Turbulent fluid flow is a novel closed-system sample extraction method for flexible endoscope channels of various inner diameters

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.

Contaminated flexible endoscopes: Review of impact of channel sampling methods on culture results and recommendations for root-cause analysis

Recently, infection transmission risk associated with contaminated, patient-ready flexible endoscopes has attracted attention. Outbreaks of multidrug-resistant organisms resulting in infection and/or colonization have been particularly concerning. Recent CDC and FDA recommendations focus on reducing "exogenous" infection transmission and specifically recommend that endoscopy sites have quality systems in place for endoscope reprocessing. Another key recommendation is the culture of patient-ready endoscopes to detect contamination with organisms of concern. Remaining gaps in the guidelines include ensuring that optimal endoscope-channel sample methods are used and ensuring effective root-cause analysis and remediation when contamination is detected. In this review, we summarize the critical aspects of endoscope sample collection and present a practical approach to root-cause analysis and remedial action plans.

A narrative review on current duodenoscope reprocessing techniques and novel developments

Duodenoscopy-associated infections occur worldwide despite strict adherence to reprocessing standards. The exact scope of the problem remains unknown because a standardized sampling protocol and uniform sampling techniques are lacking. The currently available multi-society protocol for microbial culturing by the Centers for Disease Control and Prevention, the United States Food and Drug Administration (FDA) and the American Society for Microbiology, published in 2018 is too laborious for broad clinical implementation. A more practical sampling protocol would result in increased accessibility and widespread implementation. This will aid to reduce the prevalence of duodenoscope contamination. To reduce the risk of duodenoscopy-associated pathogen transmission the FDA advised four supplemental reprocessing measures. These measures include double high-level disinfection, microbiological culturing and quarantine, ethylene oxide gas sterilization and liquid chemical sterilization. When the supplemental measures were advised in 2015 data evaluating their efficacy were sparse. Over the past five years data regarding the supplemental measures have become available that place the efficacy of the supplemental measures into context. As expected the advised supplemental measures have resulted in increased costs and reprocessing time. Unfortunately, it has also become clear that the efficacy of the supplemental measures falls short and that duodenoscope contamination remains a problem. There is a lot of research into new reprocessing methods and technical applications trying to solve the problem of duodenoscope contamination. Several promising developments such as single-use duodenoscopes, electrolyzed acidic water, and vaporized hydrogen peroxide plasma are already applied in a clinical setting.

Hydrodynamics and surface properties influence biofilm proliferation

A biofilm is an interface-associated colloidal dispersion of bacterial cells and excreted polymers in which microorganisms find protection from their environment. Successful colonization of a surface by a bacterial community is typically a detriment to human health and property. Insight into the biofilm life-cycle provides clues on how their proliferation can be suppressed. In this review, we follow a cell through the cycle of attachment, growth, and departure from a colony. Among the abundance of factors that guide the three phases, we focus on hydrodynamics and stratum properties due to the synergistic effect such properties have on bacteria rejection and removal. Cell motion, whether facilitated by the environment via medium flow or self-actuated by use of an appendage, drastically improves the survivability of a bacterium. Once in the vicinity of a stratum, a single cell is exposed to near-surface interactions, such as van der Waals, electrostatic and specific interactions, similarly to any other colloidal particle. The success of the attachment and the potential for detachment is heavily influenced by surface properties such as material type and topography. The growth of the colony is similarly guided by mainstream flow and the convective transport throughout the biofilm. Beyond the growth phase, hydrodynamic traction forces on a biofilm can elicit strongly non-linear viscoelastic responses from the biofilm soft matter. As the colony exhausts the means of survival at a particular location, a set of trigger signals activates mechanisms of bacterial release, a life-cycle phase also facilitated by fluid flow. A review of biofilm-relevant hydrodynamics and startum properties provides insight into future research avenues.