Evaluation of the performance of rapid tests for screening carriers of acquired ESBL-producing Enterobacterales and their impact on turnaround time

Background: Extended-spectrum b-lactamase (ESBL)-producing Enterobacterales constitute a global burden for hospital infection, and the identification of carriers by screening patients at risk is recommended by several guidelines. Aim: To evaluate the impact of rapid ESBL tests on the turnaround time (TAT) of screening. Methods: Rectal swabs were analysed by culture and synergism tests for identification of non-Esherichia coli Enterobacterales that produce ESBLs (NEcESBL-producing Enterobacterales). The Rapid ESBL NP and NG CTX-M MULTI tests were performed on colonies grown on chromogenic media. The results of polymerase chain reaction and sequencing of ESBL genes were used as the gold standard. Results: Among 473 analysed swabs, 75 (15.9%) grew NEcESBL-producing Enterobacterales, leading to 89 isolates. Sensitivities of the synergism, Rapid ESBL NP and NG CTX-M MULTI tests were 0.97 [95% confidence interval (CI) 0.88-0.99], 0.81 (95% CI 0.69 -0.89) and 0.90 (95% CI 0.80-0.96), respectively. Specificities were 0.92 (95% CI 0.73 -0.99), 0.85 (95% CI 0.64-0.95) and 0.96 (95% CI 0.78-1.00), respectively. Considering the 473 rectal swabs, ESBL screening using the synergism, Rapid ESBL NP and NG CTX-M MULTI tests was calculated. Sensitivities were 0.96 (95% CI 0.86-0.99), 0.81 (95% CI 0.68-0.90) and 0.91 (95% CI 0.79-0.97); specificities were 1.00 (95% CI 0.98-1.00), 0.99 (95% CI 0.98 -1.00) and 1.00 (95% CI 0.99-1.00); positive predictive values were 0.96 (95% CI 0.86 -0.99), 0.94 (95% CI 0.81-0.98) and 1.00 (95% CI 0.91-1.00); and negative predictive values were 1.00 (95% CI 0.98-1.00), 0.98 (95% CI 0.96-0.99) and 0.99 (95% CI 0.97-1.00), respectively. When no NEcESBL-producing Enterobacterales were observed, the mean TAT was 30 h. When NEcESBL-producing Enterobacterales were identified, the mean TATs were 74.7, 38.0 and 36.7 h for the synergism, Rapid ESBL NP and NG CTX-M MULTI tests, respectively. Conclusion: The two rapid ESBL tests showed good performance and allowed a reduction in TAT for screening protocols to identify patients carrying ESBL-producing Enterobacterales. (C) 2020 The Authors. Published by Elsevier Ltd on behalf of The Healthcare Infection Society.

Automated summary

The study evaluated the impact of rapid ESBL tests on the turnaround time of screening, showing that the two rapid tests demonstrated good performance and could reduce the TAT in screening protocols to identify patients carrying ESBL-producing Enterobacterales.