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Frequently Asked Questions (FAQs) on the Interim Duodenoscope Surveillance Protocol

Why were the following protocols developed?

The sample and culture protocols were released as part of the larger CDC Interim Duodenoscope Surveillance Protocol as a guide for facilities considering cultures of duodenoscopes to assess the adequacy of their duodenoscope reprocessing. Although there is no requirement to perform duodenoscope cultures, some facilities have elected to perform regular surveillance cultures as part of their response to the issue. This is not a replacement for ongoing training and oversight to ensure that cleaning and disinfection steps are performed correctly; however, it does provide facilities considering cultures with a consistent starting point for a protocol that can be adapted for use.

How does the recent FDA announcement of a validated cleaning protocol impact the use of these procedures?

On March 26, 2015, FDA released a Medical Device Safety Communicationand updated the Infections Associated with Reprocessed Duodenoscope webpage to announce that Olympus, one of the three manufacturers of this type of device, has provided validated new reprocessing instructions for Model TJF-Q180V duodenoscopes [PDF - 13 pages] and that all facilities using this particular model of duodenoscope should follow these new instructions as soon as possible. When followed correctly, there is a high degree of assurance that the reprocessing instructions effectively clean and disinfect this model of duodenoscope. These new instructions are specific to the Olympus Model TJF-Q180V; facilities with other models of duodenoscopes should continue to use the manufacturer’s current reprocessing instructions. Endoscope reprocessing is labor intensive and human errors can lead to inadequate reprocessing and bacterial transmission from the device; the surveillance testing can be used as a quality assurance monitor of that process. It is strongly suggested that until there is further evidence that duodenoscopes can be consistently reprocessed in a manner that eliminates contamination of the duodenoscope and prevents transmission of pathogens, the role for post-reprocessing microbiologic surveillance remains.

Are the protocols meant to assure sterility of the duodenoscope before use?

This testing is not meant to assure sterility of the duodenoscope. The duodenoscopes must pass through the mouth and upper gastrointestinal tract, both of which normally contain a rich array of microorganisms, during use; thus, these devices are categorized as semi-critical and are required to undergo a minimum of high level disinfection after cleaning, but are not necessarily sterile. Residual organisms of low-concern may be present on a duodenoscopes, and may vary depending on the reprocessing, handling, and culturing practices in a facility. Refer to the CDCs Interim Duodenoscope Surveillance Protocol (algorithm options listed as flow diagrams at the end of the webpage) for specific details when viable bacteria are detected.

What is the purpose of the sampling and culture protocols?

The sampling protocol is intended to extract bacteria from the distal end and instrument channel of a duodenoscope. Use of a brush premoistened with phosphate buffered saline (0.01M) with 0.02% Tween®-80 solution (PBST) provides physical and chemical mechanisms to detach bacteria from scope surfaces, and the flush with sterile RO water rinses out bacteria out for subsequent culture. The culture protocol is intended to provide two options for detection of bacteria: both a qualitative and a quantitative method are described, the choice of which to use is up to the discretion of the facility.

What duodenoscopes have been tested using these protocols?

The Olympus duodenoscopes, models TJF-160VF and TJF-Q180V, were evaluated using similar protocols in recent outbreak investigations.

Why is Streptococcus sp. viridans group listed as high-concern organisms in the Interim Duodenoscope Surveillance Protocol?

Viridans streptococci were included as an example of an organism of concern because these organisms can cause disease and would be unlikely to be the result of contamination of environmental cultures. All the organisms of concern listed could be found in the GI tract of a hospitalized patient, so presence of any of them would potentially indicate failure of reprocessing. The list of organisms was based on expert review and could be modified as more information becomes available.

Will the sampling and culture protocols be validated?

CDC is discussing next steps for validating the surveillance protocol with the wider community including FDA, professional societies, and other stakeholders.

Who should be trained to collect the duodenoscope samples?

We recommend two individuals collect samples from the duodenoscope. Samples should be collected by personnel familiar with the instrument, e.g. personnel who routinely reprocess or handle the instrument. The personnel must be capable of using aseptic technique to collect the samples required for culture. A reprocessing technician or an infection control professional could be trained on the sampling protocol and demonstrate qualification to collect duodenoscope samples from the distal end and instrument channel, as well as a microbiology technician if appropriate. Each facility should use discretion in determining who is the best qualified for performing duodenoscope sampling.

What type of room or location should be used for duodenoscope sampling?

Duodenoscopes should be sampled on a clean surface away from traffic, obvious airflow (e.g. vents), and potential contamination with water. A sectioned-off area of a reprocessing room or a separate room can be designated for duodenoscope sampling.

Are there alternative buffers to PBST?

The interim protocol provides one buffer option for duodenoscope sampling at the distal end and instrument channel. Phosphate buffered saline (0.01M) with 0.02% Tween®-80 solution (PBST) was chosen due to the gentle buffering capacity of the saline and the mild detergent characteristics of Tween®-80, which should aid in the detachment of bacteria from the duodenoscope during the brushing step. PBST can also be made in a laboratory by combining PBS and a polysorbate-80 solution to indicated final concentrations, and following the manufacturers’ recommendations for sterile filtration of the liquids at an elevated temperature.

