2142. Comparison of Molecular-Based vs. Conventional Culture-Based Screening Methods for Detection of Carriers of Extended-Spectrum β-Lactamases (ESBL) and Carbapenemases-Producing Enterobacteriacae (CPE)

BACKGROUND: Active surveillance and contact precautions may prevent cross-transmission of ESBL-producing Enterobacteriaceae and CPE. Culture-based methods delaying results might increase risk of cross-transmission, and lead to unnecessary preemptive contact precautions. This observational cohort study compared rapid Loop-Mediated Isothermal Amplification (LAMP) assays to conventional culture-based methods for ESBL and CPE screening of critically ill patients. METHODS: This study was conducted in the adult ICUs at Geneva University Hospitals. We collected consecutive rectal ESwabs routinely performed, either for admission screening of high-risk patients or once weekly routine screening of all patients hospitalized in the ICU. Eazyplex® SuperBug CRE system (Amplex Biosystems) assays were performed directly on rectal Eswabs according to the manufacturer’s instructions. For the conventional culture-based method, we used chromID® ESBL agar (ESBL) coupled with chromID®OXA-48. Discordant specimens were retested using disk diffusion tests and the same LAMP assay on isolates. Microbiological turn-around times (TAT; from the reception in the laboratory to result notification) were collected. RESULTS: Overall, 290 rectal ESwabs were analyzed. ESBL and CPE prevalence were 16.7% and 1.0%, respectively. Three discordant isolates could not be further investigated and considered as LAMP false positive. Adjusted analytical performances were for CPE: 100% (95IC 100–100%) sensitivity, 99.6% (99.0–100%) specificity, 75% (32.6–100%) PPV, and 100% (100–100%) NPV, and for ESBL: 85% (73.9–96.1%) sensitivity, 98.8% (97.4–100%) specificity, 91.9% (83.1–100%) PPV, and 97.6% (95.7–99.5%) NPV. A decrease in TAT was observed when comparing LAMP screening assay against conventional method (50.3 hours vs. 6.2 hours; Figure 1). Figure 2 shows time reductions comparing both screening strategies. CONCLUSION: Screening strategies based on LAMP could fasten discontinuation of unnecessary pre-emptive isolation time for patients at risk and earlier implementation of contact precautions for previously unknown carriers of ESBL or CPE. [Image: see text] [Image: see text] DISCLOSURES: All authors: No reported disclosures.