Higher yield in duodenoscope cultures collected with addition of neutralizing agent

Endoscope processing effectiveness: A reality check and call to action for infection preventionists and clinicians

BACKGROUND

Flexible endoscopes are heavily exposed to blood, mucus, and other secretions during procedures and may harbor billions of microbes before processing. Guidelines recommend thorough cleaning and sterilization or high-level disinfection (HLD) after each use.

METHODS

This review describes evidence on the effectiveness of HLD from a robust review of peer-reviewed journals, adverse events reports posted by the Food and Drug Administration, and other government reports published during 2019-2024.

RESULTS

Although HLD theoretically eliminates viruses, fungi, and bacteria (except a few resilient spores), numerous studies found it did not reliably eliminate microbes in real-world settings, and a large proportion of endoscopes harbored substantial bioburden and potential pathogens. Dozens of endoscopy-associated outbreaks have been reported in the past 5years, including several involving multidrug-resistant organisms. When contaminated endoscopes or endoscopy-associated infections were discovered, investigators commonly found that personnel were skipping essential steps or doing them improperly.

DISCUSSION

To reduce infection risk and enhance patient safety, infection preventionists, clinicians, sterile processing and departmental managers, and other leaders should review the evidence, perform risk assessments, and implement proactive strategies for quality improvement in their facilities.

Contaminated duodenoscopes in ERCP: sensitivity of detection and risk of underdetection

BACKGROUND AND AIMS

Periodic duodenoscope cultures are essential to timely detect contamination, but their sensitivity remains unknown. This study aims to determine the sensitivity of duodenoscope cultures and to estimate the prevalence of contaminated duodenoscope use.

METHODS

We combined duodenoscope microbiologic surveillance data from March 2015 to June 2022 with usage data to evaluate patient exposure to duodenoscopes contaminated with microorganisms of gut or oral origin (MGO). We identified duodenoscopes with repeated species-level contamination within a year and used molecular typing to confirm genetic relatedness. Genetically related microorganisms over multiple duodenoscope cultures of a single duodenoscope indicated a period of sustained contamination, and a cluster was defined as overlapping periods of sustained contamination between different duodenoscopes. If microorganisms were not available for molecular analysis, we marked the period as unconfirmed. A sample was defined as false negative if it did not show the target microorganism(s) in a period of sustained contamination. We used 3 scenarios to hypothesize about contaminated use and culture sensitivity.

RESULTS

We included 556 duodenoscope cultures with 185 (33.3%) contaminated with MGO. The total usage of duodenoscopes was 5226. We identified 1 period of sustained contamination, 6 unconfirmed periods, and 2 clusters. Depending on our scenario assumptions, the percentage of contaminated use varied from 12.3% to 23.7% and culture sensitivity ranged from 82.2% to 98.9%.

CONCLUSIONS

Limited sensitivity of duodenoscope cultures leads to improper clearance of duodenoscopes for clinical use, increasing risks of outbreaks. The applicability of a single culture to end a duodenoscope's quarantine should be re-evaluated.

Evaluation of plasma activated liquids for the elimination of mixed species biofilms within endoscopic working channels

The use of reusable flexible endoscopes has increased dramatically over the past decade, however despite improvements in endoscope reprocessing, the continued emergence of endoscopy-associated outbreaks as a result of multi-drug resistant bacteria has highlighted the need for a new approach to disinfection. Here, the use of plasma activated liquids (PALs) for the elimination of mixed species biofilm contamination within the working channels of endoscopes was evaluated. Cold atmospheric pressure plasma was used to chemically activate water and a commercially available pH buffered peracetic acid to create PALs. Polytetrafluoroethylene endoscope surrogate test pieces were contaminated with clinically relevant mixed species biofilms. The efficacy of PALs for the decontamination of narrow lumens was compared against the commercial disinfectant. Plasma activation was found to increase the antibiofilm capabilities of pH buffered peracetic acid by introducing reactive chemical species into the solution. Disinfection of endoscopic test pieces with plasma activated disinfectant (PAD) resulted in a 7.30 log10 reduction of biofilm contamination in 5 min, surpassing the 4.39 log10 reduction observed with the currently used endoscope disinfection method. PAD also resulted in reduced regrowth and recolonization of the surface of the endoscopic test pieces. Minimal changes to the surface morphology and composition were observed following exposure to PAD in comparison to the commercial disinfectant, suggesting the developed approach is no more aggressive than current disinfection approaches.

