MALDI-TOF MS for Antibiotic Susceptibility Testing
Antimicrobial resistance (AMR)-the ability of microorganisms to resist antimicrobial treatment, constitutes a global challenge that threatens the effective prevention and treatment of an ever increasing range of infections caused by bacteria and other pathogens. MALDI-TOF MS has revolutionized clinical diagnosis over the past few decades with its rapid, reliable, and economical ability to identify species and its potential to simplify antimicrobial sensitivity testing. With the complete suite of microbial solutions for live biotherapeutic product (LBP) development, Creative Biolabs can be your one-stop-shop.
What is MALDI-TOF Technology?
MALDI-TOF is a mass spectrometry method that has been successfully introduced into clinical laboratories as an identification tool. MALDI-TOF MS is an analytical technique based on the cellular proteome, which can reflect the gene products and metabolites of organisms. TOF information is used to generate characteristic mass spectrometry, called peptide mass fingerprint (PMF). This PMF has peaks for genera and species specific to individual microbial types and is then compared to a database. PMF of unknown microbial isolates is compared with those of known microbial isolates included in the database to determine the unknown microorganism in the family, genus, and species.
Fig.1 Mechanism of MALDI-TOF MS. (Yoon, 2021)
MALDI-TOF MS is a sensitive method for bacterial identification. High sensitivity and accuracy are key characteristics that make it a useful method for clinical relevance. Many studies have shown that this method is of great significance in distinguishing MRSA, MSSA, and other sensitive bacteria from drug-resistant bacteria. Conventional AST is based on bacterial growth in the presence of various antibacterial compounds. On the other hand, DNA amplification methods are faster than commonly used susceptibility tests, but they are based on the detection or deletion of specific resistance genes, which are not always associated with phenotypes. Compared to commonly used AST methods, MALDI-TOF significantly speeds up the detection of drug resistance:
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MALDI-TOF mass spectrum was performed on a given microorganism to detect the characteristic "resistance peak pattern".
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Analysis of bacterially induced hydrolysis of β-lactam antibiotics.
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Detection of stable (non-radioactive) isotope-labeled amino acids that have been incorporated into newly synthesized bacterial proteins
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Analysis of bacterial growth in the presence and absence of antibiotics using an internal standard method.
MBT-ASTRA: A Suitable Tool for Fast AST
The newly developed MALDI Biotyper antibiotic susceptibility test rapid assay (MBT-ASTRA) is a more straightforward and cost-effective modulation of MALDI-TOF MS used for both AST and MIC determination. This approach employs semi-quantitative mass spectrometry for AST. The MBT-STAR-BL assay is an already widely investigated functional assay analyzing bacterially induced hydrolysis of β-lactam antibiotics. The MBT-RESIST test is a resistance test based on the detection of amino acids labeled with stable (non-radioactive) isotopes that have been incorporated into newly synthesized bacterial proteins.
Fig.2 Overview of MALDI-TOF MS-based resistance tests currently under investigation. (Sparbier, 2016)
Advantages
The main limitation of growth-based AST is its dependence on time and labor, so the MALDI-TOF MS-based approach is thought to solve this problem. A major advantage of this technology is that it can detect antibiotics and their degradation products simultaneously, without the need for a separate test. The rapid, low-cost, and simple to conduct methodology is expanding its application in clinical microbiology laboratories to diagnose AMR in microorganisms.
LBP developers should undertake a thorough risk analysis at a very early stage in development as it may guide the design of the non-clinical and clinical programs. The risk analysis for LBPs should consider any risk intrinsic to the strain(s). As one of the largest LBP development services suppliers, Creative Biolabs has expertise and capabilities in providing high-quality AST solutions. Please contact us to get start the AST project for your LBP candidates.
References
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Yoon, E.J.; Jeong, S.H. MALDI-TOF mass spectrometry technology as a tool for the rapid diagnosis of antimicrobial resistance in Bacteria. Antibiotics. 2021, 10(8): 982.
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Sparbier, K.; et al. MBT-ASTRA: a suitable tool for fast antibiotic susceptibility testing? Methods. 2016, 104: 48-54.
For Research Use Only. Not intended for use in food manufacturing or medical procedures (diagnostics or therapeutics). Do Not Use in Humans.
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