Liquid Chemical Sterilization Research Articles

Double high-level disinfection versus liquid chemical sterilization for reprocessing of duodenoscopes used for ERCP: a prospective randomized study

The potential for transmission of pathogenic organisms is a problem inherent to the current reusable duodenoscope design. Recent outbreaks of multidrug-resistant pathogenic organisms transmitted via duodenoscopes has brought to light the urgency of this problem. Microbiologic culturing of duodenoscopes and reprocessing with repeat high-level disinfection (HLD) or liquid chemical sterilization (LCS) have been offered as supplemental measures to enhance duodenoscope reprocessing by the U.S. Food and Drug Administration. This study aims to compare the efficacy of reprocessing duodenoscopes with double HLD (DHLD) versus LCS. We prospectively evaluated 2 different modalities of duodenoscope reprocessing from October 23, 2017 to September 24, 2018. Eligible duodenoscopes were randomly segregated to be reprocessed by either DHLD or LCS. Duodenoscopes were randomly cultured after reprocessing for surveillance based on an internal protocol. During the study period, there were 878 post-reprocessing surveillance cultures (453 in the DHLD group and 425 in the LCS group). Of all cultures, 17 were positive for any organism (1.9%). There was no significant difference of positive cultures when comparing the duodenoscopes undergoing DHLD (8 positive cultures, 1.8%) with duodenoscopes undergoing LCS (9 positive cultures, 2.1%; P= .8). Both groups had 2 cultures that grew high-concern organisms (.5% vs .5%, P=1.0). No multidrug-resistant organisms, including carbapenem-resistant enterobacteriaceae, were detected. DHLD and LCS both resulted in a low rate of positive cultures, for all organisms and for high-concern organisms. However, neither process completely eliminated positive cultures from duodenoscopes reprocessed with 2 different supplemental reprocessing strategies.

1 Double High-Level Disinfection vs. Sterilization for Reprocessing of Duodenoscopes Used for ERCP: A Prospective Study

INTRODUCTION: The potential for transmission of pathogenic organisms is a problem inherent to the current duodenoscope design. Recent outbreaks of multi-drug resistant pathogenic organisms transmitted via duodenoscopes has brought to light the urgency of this problem. Microbiological culturing of duodenoscopes and reprocessing with repeat high-level disinfection or liquid chemical sterilization have been offered as supplemental measures to enhance duodenoscope reprocessing by the US Food and Drug Administration (FDA). This study aims to compare the efficacy of reprocessing duodenoscopes with double high-level disinfection (DHLD) versus liquid chemical sterilization. METHODS: We prospectively evaluated two different modalities of duodenoscope reprocessing from 10/23/17 to 9/24/18. All operable duodenoscopes were segregated to be reprocessed by either DHLD (i.e., complete manual cleaning followed by automated reprocessing, repeated for two total cycles) or manual cleaning followed by liquid chemical sterilization. Duodenoscopes were randomly cultured post-reprocessing for surveillance based on an internal protocol. RESULTS: During the study time period, there were 878 post-reprocessing surveillance cultures (453 in the DHLD group and 425 in the sterilization group). Of all of the cultures, 17 were positive (1.9%). There was no significant difference of positive cultures when comparing the duodenoscopes undergoing DHLD (8 positive cultures, 1.8%) to duodenoscopes undergoing sterilization (9 positive cultures, 2.1%, P > 0.05). Both groups had two cultures that grew high-concern organisms. No multi-drug resistant organisms (MDRO), including carbapenem-resistant enterobacteriaceae (CRE), were detected. Organisms from positive cultures are presented in Table 1. CONCLUSION: DHLD and liquid chemical sterilization both resulted in a low rate of positive cultures, both for all organisms and for high-concern organisms, but neither process eliminated positive cultures from reprocessed duodenoscopes. A liquid chemical sterilization protocol did not improve the growth of organisms on surveillance cultures compared to DHLD.

Evaluation of 12-Week Shelf Life of Patient-Ready Endoscopes.

