RESIST CTX-M

Comparison of three immunochromatographic assays for the rapid detection of CTX-M in Enterobacterales.

Maurin E, Mallecot E, Beyrouthy R, Bonnet R, Robin F.
Eur J Clin Microbiol Infect Dis. 2025 Nov 4. doi: 10.1007/s10096-025-05337-9

Abstract
Purpose: Two lateral flow immunochromatographic assays are currently available for the rapid detection of CTX-M enzymes in Enterobacterales, RESIST CTX-M (Coris BioConcept, Gembloux, Belgium) and NG-Test CTX-M MULTI (NG Biotech, Guipry, France). The NG-Test CTX-M MULTI is designed to detect all CTX-M enzymes. The RESIST CTX-M detects CTX-M from the M-15 and the M-14 group for V1.0, CTX-M from the M-15 and the M-14/M-8 groups for V1.1.
Method: The performances of the two versions of the RESIST CTX-M test (V1.0 and V1.1) and the NG-Test CTX-M MULTI were assessed against a collection of 140 non-redundant Enterobacterales isolates characterized for their content in β-lactamases. β-lactamases content was established from genotypic analysis to collect a broad diversity of resistance mechanisms and bacterial strains, including 74 ESBL-producing strains (CTX-M (n = 56), other ESBLs (n = 18) either alone or associated with other β-lactamases), 22 strains overproducing chromosomal AmpC, 13 strains producing plasmid-encoded AmpC, 7 carbapenemase-producing strains, 3 strains combining the production of several β-lactamases other than ESBL and 21 strains that produced other β-lactamases.
Results: The sensitivity and specificity of NG-Test CTX-M MULTI for detecting CTX-M were 98.2% and 85.7%, respectively. They were 87.2% and 93.5% for RESIST CTX-M V1.0 for CTX-M of the M-1 and M-9 groups versus 94.3% and 93.1% for RESIST CTX-M V1.1 for CTX-M of the M-1 and M-9/8 groups.
Conclusion: Lateral flow immunochromatographic assays are rapid and reliable tests for the detection of CTX-M production. The NG-Test CTX-M MULTI and RESIST CTX-M V1.1 were the most efficient. However, one limitation of the different assays is the risk of false-positive results with strains belonging to the K. oxytoca and C. farmeri/sedlakii/amalonaticus complexes, which overproduce their chromosomal β-lactamase.

https://pubmed.ncbi.nlm.nih.gov/41186667/

P0545– Development of a rapid diagnostic test for identification of group 1 and group 9 CTX-M β-Lactamases

Gilleman Q, Debière S, Nazé F, Avrain L, Nizet Y, Bouzet J, Denorme L and Mertens P
33th European Congress of Clinical Microbiology and Infectious Diseases, Infectious Diseases April 15 – 18, 2023.
Poster

P05211 – Comparison of two immunochromatographic tests for the detection of CTX-M ESBL on clinical isolates at the Belgian National Reference Centre

Bogaerts P, Mbundu Lukukula C, Bouchahrouf W, Berhin C, Montesinos I, Denis O, Liesse Iyamba JM and Te-Din Huang TD
33th European Congress of Clinical Microbiology and Infectious Diseases, Infectious Diseases April 15 – 18, 2023.
Poster