Elsevier

Clinical Biochemistry

Volume 44, Issue 1, January 2011, Pages 104-109
Clinical Biochemistry

Review
MALDI-TOF mass spectrometry tools for bacterial identification in clinical microbiology laboratory

https://doi.org/10.1016/j.clinbiochem.2010.06.017Get rights and content

Abstract

Since the early 1980s, mass spectrometry has emerged as a particularly powerful tool for analysis and characterization of proteins in research. Recently, bacteriologists have focused their attention on the use of mass spectrometry (MS) for bacterial identification, especially Matrix Assisted Laser Desorption Ionization Time-Of-Flight (MALDI-TOF). Moreover, recent publications have evaluated MALDI-TOF in microbiology laboratory for routine use. MALDI-TOF-MS is a rapid, precise, and cost-effective method for identification of intact bacteria, compared to conventional phenotypic techniques or molecular biology. Furthermore, it allows identification of bacteria directly from clinical samples (blood cultures for example).

The goal of this review was to update recent data concerning routine identification of microorganisms by MALDI-TOF in the clinical microbiology laboratory.

Section snippets

MALDI-TOF-MS

The intrinsic property of mass spectrometry is to detect the mass-to-charge ratio (m/z) of a bioanalyte, providing spectra within minutes. The method has been used to profile bacterial proteins from cell extracts and has recently been applied to the identification of microorganisms from different genera, different species, and from different strains of the same species. The procedure provides a unique mass spectral fingerprint of the microorganisms. This method requires that the biopolymer

Databases

The identification by MALDI-TOF is based on the following findings: (i) spectral fingerprints vary between microorganisms (Fig. 1), (ii) among the compounds detected in the spectrum, some peaks (molecular masses) are specific to genus, species, and sometime to subspecies, (iii ) spectra obtained are reproducible as long as the bacteria are grown under the same conditions.

The same species can give different mass spectra, owing to use of different growth conditions or different chemical

Intact bacteria

Early studies could identify a limited number of bacteria, often two different species. Actually, different systems (MALDI-TOF and databases) allowing identification of the main microorganisms (bacteria, yeasts, fungi) isolated from clinical samples are available. A new area has begun with the replacement, already effective in some laboratories, of conventional systems by MALDI-TOF-MS. All the following studies have been conducted with acquisition directly on whole bacteria obtained on Petri

Outlook and development

MALDI-TOF-MS will soon become a widely used technique in routine clinical laboratories for bacterial identification replacing automates and other phenotypic techniques. A great addition to its routine use for identification would be the detection of antibiotic resistance associated to the identified bacteria. Several teams have attempted to differentiate strains of methicillin-resistant Staphylococcus aureus (MRSA), which harbor the mecA, gene from methicillin-sensitive strains (MSSA) [16], [27]

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