Comparative Assessment of Matrix Assisted Laser Desorption Ionization Time of Flight Mass Spectrometry and Conventional Methods in the Identification of Clinically Important <i>Enterococcus</i> Species
DOI:
https://doi.org/10.65129/health.v1i3.93Keywords:
Antimicrobial Resistance, Enterococcus, High Level Gentamicin, Mass Spectrometry, Minimum Inhibitory, Vancomycin Resistant EnterococciAbstract
Introduction: Enterococcus species, part of the normal gut flora, have emerged as significant nosocomial pathogens causing urinary tract infections, bacteremia, endocarditis, wound infections, and intra-abdominal infections. The rise of Vancomycin-resistant Enterococci (VRE), with a global prevalence of approximately 12.4%, poses a major therapeutic challenge. This study compared conventional identification methods with MALDI-TOF MS and evaluated antimicrobial susceptibility patterns. Methods: A cross-sectional study was conducted at PSG IMS & R from January to June 2025. A total of 200 Enterococcus isolates from blood, urine, and pus samples were identified using conventional biochemical tests (Gram stain, catalase, bile esculin, PYR, growth at pH 9.6, 6.5% NaCl tolerance, and carbohydrate fermentation) and MALDI-TOF MS. Antimicrobial susceptibility testing was performed using the VITEK 2 system, and MIC values were interpreted accordingly. Results: Conventional methods identified 97 Enterococcus faecalis and 94 Enterococcus faecium isolates but could not reliably identify other species. MALDI-TOF MS identified 97 E. faecalis, 94 E. faecium, 4 E. gallinarum, 2 E. casseliflavus, 2 E. raffinosus, and 1 E. avium. E. faecium demonstrated lower susceptibility to ampicillin (50%), ciprofloxacin (40%), high-level gentamicin (25%), and vancomycin (75%), but high susceptibility to linezolid (98%). E. faecalis showed higher susceptibility to vancomycin (99%), linezolid (99%), ampicillin (80%), and penicillin (79%), with lower susceptibility to ciprofloxacin (35%) and erythromycin (30%). Conclusion: MALDI-TOF MS demonstrated superior species-level identification compared to conventional methods and is a rapid, cost-effective tool for routine laboratory diagnosis. Higher rates of vancomycin and high-level gentamicin resistance were observed in E. faecium compared to E. faecalis, highlighting the need for continuous antimicrobial surveillance.
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