Study on carbapenemase-producing bacteria by matrix-assisted laser desorption/ionization approach

Area of Science:

• Microbiology
• Biochemistry
• Clinical Diagnostics

Background:

• Rising carbapenem resistance poses a global health threat.
• Matrix-assisted laser desorption/ionization (MALDI) is a reliable method for carbapenemase detection.
• Further analysis of the MBT STAR-Carba assay's robustness and applications is needed.

Purpose of the Study:

• To evaluate the MBT STAR-Carba assay for pre-characterizing carbapenemase classes in Enterobacterales and P. aeruginosa.
• To assess the assay's performance with varying suspension densities and incubation times.
• To test the assay's utility in characterizing metallo-β-lactamases (MBL) using inhibition assays.

Main Methods:

• Utilized the MBT STAR-Carba assay with modified parameters (suspension density, incubation time).
• Performed inhibition assays to analyze metallo-β-lactamase activity.
• Tested on Enterobacterales and P. aeruginosa strains.

Main Results:

• The assay demonstrated high sensitivity in detecting carbapenemase hydrolytic activity.
• It successfully enabled partial classification of carbapenemase classes.
• Optimized high-density suspensions reduced incubation time to 1 minute for some strains.
• The assay effectively investigated inhibitor effects on MBL activity.

Conclusions:

• The MBT STAR-Carba assay is a sensitive tool for carbapenemase detection and partial classification.
• Optimized parameters enhance its speed and applicability.
• The assay shows significant discriminatory potential beyond routine detection, serving as a susceptibility assay for MBLs.