Accurate and rapid identification of bacteria is critical for the appropriate management of infections. Bacterial identification relies primarily on culture-based methodologies that requiring 24 hours for isolation and an additional 24 to 48 hours for species identification. Recently, Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) has been introduced in diagnostic microbiology laboratories as rapid, highly accurate and cost-effective method for routine identification of a wide range of microorganisms. To evaluate the analytical and practical performance of MALDI-TOF MS (VITEK MS) system in comparison to conventionalVitek2 system for identification of Gram-negative bacilli. A total of100 aerobic Gram-negative bacilli isolates representing 10 genera and 14 species obtained from different hospital wards were analyzed. Unmatched results were further investigated by16s rRNA gene sequencing as a reference method. 88 isolates (88%) had completely matched results by both systems, while12 isolates had unmatched results. VITEK MS identified all of isolates (100%) to the genus level and 98% of isolates to the species level, while Vitek2 identified 97%, and 90% to genus and species level respectively. VITEK MS also reduces the time and cost for routine identification of the studied isolates. Our result showed that VITEK MS is accurate, convenient, simple, rapid and cost saving technique for routine bacterial identification and it has a potential to replace the biochemical and other phenotypic systems for routine identification of Gram-negative bacteria in the clinical microbiology laboratory.

Download this article as