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

D.S Blanc,F Poncet,B Grandbastien,G Greub,L Senn,P Nordmann

doi:10.1016/j.jhin.2020.10.013

D.S Blanc, F Poncet + Show 4 more

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https://doi.org/10.1016/j.jhin.2020.10.013

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Abstract

Extended-spectrum β-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. To evaluate the impact of rapid ESBL tests on the turnaround time (TAT) of screening. 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. 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 30h. When NEcESBL-producing Enterobacterales were identified, the mean TATs were 74.7, 38.0 and 36.7h for the synergism, Rapid ESBL NP and NG CTX-M MULTI tests, respectively. The two rapid ESBL tests showed good performance and allowed a reduction in TAT for screening protocols to identify patients carrying ESBL-producing Enterobacterales.

Highlights

The management of extended-spectrum beta-lactamase (ESBL)-producing Enterobacterales is currently a major clinical problem worldwide [1], with national prevalence rates ranging from 10% to 60% [2e4]
This study shows that the introduction of such tests in the ESBL screening procedure enabled a reduction in turnaround time (TAT) of at least 24 h
As direct culture does not always provide sufficient isolated colonies to use the recommended inoculum of two 10-mL loops for the Rapid ESBL NP test, this study evaluated if a single colony would be sufficient

Summary

Introduction

The management of extended-spectrum beta-lactamase (ESBL)-producing Enterobacterales is currently a major clinical problem worldwide [1], with national prevalence rates ranging from 10% to 60% [2e4]. Escherichia coli is the main reservoir of ESBLs, mainly spreads in the community, and is very rarely the source of nosocomial outbreaks [2]. Nosocomial outbreaks of ESBL-producing Enterobacterales are mainly associated with Klebsiella pneumoniae, Enterobacter cloacae and Enterobacter aerogenes, and are reported worldwide [2]. Several national guidelines, including Swiss [7] and French [8] guidelines, recommend the identification of carriers by screening patients at risk, and isolating patients carrying non-Esherichia coli Enterobacterales that produce ESBLs (NEcESBL-producing Enterobacterales). The rationale to isolate patients carrying NEcESBL-producing Enterobacterales alone is that E. coli has lower ability to spread between patients than other ESBL-producing Enterobacterales [6]

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