy channel group (Tables
Comparison of bacterial colony counts by different sampling methods (continuous sampling).
Sampling method | Max | Min |
|
|
|||||
---|---|---|---|---|---|---|---|---|---|
Biopsy channel (Group A) | 1 | 0 | |||||||
Entire channel (Group B) | 1 | 0 | |||||||
Disc brush (Group C) | 21 | 0 | |||||||
2.657 | 0.265 |
Comparison of bacterial colony counts by different sampling methods (intermittent sampling).
Sampling method | Max | Min |
|
|
|||||
---|---|---|---|---|---|---|---|---|---|
Biopsy channel (Group A) | 1 | 0 | |||||||
Entire channel (Group B) | 36 | 0 | |||||||
Disc brush (Group C) | 30 | 0 | |||||||
5.626 | 0.060 |
Comparison of bacterial colony counts group by different sampling methods (continuous sampling).
Sampling method | Colony count group | |
---|---|---|
<1 ( |
≥1 ( | |
Biopsy channel (Group A) | 11 (91.7) | 1 (8.3) |
Entire channel (Group B) | 8 (66.7) | 4 (33.3) |
Disc brush (Group C) | 8 (66.7) | 4 (33.3) |
Total | 27 (75) | 9 (25) |
Comparison of colony counts group by different sampling methods (intermittent sampling).
Sampling method | Colony counts group | |
---|---|---|
<1 ( |
≥1 ( | |
Biopsy channel (Group A) | 11 (91.7) | 1 (8.3) |
Entire channel (Group B) | 7 (58.3) | 5 (41.7) |
Disc brush (Group C) | 6 (50) | 6 (50) |
Total | 24 (66.7) | 12 (33.3) |
Gastrointestinal endoscopy is an important minimal invasive diagnosis and treatment method for gastrointestinal tract, pancreaticobiliary, and other diseases. It has complex and delicate structure and is difficult to thoroughly reprocess. In recent years, there have been many reports of endoscopy related healthcare associated infections with complex influencing factors. As a reusable medical device that directly contacts with the mucosa of a patient’s organs, high-level disinfection, or sterilization must be achieved before use. However, studies have shown that even if the endoscope and accessories are treated strictly in accordance with guideline recommended for cleaning and disinfection methods, endoscopic associated infections are still possible to happen [
A prospective study of the disinfection effect of a duodenoscope after disinfection and drying in one hospital found that the positive rate was 5–15.5% [
In the endoscopic microbiology sampling method of our study, the entire channel group sampling was to inject the neutralizer from the instrument port beside the endoscope light guiding connector, and seal the suction port, the air/water injection port and the instrument port of the endoscope control section with the washing joint, and then collect the elution from the distal end of the endoscope. The path taken by the instrument channel sampling group is the same as the brush sampling group. The single biopsy channel was lacking the sampling of the suction channel compared with the entire channel group. However, the disc brush sampling method can brush and wash the inner surface of the endoscope lumen when compared with the simple flushing method of washing off the attachment from the inner surface of lumen. It has been shown that brush sampling method could scrub the endoscope channel and remove separately the new and old contaminants from endoscope channel [
The results of this study shows that the positive rates of the entire channel sampling method and the disc brush sampling method are much higher than the conventional sampling method; whether, by continuous or intermittent approach. The conventional sampling method has been applied in China for nearly 15 years since 2004, and it will continue to be performed by healthcare practitioners in the future. There have been many international guidelines regarding to the endoscopic microbiology sampling, but the lack of well-defined illustrated operational procedures for specific sampling methods is likely to result in denormalization of microbiological sampling and reduced evaluability of results. Therefore, in the future, we can improve the sampling method for endoscopic microbiology culture through continuous research. At the same time, since the positive and negative judgments of the cultured results have no aligned international standard [
It was found in this study that both the entire channel sampling and the disc brush sampling method have higher bacterial positive detection rate than the conventional biopsy channel sampling method, which further indicates that the endoscopic sampling method being implemented currently needs further improvement. At the same time, this study also has certain limitations. This study is a single-center study. Meanwhile, the samples we used came from the gastrointestinal endoscopes used in daily clinical practice. The original bioburdens of the endoscope were not under control. Larger sample size and multi-center sites as well as endoscopic simulation models combined with laboratory experiments are needed in the future. Validation and comparison under standard condition could better increase the reliability and scientificity of the study.
The data used to support the findings of this study are included within the article.
The first author is Su Ma, the co-first author is Lili Feng, the co-first author is Wenxia Ding.
The authors declare that they have no conflicts of interest.
This research was supported by Research fund for infection prevention and control of Chinese Geriatrics Society (GRYJ-YK2018045) and Research fund for nursing of Changhai hospital (2018HLZD08).