Cleaning of in-hospital flexible endoscopes: Limitations and challenges

Abstract Objective: to analyze the cleaning process of gastroscopes, colonoscopes and duodenoscopes in eight in-hospital health services. Method: a cross-sectional study conducted with 22 endoscopes (eight gastroscopes, eight colonoscopes and six duodenoscopes), and microbiological analysis of 60 samples of air/water channels (all endoscopes) and elevator (duodenoscopes), in addition to protein testing. Descriptive statistics with calculation of frequencies and central tendency measures was used in data analysis. Results: the processing of 22 endoscopes was monitored with microbiological analysis for 60 channels. In the pre-cleaning procedure, in 82.3% (14/17) of the devices, gauze was used in cleaning the insertion tube. Incomplete immersion of the endoscope in detergent solution occurred in 72.3% (17/22) of the cases, and in 63.6% (14/22) there was no standardization of filling-in of the channels. Friction of the biopsy channel was not performed in 13.6% (3/22) of the devices. In the microbiological analysis, 25% (7/32) of the samples from the stored endoscopes were positive for microbial growth (from 2x101 to 9.5x104 CFU/mL), while after processing, contamination was 32% (9/28). Protein residues in the elevator channel were detected in 33% of duodenoscopes. Conclusion: the results indicate important gaps in the stages of pre-cleaning and cleaning of endoscopes that, associated with presence of protein residues and growth of microorganisms of epidemiological importance, indicate limitations in safety of the processing procedures, which can compromise the disinfection processes and, consequently, their safe use among patients subjected to such tests.

Madureira RAS, Oliveira AC. Data collection took place in a maximum of two visits, requiring the researcher to remain on site until completion of the exam schedule of that day. It is important to note that the process was monitored from pre-cleaning at the point of use to storage of the equipment. However, only the pre-cleaning and cleaning stages were addressed in this article.
The technician invited to participate in the study was the one scheduled at the service for processing on the day of the visit. It is worth clarifying that this participation of the technician was voluntarily, after the invitation, guaranteeing him full autonomy in choosing to participate or not in the research, or even withdrawing his participation, without any kind of coercion, restraints or penalties.
In order to evaluate effectiveness of the processing, samples were collected from the air/water channels (all endoscopes) and from the elevator (duodenoscopes) at two moments: stored equipment, before first use of the day; and after processing, at the end of the shift. These samples were subjected to microbiological analysis. In addition to that, protein testing was applied to the elevator channel after the cleaning stage. It is noted that the collection procedures were performed in the same devices at two moments, therefore sampling a total of 22 devices. Sample collection from the air/water channels was carried out by the researcher, with the support of a Nursing undergraduate student duly trained for this activity. Aseptic technique was used, by means of the flush method, in which, with the aid of a syringe, 40 ml of double-distilled water were injected into the channel and the fluid obtained in the distal portion of the insertion tube was collected in a sterile container and sent for analysis (10) . For the elevator channel, the surface friction technique was used with the aid of a swab, described in other studies (11)(12) . In this method, the elevator channel sample was obtained from all faces of the device (anterior and posterior), by friction with the aid of a swab and double-distilled water injection.
After collection, the tubes with the samples were placed under refrigeration in a thermal box suitable for transportation and with temperature control, remaining between 2°C and 8°C, until they were sent to the laboratory, which was in charge of the researcher himself, in order to provide safety in sending the samples.
As for the method to perform the examination, it is noted that the culture was performed in an enrichment medium. Ten ml of the sample were used for enrichment and then one ml for each plate. The culture and isolation medium allowed for the growth of bacteria and fungi, Kirby-Bauer manual method (diffusion disk method) was adopted for the sensitivity tests, following the BrCast criteria. In the case of mycobacteria, identification varied  Rev. Latino-Am. Enfermagem 2022;30:e3684.

Ethical aspects
The current study was submitted to and approved by the Departmental Chamber of the Advisor and by the UFMG Ethics Committee under No. 4,574,663. Participation of the institutions, after consent, took place voluntarily and anonymously, without any financial benefit or coercion to participate.
Participation of the professionals was formalized by signing the Free and Informed Consent Form.

