Flexible gastrointestinal endoscopic reprocessing

Abstract

Two articles in this month's journal focus on specific areas of controversy in the reprocessing of flexible gastrointestinal endoscopes between patient use. In the study by Urayama et al.,1Urayama S Kozarek RA Sumida S Raltz S Merriam L Pethigal P. Mycobacteria and glutaraldehyde: is high-level disinfection of endoscopes possible? A pilot study.Gastrointest Endosc. 1996; 43: 451-456Abstract Full Text Full Text PDF PubMed Google Scholar the authors demonstrated that manual cleaning of endoscopes heavily contaminated with laboratory-cultured mycobacteria (102 colony forming units per instrument) resulted in greater than a 104 log reduction in numbers of viable cells recovered when the biopsy channels of five instruments were sampled. However, using two laboratory assay methods, they also showed that extending the endoscope exposure time in 2% alkaline glutaraldehyde from 10 to 20 minutes (presumably at room temperature) did not completely eradicate the mycobacterial inocula in the channels. Further, extending the exposure time to 45 minutes showed recoverable mycobacteria in four of five instruments. The highest numbers of recoverable mycobacteria were recovered in the rinse samples from the duodenoscope elevator channels. Seventy percent isopropyl alcohol, used as a “secondary” tuberculocidal disinfectant in sequence after glutaraldehyde exposure and water rinsing, while helpful, was not universally effective in eliminating the mycobacterial inocula in all endoscopes tested. A major conclusion in the report was that intensive manual cleaning of these instruments appeared to be as important, if not more important, than the time of exposure to glutaraldehyde in lowering microbial numbers. The study by Merighi and coworkers2Merighi A Contato E Scogliarini R et al.Quality improvement in gastrointestinal endoscopy: microbiological surveillance of disinfection.Gastrointest Endosc. 1996; 43: 457-463Abstract Full Text Full Text PDF PubMed Google Scholar described implementation of a 2-year endoscope reprocessing quality assurance program augmented by a microbiologic surveillance regimen to assess and improve the disinfection of flexible gastrointestinal endoscopes as well as automated reprocessing machines in a routine clinical setting. Using relatively insensitive direct surface contact and channel rinsing methods for sampling and laboratory culture, qualitative results showed significant instances of postprocessing bacterial contamination on endoscope surfaces and in channels. The most frequently isolated organisms were a variety of Pseudomonas spp, and the predominant species was P. aeruginosa. Quantitative assays of rinse water in the automated reprocessing machine reservoir indicated that the reservoir was colonized with high levels of waterborne bacteria (104/ml) with P. aeruginosa being present in the majority of specimens taken over the 2-year period. This situation presumably resulted in postdisinfection contamination of the instruments, and the authors of the paper suggested a postprocessing rinse with ethyl alcohol as a “secondary” disinfecting procedure to reduce the levels of contamination due to the use of contaminated rinse water. The study results, however, showed this procedure to be only partially effective. The workers concluded that endoscope reprocessing machines should be redesigned to address elimination of microbial contamination (colonization?) and that more attention be paid to effective quality assurance programs in the endoscopy suite. Although not supported by the data presented, Merighi et al. also recommended a number of regimens that could easily be interpreted as double standards of patient care: (1) significantly increased time of exposure to glutaraldehyde at the end of an endoscopic session and before use on a patient known to be immunocompromised, (2) special disinfection of the automated disinfecting equipment before instruments are processed prior to certain procedures considered to be overtly invasive, and (3) alcohol rinsing immediately before certain invasive procedures. The data presented in these two papers are not surprising or unanticipated, and the authors of both concluded that more investigation is needed to address the ongoing dilemma of microbial contamination of endoscopes. What was emphatically reconfirmed was the problematic nature of assessing microbial contamination of physically complex medical instruments, both in the laboratory and in clinical settings.3Bond WW Hedrick E. Microbiological culturing of environmental and medical device surfaces.in: Clinical microbiology procedures handbook, section 11: epidemiologic and infection control microbiology. American Society for Microbiology, Washington, DC1992: 10-11Google Scholar What is curious is that neither article addressed the role of endoscope manufacturers in resolving these problems, even in light of the widely known fact that there are no validated, data-based methods for access, for cleaning, or for disinfecting or sterilizing these instruments presented in any of the manufacturers' current instruction manuals. An American Society of Testing Materials subcommittee has been working with flexible gastrointestinal endoscopic manufacturers over the past 4 years in an effort to devise a standardized test of adequacy of scope disinfection or sterilization. A recent report in the medical literature suggested that viruses and bacteria may be protected from germicidal agents by lubricants.4Lewis D Arens M. Resistance of microorganisms to disinfection in dental and medical devices.Nature Medicine. 1995; 1: 956-958Crossref PubMed Scopus (39) Google Scholar These data were also not surprising and, due to the study design, have been criticized as not being reflective of clinical situations, including the use of flexible fiberoptic endoscopes.5Alvarado CJ. Commentary: resistance of microorganisms to disinfection in dental and medical devices.APIC Newsletter. 1995, November/December; : 10-11Google Scholar, 6Muscarella LF. Sterilizing dental equipment.Nature Medicine. 