Normal saline and other alternate buffers with similar characteristics to PBST have been used by researchers, as seen in peer-reviewed scientific literature. However, a comparison of the various buffers for recovery efficiency has not been done.

Are the samples intended to be clinical samples?

These samples are from a medical device, not clinical/ patient samples. The CDC guideline on the Environmental Infection Control in Healthcare Facilities says that microbiologic sampling for quality assurance purposes can be conducted by healthcare facilities to evaluate sterilization processes or evaluation of the impact of infection control processes.

Who should perform the processing, culture, and identification of resultant bacteria from the samples collected?

Samples should be processed by personnel with microbiological understanding of culturing principles and identification of common environmental and clinical bacteria. Facilities should use discretion in determining personnel best qualified and trained for these activities. A multi-disciplinary team should be brought together to decide the best approach for the individual facility. The facility can consider using an external laboratory for the laboratory protocol (e.g. academic environmental microbiology laboratory associated with the hospital or private contract laboratory, etc.) if necessary.

What are the limitations of these methods?

The protocols are not yet validated, i.e., the sensitivity, specificity and limits on quantitation or detection are not established for all organisms. Professional gastrointestinal societies, as well as other partners, have also called for the manufacturers of both endoscopic ultrasound (EUS) and duodenoscopes to participate in validation of the sampling protocol for their devices. In addition, the focus of this protocol is on recovery of “high-concern” organisms rather than measuring overall bioburden or organisms of lower pathogenic potential; interpretation of negative and positive results are discussed in the protocol.

Is a HLD neutralizer needed for duodenoscope samples prior to culture?

Whether or not a disinfectant neutralizer improves the yield of duodenoscope cultures is not clear, as the published literature shows contradictory findings. Some studies have not used neutralizers for culture-based surveillance studies of endoscopes after reprocessing (Alfa et al. 2002, 2012, 2013, 2014; Moses and Lee 2003). Overall, there is minimal literature demonstrating the use of a neutralizer during the processing of flexible endoscope samples. Culture methods from specialty societies and/or government agencies outside the United States do not mention the use of neutralizers (Queensland Government 2011; Public Health Agency of Canada 2010 [PDF - 107 pages]). In contrast, three studies specific to endoscopes (Miner et al. 2012) and clinical materials (Lerones et al. 2004) show that certain disinfectant residuals can have biocidal activity and/or cytotoxicity (Ryu et al. 2013) that might impact the yield of surveillance cultures.

Further, guidance documents state that residual disinfectant levels should be reduced to safe, non-toxic levels through the rinsing steps during proper reprocessing before procedures are conducted (FDA 2015; ANSI/AAMI 2015; AAMI 2014) with validation of the rinsing instructions to appropriately do so (FDA 2015). These statements are subject to interpretation. Each type of high level disinfectant (HLD) should be used according to manufacturer’s recommendations, following the defined number and type of post-disinfection rinses. Due to the impact of a disinfectant neutralizer on the yield of duodenoscope cultures being unclear, we suggest that facilities should consider the following options: (a) include an internal process positive control (e.g. gram-positive such as Staphylococcus aureus or gram negative such as Escherichia coli) in an aliquot of the flush sample (5 ml) and process accordingly with duodenoscope samples (see the CDC Interim Duodenoscope Culture Method for details) and/or (b) measure residuals after reprocessing to determine whether a neutralizer should be utilized, which will be dependent on the duodenoscopes manufacturer and recommended HLD (i.e. water soluble or not water soluble).

Neutralizers of common disinfectant chemicals, from the Clinical Microbiology Procedures Handbook (Bond and Sehulster 2004, Table 13.10-3) should be referenced for considerations of using a neutralizer when duodenoscopes are to be sampled.

Where can I find more information, guidelines, and recommendations regarding flexible gastrointestinal reprocessing?

Please refer to the specific manufacturer’s instructions and the following:

Can facilities use an automated microbial detection system for culturing samples?

Facilities with an automated microbial detection system within their clinical laboratories could consider using these systems as part of the CDC Interim Duodenoscope Culture Method , Culture Method A – Presence/ Absence by Enrichment. Specifically, after samples are concentrated by centrifugation (Step 4), it is reasonable to use an automated microbial detection system if appropriate media type, optimal volume, and incubation temperature are aligned with the CDC Interim Duodenoscope Culture Method , Culture Method A – Presence/ Absence by Enrichment to determine if bacteria are present. It is important to note that facilities should communicate with the manufacturer regarding the sample components, as well as run controlled samples or conduct side-by-side comparisons with a known culture method before implementing an automated microbial detection system for duodenoscope surveillance. Facilities should continue to follow the algorithm as described in the CDC Interim Duodenoscope Surveillance Protocol to adjudicate the results.


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