Enzymatic detergent reuse in gastroscope processing: a potential source of microorganism transmission

Objective: to evaluate the potential contamination of enzymatic detergent from its reuse and to identify the microbiological profile in the solution used to clean gastrointestinal endoscopic devices. Method: cross-sectional study based on microbiological analysis of 76 aliquots of 19 different enzymatic detergent solutions used to clean endoscopic devices. The aliquots were homogenized, subjected to Millipore® 0.45 µm membrane filtration and the presumptive identification of microorganisms was performed by biochemical-physiological methods according to previously established specific bacterial groups that are of clinical and epidemiological relevance. Results: the mean values, as well as the standard deviation and the median, of the enzymatic detergent microbial load increased as the solution was reused. There was a significant difference between the means of after first use and after fifth reuse. A total of 97 microorganisms were identified, with predominance of the coagulase-negative Staphylococcus, Pseudomonas spp., Klebsiella spp., Enterobacter spp. genus, and Escherichia coli species. Conclusion: the reuse of the enzymatic detergent solution is a risk to the safe processing of endoscopic devices, evidenced by its contamination with pathogenic potential microorganisms, since the enzymatic detergent has no bactericidal property and can contribute as an important source for outbreaks in patients under such procedures.


Introduction
Gastrointestinal endoscopic devices are equipment that cause great concern about processing.
Used during the digestive endoscopy examination, these devices have external and internal surfaces exposed to high microbial load from their contact with the gastrointestinal tract, which makes proper decontamination necessary after each procedure to avoid cross contamination, to protect the team that reprocesses it against transmission of microorganisms and to prevent misdiagnosis, since biopsy fragments may remain inside the equipment and may be confused with those of another patient (1)(2)(3) .
Evidence suggests that the transmission of pathogens through endoscopic devices is an extremely rare event when the guidelines for processing these devices are respected (3)(4)(5) . The frequency of infection in digestive endoscopy is estimated to be 1 in 1.8 million procedures performed (1) . However, it is possible that this data underestimates the actual incidence of contamination since there are few estimates of infections resulting from these tests (3,6) .
However, when these infections occur, they can cause serious harm to the patient's health, as they include serious diseases such as sepsis, bacteremia, pneumonia, gastroenteritis, and hepatitis B and C (6)(7) .
In 2013, in the United States, inadequate processing of endoscopic devices was responsible for the largest outbreak of carbapenem-resistant Enterobacteriaceae ever recorded. Patients who underwent endoscopic retrograde cholangiopancreatography (ERCP) were affected and during the period more than 18 deaths were reported (8)(9)(10)(11) .
In order to achieve the utmost processing efficiency of endoscopic devices, it is important that both the process steps and the specific characteristics of the products used in cleaning these devices are complied.
In this context, nursing plays a central role as the processing of these devices is performed by them in most health services. It is the nursing professionals who, besides helping the endoscopic procedure, are responsible for the cleaning, disinfection, rinsing, storage of devices and preparation of sanitizing solutions (12) .
One of the products widely used in the processing of these equipment is the enzymatic detergent. Its function the breakdown of the organic matter of the devices after clinical use. Its reuse during cleaning of endoscopic devices is expressly warned by national and international institutions, associations and societies under penalty of efficiency loss (13)(14)(15)(16) . However, it is known that in clinical practice this solution has been reused several times for immersion of different equipment.
This practice aims to reduce costs in endoscope processing without considering the impact of this reuse on the processing quality of devices, since enzymatic detergent has no bactericidal property (3,17) . There are few studies addressing the efficiency of the solution during its use in clinical practice, especially directly, as pointed sometimes that the reuse of enzymatic detergent may contribute to the recontamination of devices, compromising the action proposed by the solution (18)(19) .

