Addition Of Neutralizer To Duodenoscope Samples Increases Yield Of Cultures Acquired After High Level Disinfection

Aims A reliable culturing method is necessary to properly monitor contamination of duodenoscopes. The CDC advises addition of neutralizers to culture samples to neutralize remaining detergents or disinfectants. However, evidence that this method promotes appropriate outcomes of culturing and circumvents false negative results is not available. This study compares the yield of cultures with and without addition of a neutralizer.

Methods We found two brand new duodenoscopes of the same type (DEC ED34-i10T2, Pentax) to show persistent contamination after they were subjected to simulated ERCP procedures with an artificial test soil (ATS2015, Healthmark) containing a very high concentration (10^8 CFU/mL) of gut flora. The soiling was followed by manual cleaning, high level disinfection (HLD) and overnight storage in a drying cabinet. Samples of duodenoscope 1 were collected after HLD or drying and samples of duodenoscope 2 were collected at both points. Sampling included a swab of the distal tip and a flush-brush-flush of the working channel. Only samples of duodenoscope 2 were supplemented with Dey-Engley neutralizing broth.

Results Duodenoscope 1 completed 70 tests (38 samples after HLD, 32 after drying). Duodenoscope 2 completed 60 tests. Of duodenoscope 2, significantly (P< 0,001) more samples collected immediately after HLD were positive compared to samples of duodenoscope 1, respectively 57 (95 %) and 3 (7.9 %). There was no significant difference in samples collected after drying, 23 (71.9 %) positive tests in duodenoscope 1 and 49 (81.7 %) in duodenoscope 2 (P = 0.278).

Conclusions The difference in yield of samples collected directly after HLD is likely due to false negative cultures in those samples not treated with neutralizers. No increased yield was found in samples collected with or without a neutralizer after overnight storage. Neutralizers should be added to samples collected of wet duodenoscopes to avoid false negative culture results. Neutralizers are not needed when sampling dried duodenoscopes.

Citation Kwakman J, Bruno M, Vos M. eP515 ADDITION OF NEUTRALIZER TO DUODENOSCOPE SAMPLES INCREASES YIELD OF CULTURES ACQUIRED AFTER HIGH LEVEL DISINFECTION. Endoscopy 2021; 53: S269.

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Artikel online veröffentlicht:
19. März 2021