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Fight against antibiotic resistance: two additional rapid lateral flow immuno-assays

Researchers at the LERI (SPI / DMTS), together with the AP-HP, have developed two rapid and inexpensive immunological tests to detect antibiotic resistance. The novelty: the tests detect the activity of bacterial enzymes that hydrolyze extended-spectrum cephalosporins.

Published on 2 August 2022

Antimicrobial resistance

In recent years, the emergence of multi-resistant bacteria has accelerated, in particular due to the excessive use of antibiotics. Among them, extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae are of particular concern. Indeed, each year, these bacteria are responsible for 19% of hospital-acquired infections in the United States and also are associated with increased mortality and healthcare costs, according to the U.S. government agency Centers for Disease Control and Prevention (CDC).

Aware of the stakes, researchers from the LERI (SPI/DMTS) have developed a recognized expertise in the development of test strips detecting CTX-M ESBLs, responsible for the inactivation by hydrolysis of extended-spectrum cephalosporins (ESC) such as cefotaxime (CTX). These strains were targeted because they emerged explosively in the 1990s and now represent 98% of ESBL in France.


Among the tests developed, the CTX-M MULTI test, marketed by the NG-Biotechcompagny, has already proved its worth in 2017 (see news of November 13, 2017). It can simultaneously detect CTX-M groups 1, 2, 8, 9 and 25. In a recent study, the test showed sensitivity and specificity above 98% on a collection of enterobacteria colonies already characterized (by PCR) for their beta-lactamase content. The same results were obtained with colonies and blood cultures derived from clinical samples containing enterobacteria (see news of November 19, 2020). Despite this excellent performance, the CTX-M-MULTI test may not detect some very rare enzymes. To overcome this shortcoming, SPI together with an AP-HP team has recently developed another type of strip test, the LFIA-CTX test, based on the detection not of the bacterial enzyme responsible for the hydrolysis of the antibiotic but of the hydrolysis itself (cefotaxime)[1]

Recently, researchers have developed another test strip, named LFIA Rapid ESC, which combines the two previous tests [2]. It is very efficient and inexpensive (less than 15 euros), and displays its results rapidly, i.e. within 10 minutes after a 30-minute incubation, and also offers 100% sensitivity and specificity.

Contact CEA-Joliot :

Hervé Volland (

Beta-lactams (β-lactams) are a broad class of antibiotics that include penicillin derivatives, cephalosporins, and carbapenems. Beta-lactams are the most commonly used antibiotics.
Extended spectrum cephalosporins (ESCs) are a newer class of cephalosporins that act on a broad spectrum of bacteria resistant to other antibiotics.
 Cefotaxime (CTX) is a 3rd generation cephalosporin.
 Beta-lactamases are enzymes produced by certain bacteria that degrade (by hydrolysis) beta-lactam antibiotics. They thus confer resistance to bacteria that synthesize them.
Extended-spectrum beta-lactamases (ESBLs) generate resistance to most beta-lactam antibiotics.

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