Results
In The descriptive analysis of the microbial load recovered in the enzymatic detergent solution during the different reuses is presented according to Table 1.   13.41x10 6 CFU in each solution after the fifth product reuse (5.60x10 5 CFU, considering the median).
The reuse of the solution configures a source of transmission of microorganisms, since it can increase the microbial load of the endoscopic device and favor processing failures of this equipment. This aspect draws considerable attention when thinking that an endoscopic device may, after contact with the patient's microbiota, present an average contamination of 10 9 to 10 12 CFU per equipment (20) .
In addition, the quantitative increase of microorganisms by the reuse of enzymatic detergent may make removal even more difficult during cleaning and thus favoring biofilm formation (21) . Studies show that cleaning and disinfection products commonly used in endoscopic device processing are not capable of removing biofilm in its entirety, which may allow the disintegration and transmission of microorganisms (22)(23)(24) . This is a matter of concern, since bacteria involved in biofilm formation may have up to 1,000 times greater resistance to antimicrobials compared to their suspension form (25) .
Regarding of this microorganism was related to failures in the duodenoscopic processing used in the procedure (28) .
The same happened between 2008 and 2009 in two hospitals in the United States, where Klebsiella pneumoniae was identified in seven patients who had also undergone ERCP. In these cases, all clones were resistant to Imipenem (29) .
Pseudomonas spp., a microorganism recovered in 63.3% of the aliquots referring to the fifth reuse of the enzymatic detergent solution, is an important cause of infections and outbreaks, especially in immunocompromised patients. It is the pathogen most commonly isolated in patients hospitalized for more than one week and is a frequent cause of healthcarerelated infections (30) . Pseudomonas aeruginosa has been the most reported microorganism responsible for the transmission of infection during gastrointestinal endoscopy (5) .
Endoscope contamination by P. aeruginosa is mainly associated with equipment processing failures, to the quality of the water supplied to the endoscopy sector, and improper drying of the endoscope channels, since such microorganism has a preference for humid environments (1,(31)(32) . Infections following post endoscopy procedures due to contamination by Pseudomonas spp.
In this study, before the first use of the enzymatic detergent solution, Staphylococcus spp. negative coagulase and non-fermenting Gram negative rods were recovered. Such findings are inferred from the potential contamination of the solution storage container, either through contamination of improper handling or cleaning.
These findings corroborate studies that identified Staphylococcus spp. negative coagulase as the most frequently isolated microorganism (44.5%) in the hands of the evaluated health professionals (33) . This concern remained a major focus of attention for the reports released in 2017 and 2018 (36) .
Clearly, the processing of endoscopic equipment is a major challenge for services because of its complex design, numerous narrow channels, and for being a task with of a sequence spanning over 100 interconnected and dependent steps. All steps must be strictly followed, as failures in any of them can endanger the safety of the entire process (5,19,37) . The use of enzymatic detergent is only part of the cleaning step, however, when used incorrectly can negatively impact the whole process.

Conclusion
The average microbial load recovered from enzymatic detergent solutions was increasing over reuse. Mean values greater than 10 6 CFU per solution were verified from the third use. There was a significant difference between the means after first use and after fifth reuse (p-value 0.011).

Contamination by Gram positive microorganisms
was always lower after the enzymatic detergent was reused, unlike Gram negative. Pseudomonas spp. the most frequently isolated microorganism.
Proper processing of endoscopic devices is a challenge for the nursing staff, given the difficulties inherent in the process due to the complex design of the equipment and the many steps to follow. This scenario can be considered even worse in underdeveloped and developing countries, where services are generally limited to essentially manual processing. In addition, the sectors generally have a nursing staff with fewer professionals than necessary, and work overload may contribute to insufficient adherence to established protocols.
There are numerous guidelines and steps that the endoscopic device must undergo in order to achieve effective processing. All recommendations must be periodically reviewed by the processing team, as each action taken can strongly impact the results to be achieved at the end of the process, especially when not done or poorly performed. Further research aimed at quantitative analysis of microbial load present in endoscopic apparatus before and after immersion in reused enzymatic detergent compared to unused detergent is suggested to consolidate the results presented in this study.