Matrix-assisted laser desorption ionization time-of-flight mass spectrometry: a powerful tool for identification of Corynebacterium species

Corynebacterium spp. commonly colonizes the skin and mucous membranes of humans, which rarely account for clinical infections. However, several recent studies reported that Corynebacterium spp. would result in opportunistic infection including artificial joint infections, endocarditis, pneumonia and catheter-related bloodstream infections (CRBSI) (1,2). Correct and rapid identification of Corynebacterium spp. is a crucial to identify the real source of infection and install the appropriate treatment for the infection. Current bacterial identification methods such as API Cory (bioMerieux) and BD Phoenix Automated Microbiology System (Becton Dickinson, Sparks, MD, USA) are generally based on conventional phenotypic and biochemical methods. Most of these tests are laborious, time-consuming processes and do not always give reliable identification at the species level. Therefore, accurate and rapid identification of Corynebacterium spp. help clinicians to identify isolates of pathogens or contaminating bacteria. Recently, matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS), based on the protein composition of microbial cells, has emerged as a promising technique which is a rapid, reliable diagnostic tool for the identification of most microorganism including Corynebacterium spp. (3-5). There is limited data evaluating the use of this tool for the identification of Corynebacterium spp., and these studies have been done mostly using the Bruker system rather than VITEK MS (bioMérieux). The aims of our study were to evaluate the VITEK MS in quickly identification of Corynebacterium spp. by compared with API Coryne and Phoenix. All strains were confirmed by rpoB sequencing as the gold standard