First evaluation of the biotracer developed by MOLSID SAS, Lyon, France, for the detection of staphylococcal beta-lactamase
This bioproject is related to the strains' collection tested for the study below. Background and objectives. Accurate detection of staphylococcal beta-lactamase remains a diagnostic challenge, despite its crucial impact in guiding antibiotic therapy, particularly in severe infections such as endocarditis and bacteraemia. Currently, no available method can reliably detect beta-lactamase activity in all staphylococcal species.  In this study, we report the clinical evaluation of a novel fluorogenic biotracer, 352600-C (MOLSID, Lyon, France), designed to detect beta-lactamase activity in staphylococcal isolates. 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) and blaZ-negative (n=69) staphylococci from 18 species (S. aureus, n=100; S. non-aureus, n=93). Molecular detection of the blaZ gene served as the gold standard. 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, yielding a specificity of 100%. Notably, the assay successfully detected all BlaZ types. Conclusion. This novel assay for the detection of staphylococcal beta-lactamase demonstrated simplicity, rapidity, and excellent accuracy (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.
This bioproject is related to the strains' collection tested for the study below. Background and objectives. Accurate detection of staphylococcal beta-lactamase remains a diagnostic challenge, despite its crucial impact in guiding antibiotic therapy, particularly in severe infections such as endocarditis and bacteraemia. Currently, no available method can reliably detect beta-lactamase activity in all staphylococcal species.  In this study, we report the clinical evaluation of a novel fluorogenic biotracer, 352600-C (MOLSID, Lyon, France), designed to detect beta-lactamase activity in staphylococcal isolates. 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) and blaZ-negative (n=69) staphylococci from 18 species (S. aureus, n=100; S. non-aureus, n=93). Molecular detection of the blaZ gene served as the gold standard. 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, yielding a specificity of 100%. Notably, the assay successfully detected all BlaZ types. Conclusion. This novel assay for the detection of staphylococcal beta-lactamase demonstrated simplicity, rapidity, and excellent accuracy (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.
Molecular Genetics and Genomics Medicine