Application of MALDI-TOF MS as a Diagnostic Tool for Pathogenic Bacteria in Clinical Microbiology

The rapid and accurate identification of pathogenic bacteria is critical for effective diagnosis and treatment in clinical microbiology. While conventional methods are time-consuming, Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) has emerged as a revolutionary tool for microbial identification. This study aimed to evaluate the application of MALDI-TOF MS for the diagnosis of pathogenic bacteria isolated from clinical samples. A total of 150 clinical specimens (59 blood, 46 urines, 45 stool) were collected from hospital patients. Bacterial isolates were purified and characterized using standard morphological and microscopic techniques. Identification was performed using MALDI-TOF MS, and the results were interpreted based on established score values providing confidence levels for genus and species identification. Results: Nine pathogenic bacterial species were successfully isolated and identified. MALDI-TOF MS provided rapid and reliable identification, with six out of nine isolates (Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis, and Bacillus cereus) yielding high-confidence identification scores ranging from 0.82 to 0.91. Three isolates (Salmonella typhi, Staphylococcus haemolyticus, and Enterobacter aerogenes) were identified at the genus level with lower confidence in species assignment (scores 0.73-0.79), highlighting the technique's limitations with closely related species. Conclusion: MALDI-TOF MS proved to be a highly effective, rapid, and robust diagnostic tool for the identification of most common bacterial pathogens in a clinical setting. Its implementation can significantly streamline laboratory workflows. However, borderline identification scores for some species underscore the importance of complementing this technology with supplementary methods for definitive confirmation, ensuring optimal patient management and antimicrobial stewardship.