A fluorogenic biotracer for reliable detection of staphylococcal beta-lactamase: towards improved precision therapy in severe MSSA infections
Abstract
BACKGROUND AND OBJECTIVES: Accurate detection of staphylococcal beta-lactamase remains a diagnostic challenge, despite its importance for guiding antibiotic therapy, particularly in severe infections, such as endocarditis and bacteraemia. Currently, no available method reliably detects beta-lactamase activity in all staphylococcal species. Here, we evaluated a novel fluorogenic biotracer, 352600-C (MOLSID, Lyon, France), designed to detect beta-lactamase activity in staphylococci. METHODS: The 352600-C biotracer was incorporated into Mueller-Hinton agar plates onto which staphylococcal strains were subcultured at 37°C. Colony fluorescence was assessed at 4, 6 and 24 h using a 365 nm UV lamp. The assay was performed on a large collection of blaZ-positive (n = 124, including BlaZ types A, B, C and D) and blaZ-negative (n = 69) staphylococci from 18 species (Staphylococcus aureus, n = 100; S. non-aureus, n = 93). Molecular detection of the blaZ gene using WGS served as the gold standard. Phenotypic susceptibility to penicillins was also tested using EUCAST recommendations. RESULTS: After 4, 6 and 24 h of incubation, the assay showed sensitivities of 92.2%, 96.9% and 100% for S. aureus and 50.0%, 88.3% and 100% for non-aureus staphylococci, respectively. None of the 69 blaZ-negative strains produced fluorescent colonies (specificity 100%). Notably, the assay detected all BlaZ types. Penicillin disc diffusion showed 98.4% sensitivity and 77.8% specificity for MSSA. CONCLUSIONS: This novel assay for the detection of staphylococcal beta-lactamase demonstrated simplicity, rapidity and excellent accuracy after 24 h incubation (100% sensitivity and specificity) across a genetically diverse and representative collection of clinical isolates, making it a valuable tool for routine diagnostics and antimicrobial stewardship.
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BibTeX
@article{dupieux2026fluorogenic,
title = {{A fluorogenic biotracer for reliable detection of staphylococcal beta-lactamase: towards improved precision therapy in severe MSSA infections}},
author = {Céline Dupieux and Patricia Martins Simoes and Benjamin Youenou and François Vandenesch and Anne Tristan and Frédéric Laurent},
journal = {Journal of Antimicrobial Chemotherapy},
year = {2026},
month = sep,
doi = {10.1093/jac/dkag268},
url = {https://hal.science/hal-05781324v1},
note = {CC BY},
}
RIS
TY - JOUR
TI - A fluorogenic biotracer for reliable detection of staphylococcal beta-lactamase: towards improved precision therapy in severe MSSA infections
AU - Céline Dupieux
AU - Patricia Martins Simoes
AU - Benjamin Youenou
AU - François Vandenesch
AU - Anne Tristan
AU - Frédéric Laurent
PY - 2026
DA - 2026/09/04
JO - Journal of Antimicrobial Chemotherapy
DO - 10.1093/jac/dkag268
UR - https://hal.science/hal-05781324v1
AB - BACKGROUND AND OBJECTIVES: Accurate detection of staphylococcal beta-lactamase remains a diagnostic challenge, despite its importance for guiding antibiotic therapy, particularly in severe infections, such as endocarditis and bacteraemia. Currently, no available method reliably detects beta-lactamase activity in all staphylococcal species. Here, we evaluated a novel fluorogenic biotracer, 352600-C (MOLSID, Lyon, France), designed to detect beta-lactamase activity in staphylococci. METHODS: The 352600-C biotracer was incorporated into Mueller-Hinton agar plates onto which staphylococcal strains were subcultured at 37°C. Colony fluorescence was assessed at 4, 6 and 24 h using a 365 nm UV lamp. The assay was performed on a large collection of blaZ-positive (n = 124, including BlaZ types A, B, C and D) and blaZ-negative (n = 69) staphylococci from 18 species (Staphylococcus aureus, n = 100; S. non-aureus, n = 93). Molecular detection of the blaZ gene using WGS served as the gold standard. Phenotypic susceptibility to penicillins was also tested using EUCAST recommendations. RESULTS: After 4, 6 and 24 h of incubation, the assay showed sensitivities of 92.2%, 96.9% and 100% for S. aureus and 50.0%, 88.3% and 100% for non-aureus staphylococci, respectively. None of the 69 blaZ-negative strains produced fluorescent colonies (specificity 100%). Notably, the assay detected all BlaZ types. Penicillin disc diffusion showed 98.4% sensitivity and 77.8% specificity for MSSA. CONCLUSIONS: This novel assay for the detection of staphylococcal beta-lactamase demonstrated simplicity, rapidity and excellent accuracy after 24 h incubation (100% sensitivity and specificity) across a genetically diverse and representative collection of clinical isolates, making it a valuable tool for routine diagnostics and antimicrobial stewardship.
SN - 0305-7453
SN - 1460-2091
ER -