MALDI-TOF mass spectrometry: an emerging technology for microbial identification and diagnosis

Abstract

Currently microorganisms are best identified using 16S rRNA and 18S rRNA gene sequencing. However, in recent years matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has emerged as a potential tool for microbial identification and diagnosis. During the MALDI-TOF MS process, microbes are identified using either intact cells or cell extracts. The process is rapid, sensitive, and economical in terms of both labor and costs involved. The technology has been readily imbibed by microbiologists who have reported usage of MALDI-TOF MS for a number of purposes like, microbial identification and strain typing, epidemiological studies, detection of biological warfare agents, detection of water- and food-borne pathogens, detection of antibiotic resistance and detection of blood and urinary tract pathogens etc. The limitation of the technology is that identification of new isolates is possible only if the spectral database contains peptide mass fingerprints of the type strains of specific genera/species/subspecies/strains. This review provides an overview of the status and recent applications of mass spectrometry for microbial identification. It also explores the usefulness of this exciting new technology for diagnosis of diseases caused by bacteria, viruses, and fungi.

Misidentification of a Rare Species, Cryptococcus laurentii, by Commonly Used Commercial Biochemical Methods and Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry Systems: Challenges for Clinical Mycology Laboratories

“…Moreover, discrepant identification results were noted between local hospitals and the central laboratory using (12,(18)(19)(20). However, its application in China (Table 1) and other resource-poor countries has been limited by the initial high equipment cost (18). Unfortunately, the MALDI-TOF MS systems did not show a markedly better performance in this study, mainly owing to deficiencies in their mass fingerprint databases for rare yeast species (see Table S1 in the supplemental material) (12,18).…”

“…However, its application in China (Table 1) and other resource-poor countries has been limited by the initial high equipment cost (18). Unfortunately, the MALDI-TOF MS systems did not show a markedly better performance in this study, mainly owing to deficiencies in their mass fingerprint databases for rare yeast species (see Table S1 in the supplemental material) (12,18). Therefore, ITS rDNA sequencing is still necessary as a supplementary confirmatory test for these rare yeasts (12,20).…”

“…The present study further confirms these findings, as the Vitek 2 system was highly unreliable in the identification of C. laurentii. Moreover, discrepant identification results were noted between local hospitals and the central laboratory using (12,(18)(19)(20). However, its application in China (Table 1) and other resource-poor countries has been limited by the initial high equipment cost (18).…”

Molecular Diagnostic Tools for Nematodes

“…Recently, the use of analytical instrumentation for protein analysis has acquired the atention of the research and application scientiic community. MALDI-TOF mass spectrometry is a method that can be used for microorganism's identiication [41] and has been reported by Pepera et al [42] for nematodes as well with very good results. The authors discriminated up to a race level for Ditylenchus dipsaci.…”

Graphical illustration for explaining mass spectrum fingerprinting in microbial identification

“…2 Specifically, by profiling the set of species-specific ribosomal proteins, and subsequently, comparing the mass spectra data (particularly, peak positions) with those curated in a reference database, positive identification of the unknown microbe is possible if a match (of high similarity) can be obtained. In particular, identification of microbes via MALDI-TOF MS is usually effected by the biomarker approach, where phylogenetically significant biomolecules such as ribosomal proteins serve as identifiers for particular species and strains.…”