Comparison of Sampling Methods for Detecting Protein in Gastrointestinal Endoscopes

Background: Persistent microbial contamination of flexible endoscopes has been linked to infections and outbreaks. Valid and reliable sampling methods are critical for monitoring processing effectiveness in flexible endoscopes. In this study, the effectiveness of protein extraction via turbulent fluid flow (TFF) sampling was compared with flush-only sampling in manually cleaned gastrointestinal endoscopes. Methods: A crossover study design, in which both sampling methods were used in alternating order during each endoscope encounter, was utilized to assess protein levels after colonoscopes and gastroscopes underwent manual cleaning. Endoscope channels were sampled with 20 mL sterile water using TFF and flush-only methods. Protein levels were quantified using a spectrophotometer. Results: Protein samples were collected during a total of 40 encounters with 20 unique endoscopes (19 colonoscopes and 21 gastroscopes) following procedural use. More effluent was captured following TFF (20-30 mL) compared with flush-only (19-21 mL) sampling. Zero samples had detectable protein after flush-only sampling, and nine samples (22.5%; two gastroscopes and seven colonoscopes) had detectable protein following TFF sampling (range 1-4 μg/mL). Of those, four exceeded the 2 μg/mL study threshold for recleaning after the first cleaning and three of four dropped to 2 μg/mL or less after recleaning. Conclusion: TFF sampling of the entire suction-biopsy channel allowed the detection of residual protein in nine gastrointestinal endoscopes, whereas no protein was detected in samples obtained by manually flushing the instrument channel. More research is needed to characterize the real-world utility of using the TFF system to verify whether soil and bioburden have been effectively removed during processing. Numerous studies have documented that a majority of fully processed, patient-ready endoscopes harbor microbes.1-8 Microbes found in endoscopes include high-concern organisms (e.g., multidrug-resistant microbes and pathogens) that have been linked to endoscopy-associated outbreaks.9-12 In these outbreaks, visible residual soil was discovered during the outbreak investigation. Current guidelines and standards note that effectively cleaning endoscopes is critical to the success of high-level disinfection (HLD) and sterilization.13,14 Several studies by Ofstead and colleagues6,15,16 have documented high protein levels on endoscopes. A study involving colonoscopes and gastroscopes detected protein on 100% of manually cleaned endoscopes (range 3-11 μg/mL).6 Other studies also found protein in 100% of manually cleaned bronchoscopes (range 2-30 μg/mL) and sterilized ureteroscopes (range 9-32 μg/mL).15,16 These contamination levels were higher than positive controls, which were dirty gastroscopes that had not been manually cleaned. Microbes were found on 12.5% to 60% of fully processed endoscopes, including potential pathogens such as Pseudomonas aeruginosa, Escherichia coli, and Micrococcus luteus.6,15,16 This reinforces the need to verify that endoscopes are clean prior to undergoing HLD or sterilization. Evidence shows that protein can persist through multiple rounds of cleaning.17,18 Despite efforts to clean the endoscope, harvesting samples from surfaces that remain contaminated with soil can be challenging because sampling commonly uses the same tools as cleaning (e.g., brushes or swabs and flushing). Residual soil or bioburden may also be encased in a biofilm matrix that has been hardened through exposure to harsh chemicals used during HLD and/or sterilization and repeated cycles of drying,19,20 thereby increasing the difficulty of capturing a sample. Hervé et al.21 noted that protein deposits in endoscopes were able to resist brushing and flushing, especially in the presence of wear and damage. Historically, flush-only ("flush") sampling was used,22,23 but this method often was limited to the instrument channel and captured lower yields compared with more robust methods.4,24,25 As the effectiveness of sampling affects the validity of results of tests for organic soil and microbial cultures, more robust sampling methods may be required.26 Guidance on sampling for microbial cultures provided by the Food and Drug Administration (FDA) and Centers for Disease Control and Prevention (CDC) involves incorporating a brushing step and an additional flushing step ("flush-brush-flush") to dislodge and flush out microbes.27 This method has been found to be more effective than flush sampling,3,24 but brushes cannot access every endoscope channel and may leave behind bristles. Researchers have reported that the FDA/CDC sampling method is cumbersome, time consuming,28 and prone to contamination.7 Even when using recommended sampling methods, investigators have reported needing to rely on external experts and destructive sampling to effectively harvest samples that ultimately revealed the outbreak pathogen.10,11 This underscores the importance of robust sampling methods, both to avoid false negatives from failing to capture soil or bioburden that is present and to avoid false positives from environmental contamination.7,29 Given the challenges associated with current sampling techniques for organic soil testing and microbial cultures, this study was conducted to evaluate a method that could potentially improve sample validity and reduce the influence of human factors on sampling. The automated turbulent fluid flow (TFF) system pumps a mixture of air and water through the suction and instrument channels from the suction connector to the distal end and into a sterile collection cup that is sealed during sampling to maintain a closed system. The turbulent flow provides friction to endoscope interior surfaces without needing to use a brush.30 In this study, protein extraction via TFF sampling was compared with flush sampling in manually cleaned gastrointestinal endoscopes.

Endoscope sampling and culturing methods

BACKGROUND

Contamination rates reported in the literature for patient-ready flexible endoscopes vary from 0.4% to 49%. Unfortunately, the comparison and interpretation of these results is almost impossible since several factors including sampling and culturing methods, target levels for contamination, or definition of indicator micro-organisms vary widely from one study to the other.

AIM

To compare the efficacy of six duodenoscope sampling and culturing methods by means of extraction efficacy comparison, while at the same time identifying key parameters that provide optimal microbial recovery.

