MALDI-TOF Mass Spectrometry in the Microbiology Lab

Identifying Antimicrobial Resistance

The Centers for Disease Control and Prevention has called antibiotic resistance public health's ticking time bomb.1 Resistant microbes, once considered outliers, are now increasingly routine. In the U.S. and Europe combined, up to 50,000 people die each year as a result of antimicrobial resistance.2,3 A reported 10 million people worldwide could die every year from this global crisis by 2050.4 Microbiology laboratories have evolved in response, finding new ways to test for resistant strains that protect patients against risk of progressing illness.

Protecting Patients Through Fast Identification

The role of the clinical microbiology laboratory is to help clinicians make timely, appropriate diagnostic and care decisions for patients with infections and infectious diseases. For this reason, speed and accuracy have long been top priorities for laboratory technicians. Over the last decade, MALDI-TOF—matrix-assisted laser desorption ionization time-of-flight—mass spectrometry has emerged as an important tool in the quest to shorten time to microorganism identification.5 Whereas traditional phenotypic and biochemical microbial identification methods may require days to complete, MALDI-TOF mass spectrometry can provide answers in minutes. This enables laboratories to contribute more effectively to antimicrobial stewardship intervention.6 It also significantly improves time to optimal therapy, while decreasing length of stay and total costs.7

Understanding MALDI-TOF Mass Spectrometry

Mass spectrometry analysis

Figure 1. Depiction of internal MALDI-TOF mass spectrometry process.

In mass spectrometry analysis, sample protein molecules are converted into ions in the gas phase and measured for their mass-to-charge (m/z) ratio. A laser strikes the target—a sample fixed to a solid surface with a matrix compound—converting the protein molecules into gas without fragmenting or decomposing them.8 

The ionized molecules are subsequently accelerated by a potential difference and fly through the field-free, high-vacuum flight tube towards the detector. The system measures the analytes’ time of flight to the detector and produces a characteristic spectrum. Lighter ions take less time to travel to the detector; heavier ions take more time.  

A software application identifies the sample by comparing the resulting pattern of mass peaks to a library of known patterns.  

The accuracy of the Bruker MALDI Biotyper as a microorganism identification system, together with its associated libraries, is considered comparable to 16S rRNA gene sequencing (the gold standard) and is globally recognized as the clinical laboratory standard for microbial identification.

DxM Trio ID/AST systems

Fast, Accurate ID/AST Testing

The DxM Trio delivers rapid mass spectrometry identification, accurate AST results and comprehensive reporting from a single platform. Find out how you can drive advanced levels of efficiency with the combination of the Bruker MALDI Biotyper, the DxM MicroScan WalkAway system and LabPro-MBT software.

Learn more
1. Centers for Disease Control and Prevention. "Detect and Protect Against Antibiotic Resistance" Fact Sheet.
2. U.S. Department of Health and Human Services Centers for Disease Control and Prevention. "Detect and Protect Against Antibiotic Resistance." Accessed 23 May 2018. 
3. World Health Organization, Europe. "Antimicrobial Resistance." Accessed 23 May 2018. 
4. O'Neill, J. "Antimicrobial Resistance: Tackling a Crisis for the Health and Wealth of Nations." The Review on Antimicrobial Resistance, 2014. Review Paper - Tackling a crisis for the health and wealth of nations_1.pdf. Accessed 23 May 2018.
5. Emonet S. et. al. “Application and Use of Various Mass Spectrometry Methods in Clinical Microbiology.” Clin Microbiol Infect. 2010, 16:1604–13.
6. Huang et. al. “Impact of Rapid Organism Identification via MALDI-TOF Combined with Antimicrobial Stewardship Team Intervention in Adult Patients with Bacteremia and Candidemia.” Clin Infect Dis, 2013, 57:1237–45.
7. Perez et. al. “Integrating Rapid Pathogen Identification and Antimicrobial Stewardship Significantly Decreases Hospital Costs.” Arch Lab Med, 2013, 137:1247–54.
8. Creative Proteomics. MALDI-TOF Mass Spectrometry. 2016. Accessed 8 May 2019. 

MALDI Biotyper is the property of Bruker Daltonik GmbH.