Current research suggests that for certain types of gastrointestinal endoscopes, longer shelf life (the interval of storage after which endoscopes should be reprocessed before their reuse) may not increase the likelihood of endoscope contamination. Scope contamination may, in fact, be related primarily to either inadequate disinfection processes or inadvertent contamination during storage, not to duration of storage. The purpose of this study evaluated the presence of bacteria and fungus following liquid chemical sterilization in colonoscopes and gastroscopes, after 12 weeks of shelf life during which time personal protective equipment was used during endoscope storage cabinet access. We stored four colonoscopes and two gastroscopes in a cabinet for 12 weeks after liquid chemical sterilization and the cabinet was only accessed during the 12-week period wearing personal protective equipment (gown and gloves). Scopes were tested for bacteria and fungus at the end of 12 weeks. No bacteria or fungus grew on any of the scopes. This study provides further support that contaminated endoscopes may be related to either inadequate disinfection or contamination during storage, not shelf life.

Duodenoscope reprocessing practice patterns in U.S. endoscopy centers: a survey study

After recent outbreaks of duodenoscope-related infections from multidrug-resistant organisms (MDRO), the United States Food and Drug Administration (FDA) recommended implementing 1 or more of 4 enhanced reprocessing measures in addition to updated manual cleaning methods and high-level disinfection (HLD). The implementation of these techniques in endoscopy facilities and provider opinions regarding reprocessing priorities remain unknown. Physicians, nurse managers, nurses, and infection control staff at endoscopy units performing ERCP in the United States were surveyed to assess current institutional practices and individual opinions regarding future reprocessing solutions. A total of 249 distinct institutions participated in the survey. Of these, 223 (89.6%) implemented at least 1 of the 4 supplemental reprocessing methods after MDRO outbreaks. Overall, 63% of centers used repeat HLD, 53% performed surveillance microbiological culturing, 35% used liquid chemical sterilization, and 12% used ethylene oxide sterilization. Thirty-seven centers (15%) routinely screened patients for MDRO. Forced-air drying after reprocessing was used by 47.8% of centers. Fifty percent of individual respondents, including 58.6% of physicians, believed that redesign of the duodenoscope is the best long-term reprocessing solution. The majority (55.1%) identified efficacy to be the single most important factor in selecting a reprocessing technique. Although most endoscopy centers have implemented enhanced duodenoscope reprocessing techniques, there is a large variation in practice. Most providers believe that duodenoscope redesign and identifying reprocessing techniques with maximal efficacy are the long-term priorities. Improved adherence to forced-air drying in duodenoscope reprocessing is needed.

Improper positioning of the elevator lever of duodenoscopes may lead to sequestered bacteria that survive disinfection by automated endoscope reprocessors

Some outbreaks associated with contaminated duodenoscopes have been attributed to biofilm formation. The objective of this study was to determine whether bacteria within an organic matrix could survive if the elevator lever was improperly positioned in the automated endoscope reprocessor (AER) after 1 round of reprocessing. Duodenoscope lever cavities with an open or sealed elevator wire channel were inoculated with 6-7 Log10 of both Escherichia coli and Enterococcus faecalis in ATS2015 (Healthmark Industries, Fraser, MI) and dried for 2 hours. The duodenoscopes with the lever in the horizontal position were processed through 2 makes of AERs. The cavity was sampled using a flush-brush-flush method to determine the quantity of surviving bacteria. E faecalis (range, 21-6 Log10 CFU) and E coli (range, 0-3 Log10 CFU) survived disinfection of sealed or unsealed elevator wire channel duodenoscopes in 2 different AERs with and without cleaning cycles. If bacteria in organic residue are under the improperly positioned lever, then just 1 round of use is sufficient for bacteria to survive both liquid chemical sterilization and liquid chemical HLD regardless of whether or not the AER had a cleaning cycle.

Clinical Issues— March 2017

Using one flexible endoscope for an upper and lower gastrointestinal (GI) endoscopy procedure Key words: flexible endoscope, esophagogastroduodenoscopy, colonoscopy, enteroscope, risk assessment. Enhanced methods for processing flexible duodenoscopes Key words: flexible duodenoscopes, liquid chemical sterilization, ethylene oxide sterilization, low-temperature sterilization, risk assessment. Modification of the Spaulding classification Key words: Spaulding classification, critical items, semicritical items, mucous membranes, risk assessment. Flushing flexible endoscope lumens with alcohol Key words: flexible endoscopes, isopropyl alcohol, ethyl alcohol, fixative, risk assessment. Using chlorine dioxide wipes for nonchanneled flexible endoscopes Key words: nonchanneled flexible endoscopes, high-level disinfectant, chlorine dioxide, risk assessment.

