Application of the MALDI-TOF Mass Spectrometry Method in the Determination of the Causative Agent of Endophthalmitis. Clinical Case

Abstract

Infectious endophthalmitis (EF) is a serious problem in modern ophthalmology, which can lead to irreversible consequences for the patient’s visual functions. Timely diagnosis and timely treatment are the “key” to the successful resolution of the process. Matrix-assisted laser desorption/ionization method using matrix laser desorption/ionization. Time-of-flight mass spectrometry, or MALDI-TOF MS, aimed at determining the mass of the investigated “unknown” molecules by ionization, followed by separation and determination of the ratio of their mass to charge (m/z) with positive and negative signs. The method allows ionizing biological macromolecules (peptides, proteins, DNA, oligonucleotides, oligo- and lipopolysaccharides, etc.) as part of a special substance — a matrix — under the influence of a laser. The resulting ions are separated during the time-of-flight analyzer due to different velocity of movement, inversely proportional to the mass of the ion. Based on the source of the ionization source before the detector, the speed of movement and the ratio of mass to charge (m/z) for each ion are calculated: the heavier the molecule, the longer its flight duration. To identify bacteria, the spectrum of proteins is determined directly from the bacterial cell without preliminary long-term sample preparation. For each type of microorganism, a characteristic set of proteins (biomarkers) is formed, obtained on the basis of analysis of at least 50 mass spectra of this type (almost 100 % accuracy). This mechanism leads to the fact that different biological microorganisms form patterns, or spectra, which makes it possible to identify them by the type of “fingerprint”, while the research time itself is usually not several minutes. This article presents a clinical case of the use of MALDI-TOF MS in the diagnosis of endophthalmitis.