MBT STAR^®-Carba IVD Kit by Bruker Daltonics

The first IVD certified mass spectrometric resistance detection assay

The MBT STAR-Carba IVD Kit (STAR – Selective Testing of Antibiotic Resistance) in conjunction with the MBT STAR-BL IVD software allows rapid microorganism identification and detection of carbapenemase activity in one workflow. This is the first mass spectrometric resistance detection assay expanding the application of the MALDI Biotyper MALDI-TOF mass spectrometry system in clinical microbiology beyond the identification of microorganisms.

Antimicrobial resistance – a major health care threat

Unnecessary prescription of antibiotics, treatment of diseases with broad-spectrum antibiotics and the excessive use of antibiotics in agriculture lead to the emergence of multi-resistant bacteria. Only a few last resort antibiotics are left of which carbapenems are of highest importance. These drugs can be deactivated by bacterial carbapenemase enzymes. To avoid their further spread in hospitals, fast and cost-effective methods for detection of bacteria with active carbapenemases are in high demand.

The MBT STAR-Carba Assay principle

The Kit utilizes Imipenem as the benchmark carbapenem antibiotic. Bacteria from overnight cultures or positive blood cultures are incubated in an Imipenem solution. Bacteria with active carbapenemase will inactivate Imipenem by hydrolysation of the ß-lactam ring, which is associated with a mass shift.

A fast and simple workflow

In assays with bacteria without active carbapenemase only peaks corresponding to the intact antibiotic will be present in the mass spectrum. In assays with bacteria with active carbapenemase, peaks of the intact antibiotic will decrease. The intensity ratio of hydrolysed to intact antibiotic signals indicates the level of carbapenemase activity. 
The MBT STAR-BL IVD Software Module monitors this activity on acquired mass spectra of aliquots of the co-incubation solution (incubation for 30/60 minutes) by automatic calculation of the intact Imipenem intensity and corresponding ratio hydrolysed / non-hydrolysed. Results are normalized to signal intensities from positive and negative control strains and displayed as a color-coded plot as shown below.

What is the MBT STAR-Carba Assay good for?

The MBT STAR-Carba Assay is designed for rapid detection of prevalent Class A, B or D carbapenemase activity in Gram-negative Enterobacteriaceae, Pseudomonas spp. and Acinetobacter spp. It can be used for microorganisms derived from culture plates and optionally for microorganisms isolated from positive blood cultures after isolation of cells using the MBT Sepsityper IVD Kit. The assay allows to rapidly identify bacteria and their carbapenemase activity on the MALDI Biotyper IVD platform in one workflow.