Impact of MALDI-TOF in the Routine Diagnostic Microbiology Laboratory in Alexandria University, Egypt

Abstract

Background: In the last few years, matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) has emerged as a useful tool for identification of microorganisms. Identification of the various bacterial genera has been found to be challenging using the routine phenotypic tests or commercially available automated systems relying on the biochemical identification of bacteria. Objectives: In this study, we aimed to evaluate the possible role of the MALDI-TOF system with its Biotyper software as an accurate and rapid method of bacterial identification. Methodology: This study was conducted over a period of one month, where 299 isolates were retrieved from 523 clinical samples. Results: MALDI TOF identified 275 (92%) isolates to the species level, 287 isolates (96%) to the genus level and no reliable identification for 12 (4%) isolates using the direct formic acid application method. When protein extraction was applied, valid results for species and genus identification were obtained for 296 and 299 isolates respectively, so the overall rate of identification rose to 99% and 100% respectively. Discordant results between MALDI TOF and conventional methods were confirmed by Vitek 2 and 16s rRNA sequencing. Conclusions: MALDI-TOF is a rapid, accurate and inexpensive method for microbial identification that rivals other identification systems available. Its relative ease of use and rapid turnaround time makes it a powerful tool in the microbiology laboratory.