Assessment on Experimental Bacterial Biofilms and in Clinical Practice of the Efficacy of Sampling Solutions for Microbiological Testing of Endoscopes

Abstract

Opinions differ on the value of microbiological testing of endoscopes, which varies according to the technique used. We compared the efficacy on bacterial biofilms of sampling solutions used for the surveillance of the contamination of endoscope channels. To compare efficacy, we used an experimental model of a 48-h Pseudomonas biofilm grown on endoscope internal tubing. Sampling of this experimental biofilm was performed with a Tween 80-lecithin-based solution, saline, and sterile water. We also performed a randomized prospective study during routine clinical practice in our hospital sampling randomly with two different solutions the endoscopes after reprocessing. Biofilm recovery expressed as a logarithmic ratio of bacteria recovered on bacteria initially present in biofilm was significantly more effective with the Tween 80-lecithin-based solution than with saline solution (P ‫؍‬ 0.002) and sterile water (P ‫؍‬ 0.002). There was no significant difference between saline and sterile water. In the randomized clinical study, the rates of endoscopes that were contaminated with the Tween 80-lecithin-based sampling solution and the saline were 8/25 and 1/25, respectively (P ‫؍‬ 0.02), and the mean numbers of bacteria recovered were 281 and 19 CFU/100 ml (P ‫؍‬ 0.001), respectively. In conclusion, the efficiency and therefore the value of the monitoring of endoscope reprocessing by microbiological cultures is dependent on the sampling solutions used. A sampling solution with a tensioactive action is more efficient than saline in detecting biofilm contamination of endoscopes.

Effectiveness of current disinfection procedures against biofilm on contaminated GI endoscopes

“…In regard to ATP levels, post-cleaning were comparable with pre-contamination results. After contamination, ATP levels reached a median of 8434 (range: 1385-727668) RLUs, whereas after cleaning levels decreased to 35 (range: 11-220) RLUs, comparable with the pre-contamination levels of 28 (21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40) RLUs. After cleaning, only one catheter displayed more than 100 RLUs (220 RLUs,…”

“…Previous studies with the same biofilm model, tried to mimic endoscope catheters by using Teflon tubes, and sampling was performed by preparing isolated small parts from each tube, for subsequent analysis by electronic microscopy 15,24 . In contrast, our flow-model protocol consisted of full-length endoscope channels, from which we removed biofilm from a continuous segment of 15 cm length of each catheter.…”

“…bolletii (INCQS 594) biofilms were produced over 5 and 15 days, respectively, within 12 original channels of GI endoscopes (Olympus Medical Systems, Nishi-Shinjuku-ku, Tokyo, Japan), as adapted from previously described models 24,25 . The sterile endoscope channels were connected to two 500 mL bags, one of them with 300 mL of culture medium and 10 5 CFU/mL of microorganisms, M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT forming a closed system (Figure 1).…”

Is peracetic acid suitable for the cleaning step of reprocessing flexible endoscopes?

“…Under natural environmental conditions, biofilms are likely to be composed of a mixture of different species [131,132] . In the laboratory, they can be grown on various materials and devices, including polystyrene microtitre plates [133][134][135][136] , haemolysis glass tubes [137,138] , stainless steel coupons [134,139] and also in Teflon tubes [140][141][142][143] , similar to endoscope channels.…”

A new buildup biofilm model that mimics accumulation of material in flexible endoscope channels

“…Overall, the rate of infections attributed to transfer of infectious agents from contaminated endoscopes is low but recent publications have demonstrated that these rates may be higher than previously thought as there is poor documentation and reporting of such events (Ofstead et al, 2010). In the past few years there has been world-wide documentation of outbreaks associated with antibiotic-resistant organisms due to contaminated flexible endoscopes (Aumeran et al, 2012;Carbonne et al, 2010), with recent USA outbreaks attributed to transmission of carbapenem-resistant Enterobacteriaceae (CRE) arising from endoscopic retrograde cholangiopancreatography (ERCP) procedures (Wonderf et al, 2015;Ubhayawardana et al, 2013;Epstein et al, 2014). It has been difficult to understand the documented survival of microorganisms in flexible endoscopes despite repeated rounds of reprocessing using manufacturer validated cleaning and disinfection methods which should preclude biofilm development.…”