Effectiveness of the SYSTEM 1E Liquid Chemical Sterilant Processing System for reprocessing duodenoscopes

A troubling number of health care-acquired infection outbreaks and transmission events, some involving highly resistant microbial pathogens and resulting in serious patient outcomes, have been traced to reusable, high-level disinfected duodenoscopes in the United States. The Food and Drug Administration (FDA) requested a study be conducted to verify liquid chemical sterilization efficacy of SYSTEM 1E(®) Liquid Chemical Sterilant Processing System (STERIS Corporation, Mentor, OH) with varied duodenoscope designs under especially arduous conditions. Here, we describe the system's performance under worst case SYSTEM 1E(®) processing conditions. The test protocol challenged the system's performance by running a fractional cycle to evaluate reduction of recoverable test spores from heavily contaminated endoscopes, including all channels and each distal tip, under worst case SYSTEM 1E(®) processing conditions. All devices were successfully liquid chemically sterilized, showing greater than a 6 log10 reduction of Geobacillus stearothermophilus spores at every inoculation site of each duodenoscope tested, in less than half the exposure time of the standard cycle. The successful outcome of the additional efficacy testing reported here indicates that the SYSTEM 1E(®) is an effective low-temperature liquid chemical sterilization method for duodenoscopes and other critical and semicritical devices. It offers a fast, safe, convenient processing alternative while providing the assurance of a system expressly tested and cleared to achieve liquid chemical sterilization of specific validated duodenoscope models.

Disinfection and sterilization: An overview

All invasive procedures involve contact by a medical device or surgical instrument with a patient's sterile tissue or mucous membranes. The level of disinfection or sterilization is dependent on the intended use of the object: critical (items that contact sterile tissue such as surgical instruments), semicritical (items that contact mucous membrane such as endoscopes), and noncritical (devices that contact only intact skin such as stethoscopes) items require sterilization, high-level disinfection, and low-level disinfection, respectively. Cleaning must always precede high-level disinfection and sterilization.

Medical errors, infection-control breaches and the use of adulterated and misbranded medical devices

Several well-publicized cases of improper cleaning, disinfection or sterilization of contaminated reusable medical equipment that posed an increased risk of patientto-patient disease transmission were reported within the past few years, resulting in the notification of ap proximately 20 000 patients. These medical errors, the specific infection-control standards they breached, and assessments of the risk of infection associated with each are discussed. Other topics discussed include the Food and Drug Administration’s (FDA) regulation of medical devices and infection-control products; the use of adulterated, misbranded, and investigational devices; consent decrees and associated Certificates of Medical Necessity; and informed patient consent. Focus is placed on liquid chemical sterilization, its history, and the FDA’s recent censure and discontinuation of a medical device labeled with this claim, namely, the STERIS System 1 processor. Recommendations are provided for healthcare facilities, regulatory agencies, manufacturers of reusable medical devices, and professional healthcare organizations and administrations to improve public health and prevent healthcareassociated infections.

Comparison of liquid chemical sterilization with peracetic acid and ethylene oxide sterilization for long narrow lumens

