MALDI-TOF mass spectrometry technology for detecting biomarkers of antimicrobial resistance: current achievements and future perspectives

The laboratory diagnosis of infections is based on pathogen identification and antimicrobial susceptibility determination. The gold standard of cultivation, isolation and susceptibility testing is a time-consuming procedure and in some cases this can be threatening for patients' outcome. In the current review the applications of mass spectrometry in pathogen identification and especially in detecting biomarkers of antimicrobial resistance are analyzed. MALDI-TOF (matrix-assisted laser desorption/ionization time-of-flight) mass spectrometry is a new technology that has revolutionized pathogen identification and has also proven to accelerate detection of antimicrobial resistance compared to the traditional antibiotic susceptibility tests (AST) as well as DNA amplification methodologies. The technology has incorporated up to know four different methodologies: (I) the detection of differences of mass spectra of susceptible and resistant isolates of a given microorganism using the classical strain typing methodology; (II) the analysis of bacterial induced hydrolysis of β-lactam antibiotics; (III) the detection of stable (non-radioactive) isotope-labeled amino acids; and (IV) the analysis of bacterial growth in the presence and absence of antibiotics using an internal standard. The implementation of MALDI-TOF methodologies has improved detection of resistance in aerobic, Gram-positive and Gram-negative bacteria, mycobacteria, anaerobic bacteria, fungi and viruses. The MALDI-TOF is an easy to use, rapid, reliable, economical, and environmentally friendly methodology. However, this technology needs further development of research protocols that will be validated for routine application.