Method for assessing the microbial contamination of GI endoscopes

We read with interest the article regarding endoscope storage time after reprocessing. The statement suggested that endoscopes can be stored for as long as 21 days after standard reprocessing with low risk of pathogenic microbial colonization. Only 4 isolates represented potential pathogens (4.2% of 96 sites tested), and all were found in low concentrations. The authors’ results were consistent with those of previous studies that evaluated endoscope contamination using a similar method of sampling. However, the contamination rate is very low compared with those observed in French studies.^,  We wonder whether the observed differences could be due to the technique of sampling. The autors used sterile water to irrigate the channels of the endoscopes. In France, the guidelines recommend sampling endoscopes by injecting 120 mL neutralizing pharmacopoeia diluent buffer with sodium thiosulfate into the channels using sterile connectors. A two-way channel irrigation is made systematically to improve the efficiency of sampling. The solution is recovered at the distal end of the endoscope, and each collected sample is incubated at 30°C on plate count agar after filtration of 100 mL of the solution on 0.45-μm filters. The aim of this technique of sampling is to pick up biofilms, to neutralize the peracetic acid, and to enable the growth of bacteria, which may be present in the endoscope’s channels. It is possible that the use of sterile water does not achieve the same quality of sampling. Moreover, the amount of fluid analyzed is much lower than that recommended in France. This is why we believe that the level of colonization of the endoscopes may be underestimated by use of the sampling technique described in this study. We believe that further studies should be conducted to confirm these results, which may be very interesting.