1995; 1: 1223-1225Crossref PubMed Scopus (11) Google Scholar Further, recent label claims of proprietary glutaraldehyde-based germicides have been changed to reflect increased exposure time (and in some instances, increased temperature) necessary to effect high-level disinfection. Liquid chemical germicides (“disinfectant/sterilant” products) used to reprocess critical or semicritical medical instruments are regulated by the Food and Drug Administration (FDA), and cleared label claims for each commercial product are based on laboratory data supplied by the product manufacturer. Similar to the published study addressing the effects of lubricant masses “shielding” microorganisms from contact with a liquid chemical disinfectant, the laboratory protocol for FDA regulatory clearance does not consider the significant effect of thorough manual precleaning of instruments prior to high-level disinfection with a liquid chemical agent. The use of high-titer inocula in these tests and the inherent resistance of most mycobacteria to glutaraldehyde (due to the hard-to-penetrate waxy/lipid cell coat) are two significant reasons accounting for the prolonged exposure times (and sometimes elevated temperature) necessary for total inactivation of the test population. Recognizing that these in vitro laboratory tests reflect little of what occurs in a well run clinical endoscopy setting, these current label claim requirements have been criticized in the medical literature.7Rutala WA Weber DJ. FDA labeling requirements for disinfection of endoscopes: a counterpoint.Infect Control Hosp Epidemiol. 1995; 16: 231-235Crossref PubMed Google Scholar The “worst case scenario” (lack of adequate manual precleaning of flexible endoscopes and accessories) was considered extensively by the ASGE Ad Hoc Committee on Disinfection that recently reported their findings in a position statement addressing the reprocessing of flexible gastrointestinal endoscopes, which also appears in this month's journal.8American Society for Gastrointestinal Endoscopy Position Statement: Reprocessing of flexible gastrointestinal endoscopes. December, Manchester, Massachusetts1995Google Scholar The importance of meticulous manual precleaning prior to disinfection by either manual or automated techniques was stressed by the subcommittee. A quality assurance protocol emphasizing that only well-trained, certified specialists perform the manual cleaning of the instruments and accessories was considered integral to the success of the complete flexible gastrointestinal endoscope reprocessing regimen. Clear y, a significant decrease in bioburden can be achieved by thorough mechanical processing in and of itself.1Urayama S Kozarek RA Sumida S Raltz S Merriam L Pethigal P. Mycobacteria and glutaraldehyde: is high-level disinfection of endoscopes possible? A pilot study.Gastrointest Endosc. 1996; 43: 451-456Abstract Full Text Full Text PDF PubMed Google Scholar, 7Rutala WA Weber DJ. FDA labeling requirements for disinfection of endoscopes: a counterpoint.Infect Control Hosp Epidemiol. 1995; 16: 231-235Crossref PubMed Google Scholar Since essentially all reported instances of adverse patient events have been attributed to lapses in the manual cleaning process, it is essential that an effective precleaning protocol be consistently implemented.8American Society for Gastrointestinal Endoscopy Position Statement: Reprocessing of flexible gastrointestinal endoscopes. December, Manchester, Massachusetts1995Google Scholar The extended exposure times as indicated on the current labels of glutaraldehyde-based germicides would, of necessity, require additional expensive endoscopic instrumentation at virtually all gastrointestinal endoscopic centers. Concomitantly, there would be an increased risk of physical damage to the instrumentation due to the increased exposure to chemical corrosion and liquid submersion. There is also concern regarding increased potential of glutaraldehyde absorption by flexible endoscopes and subsequent leaching into the patient associated with repeated and prolonged immersion times. All these concerns are relevant, particularly in an era of cost containment and decreasing reimbursements for these procedures. With little evidence of adverse clinical effect in the medical literature, the gastrointestinal community, in general, is demanding evidence that increased exposure times to liquid chemical germicides are needed to increase theoretic levels of patient safety. The articles in this month's Gastrointestinal Endoscopy have simply reinforced the point that even with prolonged exposure to germicides, it is virtually impossible to consistently achieve a state of high-level disinfection (the absence of all recoverable microorganisms except for a low number of spore-forming bacteria). The major reason for this is the notorious physical complexity, fragility, and expense of the endoscopic instruments.9Bond WW Ott BJ Franke KA McCracken JE. Effective use of liquid chemical germicides on medical devices: instrument design problems.in: 4th ed. Disinfection, sterilization, and preservation. Lea and Febiger, Philadelphia1991: 1097-1106Google Scholar The Ad Hoc Committee on Disinfection recognized this fact and strongly recommended that endoscope manufacturers redesign their instruments to allow for easy disassembly, efficient and verifiable cleaning and, eventually, heat sterilization. Also, this recommendation has recently been voiced in a policy statement issued by the American Public Health Association.10American Public Health Association. Policy Statement No. 9417: establishment of clearly defined performance standards for between-patient processing of reusable endoscopic instruments and accessories.Am J Public Health. 1995; 85: 449-450Google Scholar Another strategy for improving infectious disease safety in endoscopy would be to utilize a disposable physical barrier between the patient and the endoscope. The recent development of sheathed gastrointestinal endoscopes is of contemporary interest in this regard and has justifiably received the attention of the infection control and endoscopy communities. Currently available as well are newly developed oxidizing liquid chemical germicides, e.g., peracetic acid, hydrogen peroxide, and peracetic acid/hydrogen peroxide combinations. These chemical germicides have been suggested as effective alternatives to glutaraldehyde for endoscope reprocessing. Obviously, much research in the form of carefully designed, conducted, and controlled laboratory and clinical studies is needed in this emerging area of concern. From the standpoint of the physician and infection control communities, the health and safety for all patients is the first and foremost concern. Without doubt, gastrointestinal patients have gained an enormous amount of benefit from the constantly increasing diagnostic and therapeutic potentials of gastrointestinal endoscopes. The currently recognized level of patient safety is high. However, it is essential that the manufacturers of gastrointestinal endoscopes quickly embark on development and improvement of instrument design with effective infection control and reprocessing that is simple, fast, and cost-efficient. The potential for infection transmission can be decreased significantly if the very next generation of endoscopic instrumentation is designed specifically for data-based, verifiable access, cleaning, and disinfection or sterilization. Emerging technologies are available to optimize the patient's margin of benefit and safety, and this should be the first, foremost, and common goal of the medical professions and of industry.