Matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) for rapid identification of micro-organisms in the routine clinical microbiology laboratory

Abstract

The study evaluates the utility of matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) Vitek MS for identification of microorganisms in the routine clinical microbiology laboratory. From May 2013 to April 2014, microbial isolates recovered from various clinical samples were identified by Vitek MS. In case of failure to identify by Vitek MS, the isolate was identified using the Vitek 2 system (bioMerieux, France) and serotyping wherever applicable or otherwise by nucleic acid-mediated methods. All the moulds were identified by Lactophenol blue mounts, and mycobacterial isolates were identified by molecular identification systems including AccuProbe (bioMerieux, France) or GenoType Mycobacterium CM (Hain Lifescience, Germany). Out of the 12,003 isolates, the Vitek MS gave a good overall ID at the genus and or species level up to 97.7% for bacterial isolates, 92.8% for yeasts and 80% for filamentous fungi. Of the 26 mycobacteria tested, only 42.3% could be identified using the Saramis RUO (Research Use Only) database. VITEK MS could not identify 34 of the 35 yeast isolates identified as C. haemulonii by Vitek 2. Subsequently, 17 of these isolates were identified as Candida auris (not present in the Vitek MS database) by 18S rRNA sequencing. Using these strains, an in-house superspectrum of C. auris was created in the VITEK MS database. Use of MALDI-TOF MS allows a rapid identification of aerobic bacteria and yeasts in clinical practice. However, improved sample extraction protocols and database upgrades with inclusion of locally representative strains is required, especially for moulds.

Increasing Complexity to Simplify Clinical Care: High Resolution Mass Spectrometry as an Enabler of AI Guided Clinical and Therapeutic Monitoring

“…A multicenter, multicountry clinical trial showed replicability in identification of microbiological strains. [ 115 ] This resulted in the development of MALDI‐TOF MS for clinical use in diagnostic microbiology [ 110,116,125,117–124 ] and in 2013, the Bruker MALDI Biotyper CA [ 126 ] and the bioMérieux VITEK MS [ 127 ] were approved by the FDA for clinical mass spectrometry micro‐organism identification and differentiation.…”

Recent Technology of Clinical Microbiology; Whole Genome Sequencing (WGS) and Matrix-Assisted, Laser Desorption Ionization-Time of Flight Mass Spectrometry (MALDI-TOF MS)

“…Skin diphtheroids had been regarded as contaminants until MALDI-TOF enabled species identification, and reports of them acting as pathogens has increased [46]. MALDI-TOF reduces the identification time, but has limitations; it is subjective with regard to interpreting m/z peaks, is prone to technical variations, and has difficulty in identifying rare species because the database is still being updated [47,48].…”

Duplex real-time PCR assay for the simultaneous detection of Achromobacter xylosoxidans and Achromobacter spp

“…are allocated as A. xylosoxidans / A. denitrificans on this platform (18), thus providing limited capacity for accurate species-level identification. Further, VITEK ® MS and other mass spectrometry-based platforms require a purified isolate to obtain an accurate speciation result, which limits the utility of this platform as it cannot be used directly on polymicrobial clinical specimens such as sputum, resulting in longer turn-around times, potentially incorrect antimicrobial treatment, and higher costs (19, 20). In addition, mass spectrometry-based equipment has a large upfront cost and footprint, rendering this method out-of-reach for smaller, less-resourced laboratories.…”