Sterile Reverse Osmosis Water Combined with Friction Are Optimal for Channel and Lever Cavity Sample Collection of Flexible Duodenoscopes

Many bacterial species have been found to exist in a viable but non-culturable (VBNC) state since its discovery in 1982. VBNC cells are characterized by a loss of culturability on routine agar, which impairs their detection by conventional plate count techniques. This leads to an underestimation of total viable cells in environmental or clinical samples, and thus poses a risk to public health. In this review, we present recent findings on the VBNC state of human bacterial pathogens. The characteristics of VBNC cells, including the similarities and differences to viable, culturable cells and dead cells, and different detection methods are discussed. Exposure to various stresses can induce the VBNC state, and VBNC cells may be resuscitated back to culturable cells under suitable stimuli. The conditions that trigger the induction of the VBNC state and resuscitation from it are summarized and the mechanisms underlying these two processes are discussed. Last but not least, the significance of VBNC cells and their potential influence on human health are also reviewed.

Patient-ready endoscopes were monitored over an 80-week period to determine the efficacy of decontamination procedures in a busy endoscopy center. Decontamination failure was related to patient and procedural parameters. Samples from patient-ready endoscopes were cultured aerobically and anaerobically and subjected to polymerase chain reaction (PCR) to detect hepatitis B virus (HBV), hepatitis C virus (HCV), and HIV. PCR to detect coliforms from 109 culture negative washes was used as a surrogate marker for biofilm in endoscopes. PCR was used to detect the presence of Helicobactor pylori in endoscopes used on infected patients. Procedural information such as biopsy retrieval, endoscope number, diagnosis, attending personnel, and decontamination system procedures was collected. Gastroscopes (n = 1,376) and colonoscopes (n = 987) were equally contaminated (1.8% vs 1.9%, respectively) with low numbers of organisms commonly isolated from the nasopharynx and/or feces. Only 1 wash contained viral nucleic acid (HCV). There was a significant correlation (P < .001) between the number of times a patient-ready endoscope was contaminated and its frequency of use. Colonoscopes used on patients with gastrointestinal disease were significantly more likely to remain contaminated through the decontamination process (P < .05). All other patient, staff, and decontamination system parameters remained not statistically significant. Coliform DNA was detected in 40% of culture-negative washes collected from patient-ready endoscopes, suggesting the presence of biofilm. No H pylori DNA was detected. Recommended decontamination procedures do not entirely eliminate persistence of low numbers of organisms on a few endoscopes, but this is unlikely to cause serious consequences in patients. Bacterial biofilm is difficult to remove and may explain this low-level persistence.

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.