The aim of this study was to determine how well peracetic acid liquid chemical sterilization (LCPAS) killed test organisms in the presence of 10% fetal bovine serum and 0.65% salt challenge (RPMI-S) compared with a 100% ethylene oxide (ETO) sterilizer and an ETO hydrochlorofluorocarbon (ETO-HCFC) sterilization method with long (125 cm), narrow (3-mm internal diameter) flexible lumens as the test carrier. The inoculated lumens were dried overnight before processing. The test organisms included Mycobacterium chelonei, Enterococcus faecalis, and Bacillus subtilis. For all 3 organisms tested, the LCPAS process resulted in a 6 log 10 reduction in bacterial load compared with a 2.5 log 10 to 6 log 10 reduction for the 100% ETO and ETO-HCFC sterilizers. Sterilization was achieved for 100%, 61%, and 67% of the lumen test carriers for the LCPAS, 100% ETO, and ETO-HCFC sterilizers, respectively. The data indicate that of the sterilization methods evaluated, LCPAS was the most effective for sterilizing narrow flexible lumens in the presence of residual inorganic and organic soil. This effectiveness was achieved through a combination of organism wash-off and peracetic acid sterilant killing of organisms. Salt was the major compounding factor for effective ETO gas sterilization, because carriers inoculated with organisms in 10% fetal bovine serum alone all were sterilized by both 100% ETO and ETO-HCFC sterilization methods. Our data support the critical need to ensure adequate precleaning of narrow flexible lumen endoscopes before any sterilization method. (AJIC Am J Infect Control 1998;26:469-77)

Technical and economic feasibility of reusing disposable perfusion cannulas

Objective(s): The reuse of disposable devices is a potential source of significant cost savings to hospitals. Venous and arterial perfusion cannulas under new and reused conditions were selected to identify the clinical, safety, technical, logistic, and economic issues that must be addressed to realize these savings. Methods: Single- and dual-stage venous and arterial cannulas from two manufacturers were tested when new, after initial clinical use, and after a single clinical use plus up to nine simulated reuses. Reuse was simulated by end-to-end bending, coupling and uncoupling of the connectors, and by two 1-hour soaks in plasma at 4° and 40° C, respectively. Cannulas were decontaminated and then processed by a peracetic acid-based liquid chemical sterilization system after each use/reuse. Sterilization was validated by eliminating Bacillus subtilis spores from the cannulas on each of five consecutive cycles. Cannulas were tested for physical changes, functional integrity, biocompatibility, and in vivo performance in sheep. A cost analysis was also performed. Results: Sterilization was successfully achieved. Mechanical changes were less than 20% on all variables studied and were undetectable by experienced cardiac surgeons in selective evaluation. No clinically important differences were found between new and reused cannulas, even after nine simulated reuses. Reusing cannulas four times would reduce the cost per procedure from $53 to $19 (64%). Conclusions: Preliminary data suggest that the perfusion cannulas tested can be safely and efficaciously used five times. Limited reuse of these disposable cannulas is technically feasible and cost-effective. Cannula reuse would result in a small incremental savings; however, with more expensive devices and higher-volume sterilization procedures, the savings could be considerably greater. This program provides a model for evaluation of other single-use medical devices for reuse. (J Thorac Cardiovasc Surg 1997;114:448-60)

Liquid Chemical Sterilization Using Peracetic Acid

Recurrent episodes of endoscope contamination with nontuberculous mycobacterium and Pseudomonas species, coupled with employee concerns about exposure to 2% glutaraldehyde and the requirement for rapid scope turnover time, led to the investigation of an alternative method for endoscope processing. A prospective evaluation of 220 bronchoscopy procedures was carried out. Endoscope culture surveillance was performed twice a month for a 12 month period on all endoscopes. In addition, the deliberate inoculation of bronchoscopes with Mycobacterium gordonae was carried out. No indications of cross contamination were noted among the 220 bronchoscopy procedures after processing the scopes by the studied liquid chemical sterilization system using peracetic acid. Ongoing patient surveillance did not reveal any indications of cross contamination for nearly 15,000 patients diagnostic or surgical endoscopic procedures using instruments processed by this liquid chemical sterilization system. Twice a month for 12 months, bronchoscopes, colonoscopes, and gastroscopes were cultured for bacterium, fungi, and acid fast bacilli and showed no growth. Deliberate inoculation of bronchoscopes with M. gordonae showed the scopes were rendered sterile. No unusual occurrences of occupational chemical exposure were found in 11 individuals working with this liquid chemical sterilization system. The peracetic acid based sterilization system studied proved to be an effective, safe, and economical alternative to the glutaraldehyde method.

Use of Biological Indicators Designed for Steam or Ethylene Oxide to Monitor a Liquid Chemical Sterilization Process

Use of Biological Indicators Designed for Steam or Ethylene Oxide to Monitor a Liquid Chemical Sterilization Process