METHODS

The duodenoscope sample extraction efficacy of each method was assessed using the repetitive recovery method described in ISO 11737-1: 2018.

FINDINGS

Mean overall bioburden extraction efficacy varied from 1% for the Australian method to 39% for the French one. The lowest endoscope sample extraction efficacy was associated with the absence of any neutralizer, friction, or tensioactive agent, and when only a small portion of the sampling solution collected was inoculated on to culture media. The efficacy of the sampling and culturing methods also varied according to the nature of micro-organisms present in the endoscope, and the time between sampling and culturing.

CONCLUSION

This study supports the need for a harmonized and standardized sampling and culturing method for flexible endoscopes.

Fluid retention in endoscopes: A real-world study on drying effectiveness

BACKGROUND

Outbreaks linked to inadequate endoscope drying have infected numerous patients, and current standards and guidelines recommend at least 10 minutes of forced air for drying channels. This study evaluated a new forced-air drying system (FADS) for endoscopes.

METHODS

Drying was assessed using droplet detection cards; visual inspection of air/water connectors, suction connectors, and distal ends; and borescope examinations of endoscope interiors. Assessments were performed after automated endoscope reprocessor (AER) alcohol flush and air purge cycles and after 10-minute FADS cycles.

RESULTS

Researchers evaluated drying during encounters with 22 gastroscopes and 20 colonoscopes. After default AER alcohol and air purge cycles, 100% (42/42) of endoscopes were still wet. Substantial fluid emerged from distal ends during the first 15 seconds of the FADS cycle, and droplets also emerged from air/water and suction connectors. Following FADS cycle completion, 100% (42/42) were dry, with no retained fluid detected by any of the assessment methods.

CONCLUSIONS

Multiple endoscope ports and channels remained wet after AER cycles intended to aid in drying but were dry after the FADS cycle. This study reinforced the need to evaluate the effectiveness of current drying practices and illustrated the use of practical tools in a real-world setting.

A search strategy for detecting duodenoscope-associated infections: a retrospective observational study

BACKGROUND

Duodenoscope-associated infections (DAIs) are exogenous infections resulting from the use of contaminated duodenoscopes. Though numerous outbreaks of DAI have involved multidrug-resistant micro-organisms (MDROs), outbreaks involving non-MDROs are also likely to occur. Detection challenges arise as these infections often resolve before culture or because causative strains are not retained for comparison with duodenoscope strains.

AIM

To identify and analyse DAIs spanning a seven-year period in a tertiary care medical centre.

METHODS

This was a retrospective observational study. Duodenoscope cultures positive for gastrointestinal flora between March 2015 and September 2022 were paired with duodenoscope usage data to identify patients exposed to contaminated duodenoscopes. Analysis encompassed patients treated after a positive duodenoscope culture and those treated within the interval from a negative to a positive culture. Patient identification numbers were cross-referenced with a clinical culture database to identify patients developing infections with matching micro-organisms within one year of their procedure. A 'pair' was established upon a species-level match between duodenoscope and patient cultures. Pairs were further analysed via antibiogram comparison, and by whole-genome sequencing (WGS) to determine genetic relatedness.

FINDINGS

Sixty-eight pairs were identified; of these, 21 exhibited matching antibiograms which underwent WGS, uncovering two genetically closely related pairs categorized as DAIs. Infection onset occurred up to two months post procedure. Both causative agents were non-MDROs.

CONCLUSION

This study provides crucial insights into DAIs caused by non-MDROs and it highlights the challenge of DAI recognition in daily practice. Importantly, the delayed manifestation of the described DAIs suggests a current underestimation of DAI risk.

Double phage displayed peptides co-targeting-based biosensor with signal enhancement activity for colorimetric detection of Staphylococcus aureus

The development of simple, fast, sensitive, and specific strategies for the detection of foodborne pathogenic bacteria is crucial for ensuring food safety and promoting human health. Currently, detection methods for Staphylococcus aureus still suffer from issues such as low specificity and low sensitivity. To address this problem, we proposed a sensitivity enhancement strategy based on double phage-displayed peptides (PDPs) co-targeting. Firstly, we screened two PDPs and analyzed their binding mechanisms through fluorescent localization, pull-down assay, and molecular docking. The two PDPs target S. aureus by binding to specific proteins on its outer membrane. Based on this phenomenon, a convenient and sensitive double PDPs colorimetric biosensor was developed. Double thiol-modified phage-displayed peptides (PDP-SH) enhance the aggregation of gold nanoparticles (AuNPs), whereas the specific interaction between the double PDPs and bacteria inhibits the aggregation of AuNPs, resulting in an increased visible color change before and after the addition of bacteria. This one-step colorimetric approach displayed a high sensitivity of 2.35 CFU/mL and a wide detection range from 10-2 × 108 CFU/mL. The combination with smartphone-based image analysis improved the portability of this method. This strategy achieves the straightforward, highly sensitive and portable detection of pathogenic bacteria.