Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry in Clinical Microbiology: What Are the Current Issues?

Abstract

Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) has revolutionized the identification of microbial species in clinical microbiology laboratories. MALDI-TOF-MS has swiftly become the new gold-standard method owing to its key advantages of simplicity and robustness. However, as with all new methods, adoption of the MALDI-TOF MS approach is still not widespread. Optimal sample preparation has not yet been achieved for several applications, and there are continuing discussions on the need for improved database quality and the inclusion of additional microbial species. New applications such as in the field of antimicrobial susceptibility testing have been proposed but not yet translated to the level of ease and reproducibility that one should expect in routine diagnostic systems. Finally, during routine identification testing, unexpected results are regularly obtained, and the best methods for transmitting these results into clinical care are still evolving. We here discuss the success of MALDI-TOF MS in clinical microbiology and highlight fields of application that are still amenable to improvement.

Proteomic characterization and discrimination of Aeromonas species recovered from meat and water samples with a spotlight on the antimicrobial resistance of Aeromonas hydrophila

“…As culture‐ and biochemical‐based identification of different microorganisms are difficult and time‐consuming, MALDI‐TOF MS was significantly used here for the early identification and discrimination of various pathogens from environmental samples by introducing a simple, rapid, precise, and low‐cost identification method compared to other methods (Elbehiry et al, ; Singhal, Kumar, Kanaujia, & Virdi, ; van Belkum, Welker, Pincus, Charrier, & Girard, ). Recently, MALDI‐TOF MS has been revealed to be an important method for the rapid identification of bacterial threats that might contaminate drinking water and food products (Singhal et al, ).…”

Microbial Proteomics and Their Importance in Medical Microbiology

“…Culture-based diagnosis of clinical samples on solid selective enrichment medium is very sensitive, easily contaminated, labor-dependent, and a timeconsuming process; there's a chance for error to occur in these diagnosis reports. Currently, some automated identification systems give reliable results in shorter periods of time and also antimicrobial susceptibility testing (van Belkum et al, 2013). Molecular methods are more accurate, specific, sensitive, and faster than traditional culture-based methods, because they use more stable genotypic characteristics than reversible phenotypic characteristics.…”

“…MALDI-TOF MS is a rapid, easy, relatively inexpensive, and high-throughput method for identifying clinically relevant bacteria and fungi. MALDI-TOF MS methods are implemented in identifying common microorganisms (Cobo, 2013;van Belkum et al, 2017). Characterization of pathogen, based on MALDI-TOF MS fingerprinting profiling, is now a routine in diagnostic microbiology; the entire process is completed in four steps, i.e., detection, ID, susceptibility testing, and epidemiology.…”

Antifungal susceptibility testing ofAspergillus nigeron silicon microwells by intensity-based reflectometric interference spectroscopy

“…8,10,11 In particular, matrix-assisted laser desorption-ionization time of flight mass spectrometry (MALDI-TOF MS) has been used for species discrimination and the identification of resistance by analyzing protein fingerprints of fungal isolates. [12][13][14] Rapid AFST by MALDI-TOF MS is achieved within 3 h by investigating proteomic changes due to exposure of fungal cells to antifungal agents. 14,15 Nonetheless, the disadvantages of mass spectrometry for AFST include high acquisition costs, the need for optimized preparation protocols and further validation, as well as the ability to detect resistance only in selected cases.…”

“…14,15 Nonetheless, the disadvantages of mass spectrometry for AFST include high acquisition costs, the need for optimized preparation protocols and further validation, as well as the ability to detect resistance only in selected cases. 6,12 Genotypic AFST consisting of nucleic acid-based strategies to identify resistance-conferring mutations 8 can be expensive 12 and limited due to the lack of identifiable resistance markers for some antifungal agents and multiple mutations and mechanisms that can confer resistance. 11,16,17 Furthermore, genomic AFST does not allow for phenotype-based determination of minimal inhibitory concentrations (MIC) and is not yet standardized for practical use in most clinical laboratories, 11 suggesting that the development of rapid, sensitive and affordable phenotypic methodologies for AFST is crucial.…”