Sa1041 PERFORMANCE CHARACTERISTICS AND OPTIMAL CUT-OFF VALUE OF ADENOSINE TRIPHOSPHATE TESTING FOR RAPID EVALUATION OF BACTERIAL CONTAMINATION AFTER REPROCESSING DUODENOSCOPES

Abstract

Recently, there have been many reports on carbapenem-resistant bacterial contamination of the duodenoscope after reprocessing, thus surveillance cultures (SC) for bacterial contamination (BC) from the elevator site (ES) and the working channel (WC) is recommended before the duodenoscope can be returned to use. However, the main limitation is the delay in culture result. The adenosine triphosphate (ATP) test is a process of rapidly measuring actively growing microorganisms through detection of ATP. To date, ATP test is widely used in the food and beverage industry, but its use in endoscope reprocessing is still scarce. We aimed to determine the performance characteristics (PC) and optimal cut-off value (CV) of ATP test to predict culture positivity of BC for duodenoscopes after high-level disinfection (HLD). All 50 used duodenoscopes (TJF-Q180V, Olympus, Tokyo, Japan) underwent standard reprocessing and were enrolled during September-November 2017. After the single HLD, culture samples (CS) were collected from the ES by swab rotation and from WC by purging with 20 mL of sterile water and tested for Relative Light Units (RLU) by Clean-Trace Surface ATP (3M Health Care Ltd, Berkshire, UK). We evaluated the PC (sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), false positive rate (FPR), and accuracy of ATP test on the recommended 200 RLU and other CVs by using the receiver operating characteristic (ROC) curve guidance. After the HLD, the median ATP level from the ES and the WC were 83 RLU (range 20-1325 RLU) and 54 RLU (range 8-436 RLU), respectively. Of 50 CS, 9 (18%) CS from the ES were positive for BC (Klebsiella pneumoniae = 6, Escherichia coli = 2, and Morganella morgagni =1) whereas all CS from the WC had negative culture results. Of 9 positive CS, 8 (89%) CS were obtained from the same duodenoscope which later found with a tiny foreign body near the ES seen by a microscope and a pinhole damage at 20 mm from the distal end of the scope. While 6 of 9 positive CS showed ATP ≥ 200 RLU (range 201-713 RLU), the remaining positive scopes (n=3) demonstrated ATP < 200 RLU (range 47-153 RLU). When using the ROC curve analysis from the ES compared with the culture results (figure1), the area under the ROC was 0.72. Given the following data on the PC for each ATP level (table 1), we proposed the ATP level of 40 RLU as the optimal CV with 100% sensitivity, 100% NPV and 80.5% FPR for BC rapid screening test after duodenoscope reprocessing. ATP test has a potential use as a rapid indicator of duodenoscope cleanliness after HLD reprocessing and the routine SC with delay in result may be omitted. If ATP ≥ 40 RLU, the duodenoscope needs to be returned for more cycles of HLD. The duodenoscope with repetitive high RLU on each surveillance may require an inspection for ES defective.Tabled 1Performance characteristics of ATP from the elevator sites compared with culturesDuodenoscope partATP cut-off (RLU)Sensitivity (%)Specificity (%)PPV (%)NPV (%)False positive rate (%)Accuracy (%)Elevator4010019.521.410080.534.05088.939.024.294.161.048.06088.941.525.094.458.550.07088.946.326.795.053.754.08077.853.726.991.746.358.09077.861.030.492.639.064.010077.863.431.892.936.666.015077.865.933.393.134.168.020066.778.040.091.422.076.0 Open table in a new tab