Evaluation of laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) for identification of anaerobe bacteria

Evaluation of Laser Desorption/Ionization Time of Flight Mass Spectrometry (MALDI-TOF MS) for Identification of Anaerobe Bacteria INTRODUCTION AND AIM: The aim of this study to investigate the identification of anaerobic bacteria from colonies and directly blood culture bottles by using MALDI-TOF MS method by comparing with conventional and automated commercial methods. MATERIAL AND METHOD: 67 clinical isolates and 2 standard strains were examined in the study. Identification by conventional methods, Vitek 2 identification system, from grown colonies and directly blood culture bottles by MALDI-TOF MS was tested. With the MALDI-TOF MS method, bacteria were identified directly from the blood culture bottles with the method optimized by us. In this method, the sample taken from the supernatant part obtained after a few centrifugation and extraction processes was read in MALDI-TOF MS device. RESULTS: From a total of 69 anaerobic bacteria; with conventional methods, 6 (%8,7) of them at the species level and 49 (%71) of them at the genus level; with the Vitek 2 system, 36 (%52,1) of them at the species level and 54 (78.2%) of them at the genus level; with MALDI-TOF MS from the bacterial colonies, all of them (%100) at the species level; with MALDI-TOF MS from the direct blood culture bottles, 43 (%62,3) of them at the species level and 47 (68.1%) of them at the genus level were correctly identified. CONCLUSION: In this study, it was determined that MALDI-TOF MS method can be used with great success for identifying anaerobic bacteria from both colonies and directly blood culture bottles and significantly shorten the result time. The results obtained are broadly consistent with conventional and automated commercial methods, with a higher proportion of gram-negative anaerobic bacteria. However, the method has not yet been standardized to be used in all laboratories. More detailed and comprehensive studies are needed on this subject.