Results
Eight in-hospital Endoscopy services took part in the study, 75% of which were administered by the institution itself and 62.5% were private, i.e., they were services that provided care to individual patients with or without health insurance. Regarding the method used to process the endoscopes, the manual method was adopted in 50% of the devices and the mixed method (manual/automated), in the other 50%.
The processing and microbiological analysis of 22 endoscopic devices (eight gastroscopes, eight colonoscopes and six duodenoscopes) were monitored, obtaining 60 samples from the air/water channels of all endoscopes and elevator (duodenoscopes). Although all endoscopic processing stages were observed, Table 1 presents and emphasizes those of pre-cleaning and cleaning because they were the main focus of this study. After the microbiological analysis, it was identified that, of the 28 samples obtained after processing and of the 32 from the stored equipment, 32% and 25%, respectively, were positive for growth of microorganisms ( Figure 1).
In relation to the protein test, it was found that 33.3% (2/6) of the sampled duodenoscopes presented protein residues after cleaning, identified as devices whose elevator channel was not subjected to friction.

Discussion
Although pre-cleaning of the endoscope channels at  The frequency of the microorganisms isolated in the devices, regardless of the sensitivity profile, is presented in Figure 2 below. Madureira RAS, Oliveira AC.
especially inside the channels, in order to contribute to the cleaning process and avoid biofilm formation, disaggregating organic matter and other residues (1,(13)(14)(15)(16) .
Therefore, detergent use as well as filling of the channels in adequate volume (injection of 200-250 ml) and their aspiration for a period of 10-20 seconds are fundamental in this stage (13) .
The importance of carrying out pre-cleaning of the endoscopes is widely highlighted among the recommendations by international societies (1,3,(17)(18) , and its inadequate execution, such as use of non-recommended inputs and solutions and non-standardization to fill the equipment channels, pointed out in this study, or its omission as recorded in another research study (19) , because, for the detergent to facilitate the reduction of dirt and microorganisms, it is considered essential that the endoscope and its accessories remain fully immersed for the time recommended by the manufacturer (1,3,15) .
Another important gap identified was friction of the channels with single diameter brushes in 63.6% (14/22) of the endoscopes observed. Adoption of this practice generates concerns regarding effectiveness of the cleaning procedure. The guidelines recommend using different brushes, with sizes and diameters compatible with each channel, so that the bristles have contact with the surface of the structures, in order to allow for the reduction of organic residues and microorganisms present in the equipment (14)(15)17) . In order to avoid cross-contamination across the devices, the brushes should preferably be single-use (13) . If it is not possible, when reusable, it is indispensable that, after each use, they are subjected to high-level cleaning and disinfection or sterilization (13,20) .
When it comes to duodenoscopes, especially the models consisting of an elevator channel with fixed protection, the challenge for cleaning is even greater because the device does not allow reaching all its faces by brushing, with the part located after the elevator mechanism being the most difficult to access (21) .
Also contrary to the scientific recommendations, among the six duodenoscopes evaluated, in only one device the elevator channel was properly rubbed, that is, promoting articulation of the elevator mechanism and with a brush compatible with the channel. In the institutions where the automated method was adopted, most of the professionals were unaware that the elevator mechanism should remain upright throughout the process, in order to allow greater contact with the cleaning and disinfection solutions (3,14) . The inadequate position of this device deserves to be highlighted due to its potential accumulation of dirt and microorganisms, especially on its posterior face, which may favor maintenance of microorganisms in the structure (22) .
Such findings give rise to a special look at this stage of the process, as the professionals' non-perception of the elevator mechanism as a threat to safe use of the duodenoscopes is a matter of concern (23) , as failures during its processing have been attributed as important causes of several infectious outbreaks, with involvement of numerous patients in different countries in the world (16,(24)(25) . This lack of knowledge reinforces the need to train Endoscopy teams more frequently on correct cleaning and disinfection of these devices (22)(23) .
Given the major challenge for the effectiveness of endoscope cleaning, a number of societies have emphasized the importance of implementing methods that enable evaluation of this process (3,13) . The current study identified that 62.5% (5/8) of the services adopted tests for validation of the cleaning procedure in their routine.
In these institutions, the ATP bioluminescence test was used as a potential marker of cleaning adequacy, with up to 200 Relative Light Units (RLUs) being considered as an acceptable value (26) . However, it is important to mention that the result of this test should be read with caution, as there is variability in the scale of the reference values according to each manufacturer. Thus, it is fundamental that the brand of the product used and its respective guidelines are observed, in order to avoid misinterpretations in the results (27) .
It is also worth noting that ATP has been indicated as an important tool to monitor the cleaning technique performed by the professionals (8, [28][29] . However, ATP detection after cleaning a health product represents uptake of live cell energy. Thus, its use needs to be careful since, although ATP provides values that meet the references, there is the possibility of the presence of non-viable cells in the channels, which may compromise effectiveness of the processing procedure and which will