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

Background: Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) is a powerful tool that has initiated a revolution in the clinical microbiology laboratory for identification of nosocomial pathogens. The efficacy of MALDI-TOF MS produced by bioMerieux, Marcy l'Etoile, France (VITEK MS) for detecting Corynebacterium remains unknown. Methods: Corynebacterium isolates were isolated from clinical specimen in a tertial teaching hospital from 2012 to 2013. All strains confirmed by rpoB sequencing were identified by API Coryne (bioMerieux), Phoenix (BD) and VITEK MS, respectively. The coincidence rate was used to evaluate the consistency and accuracy across three methods. Results: In all, 75 Corynebacterium isolates were collected in this study. The dominant isolates were Corynebacterium striatum (58.7%), Corynebacterium jeikeium (16.0%), Corynebacterium amycolatum (5.3%), Corynebacterium urealyticum (5.3%), Corynebacterium glucuronolyticum (2.7%) and Corynebacterium minutissimum (2.7%). We found that there was no significant difference in the identification of corynebacterium to genus level by MS (100%, 75/75) or Phoenix (93.3%, 70/75) (P=0.058). However, 92.0% (69/75) strains were successfully identified to species by MS while which by Phoenix and API was 78.7% and 65.3% respectively. Compared with gene sequencing, the coincidence rate of identification by MS was significantly higher than Phoenix (P=0.036) and API (P<0.001). Compared with API Coryne (bioMerieux) and Phoenix, VITEK MS shown significant shorter detecting period and less cost. Conclusions: VITEK MS was a powerful tool, which could be applied in clinical laboratory, improving the diagnosis for Corynebacterium infection.