MALDI-TOF mass spectrometry provides faster and more cost-effective identification of microorganisms than conventional methods. It can identify bacteria from clinical samples in just 6 minutes with over 90% accuracy. This is much faster than traditional techniques which can take 5-48 hours. MALDI-TOF is also cheaper, costing at least a quarter of conventional automated identification systems. It has been shown to reliably identify many medically relevant bacteria down to the species level as well as directly from clinical samples without culturing. This technology has the potential to improve antimicrobial stewardship through more efficient treatment optimization.

1. Improved Medical Education in Basic
Sciences
for Better Medical Practicing
ImproveMEd
The MALDI-TOF application in diagnostic of microbial agents of contagious
diseases
Domagoj Drenjancevic

2. Identification of microorganism
• detection of phenotypic characteristics
• Gram stain, colony
• morphology, microscopic examination, differential growth onselective media
and various biochemical tests
• manual or automated methods
• Molecular diagnostic methods
• 16S ribosomal RNA sequencing
• real-time PCR detection of selected genes
• complicated and costly
• MALDI-TOF MS
Bizzini A, Greub G. Clin Microbiol Infect 2010; 16: 1614–1619

3. MALDI-TOF MS: Matrix-assisted laser desorption
ionization time-of-flight mass spectrometry -
Advantages
• Implementation in a clinical microbiology laboratory - ease of use
• Performance of MALDI-TOF MS-based bacterial identification with routine
samples:
• >90% - efficient
• Reliable method for the identification of bacteria from clinical samples
• Cost-effectiveness:
• at least ¼ of the price of conventional methods
• (€2.44 with MALDITOF MS vs. €4.60–13.85 with an automated identification
• System Speed
• of 6 min, whereas
• conventional techniques - same identifications in 5–48 h
• Antimicrobial stewardship:
• can be used, together with local antibiotic resistance data
• efficiently optimize early empirical antibiotic treatment

4. Workflow fo MALDI-TOF MS

5. Clark A E et al. Clin. Microbiol. Rev. 2013;26:547-603

6. Principle of MALDI-TOF
Molecular masses
Time of Flight

7. The power of MALDI TOF MS: specific species
studies
• theoretically no limit to the identification ability: gave nearly 100% correct
identifications
• Neisseria
• Clostridia
• Mycobacteria
• Nonfermenters
• Salmonella
• viridans streptococci
• Helicobacter pylori
• Yeasts (96% of 250 clinical Candida isolate)
• filamentous fungi and dermatophytes - Further improvements in databases and pre-
analytical protocols needed

8. The power of MALDI TOF MS: Direct
identification of pathogens in samples
• direct identification of pathogens in the sample itself, without a
culture step
66-90 % of correct identification

9. The power of MALDI TOF MS: antibiotic
susceptibility testing – in progress
• ability of mass spectrometry to distinguish methicillin-susceptible S.
aureus from methicillin-resistant S. aureus
• various bacterial targeting antimicrobial molecules (such as b-
lactamases, methylases and efflux pumps) might possibly be detected
• detection of Panton–Valentine leukocidin sensitivity of 100% and
specificity of 90.6%

10. MALDI-RE (SEQUENOM) and electrospray
ionization mass spectrometry (ESI-MS)
• alternative technologies for typing
• analyse amplification products of PCR
Emonet S at al. Clin Microbiol Infect 2010; 16: 1604–1613

11. MALDI – TOF Laboratory Integration
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12. Conclusions
• speed, ease of use and low per-sample cost
• revolution in clinical microbial diagnostics