PERFORMANCE OF THE VITEK MS MATRIX-ASSISTED LASER DESORPTION IONIZATION-TIME OF FLIGHT MASS SPECTROMETRY SYSTEM FOR RAPID IDENTIFICATION OF CLINICAL MICROBIOLOGY ISOLATES

Abstract

Background: Rapid and precise microbial identification is essential for timely patient management and control of infection. Conventional microbiological procedures are time-consuming, laborious, and require expertise. Recent coalition of MALDI-TOF in the microbiology workflow has yielded excellent results so far. Here we have assessed this quick proteomic based technique for clinical bacterial isolates identification. Material and Methods: All fresh bacterial isolates were selected for VITEK MS (bioMérieux, France) analysis, the bacteria were identified by using MALDI-TOF System (IVD 3.2) software. For same isolates, API (bioMérieux, France) was set as per kit instructions and conventional/biochemical tests were performed according to ASM Guidelines. Results: Among 200 isolates 99% were accurately identified by the VITEK MS system to the species level, one of two isolates was mis-identified (Shigella as E. coli) while the other was identified later by re-spotting. On testing these samples in parallel by APIs, 91.50% were correctly identified, while 8.50% (17 samples) showed discrepant results. These were re-analyzed by VITEK-2 (bioMérieux, France) semi-automated system which showed the same results as those of VITEK MS. Our findings revealed diagnostic accuracy of VITEK MS in comparison with APIs in terms of time, cost and patient management. Conclusion: For bacterial identification MALDI-TOF MS is an expeditious, authentic and comparatively inexpensive system. Our results emphasize that it is speedy technique which can replace the traditional identification methods for most of bacterial strains on their routine isolation. This ingenious approach complies with advanced patient management and therapeutic intervention. Key Words: MALDI-TOF MS, bacterial identification, VITEK-2, Analytical profile index (API), Clinical microbial isolates