Performance characteristics and optimal cut-off value of triple adenylate nucleotides test versus adenosine triphosphate test as point-of-care testing for predicting inadequacy of duodenoscope reprocessing

Abstract

Adenosine triphosphate (ATP) test based on one nucleotide has been applied as point-of-care testing (POCT) for bacterial contamination in the medical and food industries. Hypothetically, testing three adenylate nucleotides (A3) may provide better detection of duodenoscope bacterial contamination than ATP test. To evaluate performance characteristics and optimal cut-off value of A3 and ATP tests in predicting bacterial contamination of duodenoscopes. Four hundred duodenoscope samples obtained after 100 endoscopic retrograde cholangiopancreatography procedures were randomized into group A (A3 test) or B (ATP test). Samples were collected from the elevator at the four-step cleaning process of duodenoscope. We defined the new cut-off value of the test for reaching 100% negative predictive value (NPV) from our receiver operating characteristic (ROC). Using the cultures from the four-step cleaning process as the reference, the areas under ROC (AUROC) were 0.83 and 0.84 for group A (N= 200) and group B (N= 200), respectively. Using the cultures from post-high-level disinfection (HLD) as the reference, the AUROC were 0.35 and 0.74 for group A (N= 50) and group B (N= 50), respectively. We investigated ATP as a POCT after HLD with a new cut-off value of 40 RLU. However, this threshold did not allow detection of low numbers of bacteria. A3 and ATP tests provide good performances in predicting bacterial contamination of duodenoscopes for the four-step cleaning process. The ATP <40 RLU is helpful as a POCT after HLD; however, the limitation of this cut-off value is its inability to detect low numbers of bacteria.