Next Generation Antibiotic Susceptibility Testing (NGAST)

Abstract

Antimicrobial Resistance (AMR) is a worldwide issue that needs to be tackled. The lack of a rapid tool for the detection of antimicrobial resistance is needed. Recently Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry (MALDI-TOF MS) have revolutionized the routine clinical labs for the bacterial identification with providing rapid, accurate and reliable results within hours in comparison to the conventional methods of detections. Also, MALDI-TOF MS seems to have the potentiality to be used as an antibiotic susceptibility testing tool. In recent times, one of the developed testings to detect AMR by this MS-platform. MALDI is the MALDI Biotyper antibiotic susceptibility test rapid assay (MBT-ASTRA). In this project, The MBT-ASTRA was used for testing bug-drug combination from preliminary studies to validate the robustness of this technique on a MALDI-TOF MS (AB SCIEX). 4 strains of Klebsiella pneumoniae and P. aeruginosa (including 2 sensitive strains and 2 resistant strains for each bug) were tested against 64μg/ml of meropenem with an incubation time of one and two hours respectively. Also, Escherichia coli was tested against Ciprofloxacin at a concentration of 32μg/ml with two hours of an incubation. Secondly, the project also involved in optimizing four new bug-drug combinations which included E. coli against colistin and gentamicin and P. aeruginosa against gentamicin and ciprofloxacin. The results from the testing showed a clear discrimination between the different strains. As well as a significant discrimination for E. coli against gentamicin within one hour of an incubation time at a concentration of 64μg/ml. This study demonstrates the ability of the MBT-ASTRA in the rapid detection of AMR.