The Value Of Vitek MS In Identifying The Clinical Bacteria

Aim:To evaluate the value of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALD1-TOF MS) in rapidly identifying the clinical bacteria. Methods:Vitek MS system (bioMerieux, Marcy I’Etoile) was compared with the other conventional methods (included Phoenix, API and other manual methods) in identifying the 960 bacteria and 59 yeasts, which were obtained from Fudan University Affiliated Zhongshan Hospital.16S rRNA or rpoB gene sequencing was performed as a reference identification method in cases of discrepant results. Results:960 bacteria contained 32 genus and 78 species,900 of which were identified by Vitek MS and automatic microbiology system. Using automatic microbiology system,745 isolates (82.8%) were correctly identified to the species level and 880 (97.8%) to the genus level. In comparison, the Vitek MS system correctly identified 848 (94.2%) isolates to the species level and 890(98.9%) to the genus level. There were significant difference between Vitek MS and automatic microbiology system in identifying the bacteria to the species level (p=0.000). The remaining 60 isolates were identified by API/other manual methods and Vitek MS. Vitek MS performed better, with a result of 56(93.9%) isoleates were correctly identified to species, while only 47(78.3%) isolates by another method(p=0.034). A total of 59 yeasts, including 56 non-Candida albicans, two Cryptococcus neoformans and one Trichosporon asahii were analyzed by Vitek MS, with 84.7% isolates were correctly identified to species level. Compared with current bacterial identification methods, which usually required significant time commitment ranging from two to twelve hours, complex manufacture and a high consumable cost, Vitek MS not only needed a few minuters but less consumable. Conclusions: compared to conventional identification methods, MALDI-TOF MS has a rapid, accurate and economical technique to enhance the clinical value of microorganism idenfication.