Prospective assessment of the effectiveness of standard high-level disinfection for echoendoscopes.

BACKGROUND AND AIMS: Duodenoscopes have been implicated in the transmission of multidrug-resistant organisms (MDROs). Echoendoscopes could potentially transmit infection. The aim of this study was to assess the effectiveness of standard high-level disinfection (HLD) for radial and linear echoendoscopes and to compare it with that of duodenoscopes. METHODS: We performed a prospective single-center study sampling echoendoscopes immediately before use, from the working channel (radial and linear echoendoscopes) and the transducer (radial echoendoscope) or elevator mechanism and transducer (linear echoendoscope). The primary outcome was the proportion of echoendoscopes with any culture showing ≥1 MDRO; secondary outcomes included bacterial growth >0 colony forming units (CFUs) and ≥10 CFUs on either sampling location. We compared these findings with duodenoscope cultures from the previously published DISINFECTS trial. RESULTS: During the study period, 101 echoendoscopes were sampled (n = 50 radial echoendoscopes, n = 51 linear echoendoscopes). No MDROs were recovered. Bacterial growth >0 CFUs was noted in 6% and ≥10 CFUs in 3% of all echoendoscopes. There was no significant difference in growth between radial and linear echoendoscopes (P = .4 for >0 CFU growth; P = .6 for ≥10 CFUs growth). The proportion of transducer and/or elevator mechanism positive for bacterial growth was significantly higher in duodenoscopes as compared with echoendoscopes (P = .02). CONCLUSIONS: After standard HLD, no echoendoscope showed MDRO growth, 6% showed >0 CFUs, and 3% showed ≥10 CFUs bacterial growth. Bacterial growth was higher in duodenoscopes at the level of the transducer and/or elevator mechanism when compared with echoendoscopes.

Randomized Comparison of 3 High-Level Disinfection and Sterilization Procedures for Duodenoscopes.

BACKGROUND AND AIMS: Duodenoscopes have been implicated in the transmission of multidrug-resistant organisms (MDRO). We compared the frequency of duodenoscope contamination with MDRO or any other bacteria after disinfection or sterilization by 3 different methods. METHODS: We performed a single-center prospective randomized study in which duodenoscopes were randomly reprocessed by standard high-level disinfection (sHLD), double high-level disinfection (dHLD), or standard high-level disinfection followed by ethylene oxide gas sterilization (HLD/ETO). Samples were collected from the elevator mechanism and working channel of each duodenoscope and cultured before use. The primary outcome was the proportion of duodenoscopes with an elevator mechanism or working channel culture showing 1 or more MDRO; secondary outcomes included the frequency of duodenoscope contamination with more than 0 and 10 or more colony-forming units (CFU) of aerobic bacterial growth on either sampling location. RESULTS: After 3 months of enrollment, the study was closed because of the futility; we did not observe sufficient events to evaluate the primary outcome. Among 541 duodenoscope culture events, 516 were included in the final analysis. No duodenoscope culture in any group was positive for MDRO. Bacterial growth of more than 0 CFU was noted in 16.1% duodenoscopes in the sHLD group, 16.0% in the dHLD group, and 22.5% in the HLD/ETO group (P = .21). Bacterial growth or 10 or more CFU was noted in 2.3% of duodenoscopes in the sHLD group, 4.1% in the dHLD group, and 4.2% in the HLD/ETO group (P = .36). MRDOs were cultured from 3.2% of pre-procedure rectal swabs and 2.5% of duodenal aspirates. CONCLUSIONS: In a comparison of duodenoscopes reprocessed by sHLD, dHLD, or HLD/ETO, we found no significant differences between groups for MDRO or bacteria contamination. Enhanced disinfection methods (dHLD or HLD/ETO) did not provide additional protection against contamination. However, insufficient events occurred to assess our primary study end-point. ClinicalTrials.gov no: NCT02611648.

Duodenoscope hang time does not correlate with risk of bacterial contamination.

BACKGROUND: Current professional guidelines recommend a maximum hang time for reprocessed duodenoscopes of 5-14 days. We sought to study the association between hang time and risk of duodenoscope contamination. METHODS: We analyzed cultures of the elevator mechanism and working channel collected in a highly standardized fashion just before duodenoscope use. Hang time was calculated as the time from reprocessing to duodenoscope sampling. The relationship between hang time and duodenoscope contamination was estimated using a calculated correlation coefficient between hang time in days and degree of contamination on the elevator mechanism and working channel. RESULTS: The 18 study duodenoscopes were cultured 531 times, including 465 (87.6%) in the analysis dataset. Hang time ranged from 0.07-39.93 days, including 34 (7.3%) with hang time ≥7.00 days. Twelve cultures (2.6%) demonstrated elevator mechanism and/or working channel contamination. The correlation coefficients for hang time and degree of duodenoscope contamination were very small and not statistically significant (-0.0090 [P = .85] for elevator mechanism and -0.0002 [P = 1.00] for working channel). Odds ratios for hang time (dichotomized at ≥7.00 days) and elevator mechanism and/or working channel contamination were not significant. CONCLUSIONS: We did not find a significant association between hang time and risk of duodenoscope contamination. Future guidelines should consider a recommendation of no limit for hang time.

Adenosine Triphosphate Quantification Correlates Poorly with Microbial Contamination of Duodenoscopes.

OBJECTIVE The aim of this study was to quantify the correlation between adenosine triphosphate (ATP) measurements and bacterial cultures from duodenoscopes for evaluation of contamination following high-level disinfection. DESIGN Duodenoscopes used for any intended endoscopic retrograde cholangiopancreatography (ERCP) procedure were included. Microbiologic and ATP data were collected concomitantly and in the same manner from ERCP duodenoscopes. SETTING A high-volume endoscopy unit at a tertiary referral acute-care facility. METHODS Duodenoscopes were sampled for ATP and bacterial contamination in a contemporaneous and highly standardized fashion using a "flush-brush-flush" method for the working channel (WC) and a dry flocked swab for the elevator mechanism (EM). Specimens were processed for any aerobic bacterial growth (colony-forming units, CFU). Growth of CFU>0 and ATP relative light unit (RLU)>0 was considered a contaminated result. Frequency of discord between among WC and EM measurements were calculated using 2×2 contingency tables. The Spearman correlation coefficient was used to calculate the relatedness of bacterial contamination and ATP as continuous measurements. RESULTS The Spearman correlation coefficient did not demonstrate significant relatedness between ATP and CFU for either a WC or EM site. Among 390 duodenoscope sampling events, ATP and CFU assessments of contamination were discordant in 82 of 390 WC measurements (21%) and 331 of 390 of EM measurements (84.9%). The EM was frequently and markedly positive by ATP measurement. CONCLUSION ATP measurements correlate poorly with a microbiologic standard assessing duodenoscope contamination, particularly for EM sampling. ATP may reflect biological material other than nonviable aerobic bacteria and may not serve as an adequate marker of bacterial contamination. Infect Control Hosp Epidemiol 2017;38:678-684.