Development of O Antigen Rapid Typing by MALDI-TOF MS

Abstract

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), which provides high sensitivity and high resolution, has been used for the analysis of biopolymers. In the past decade, MALDI-TOF MS has been utilized in clinical fields around the world to identify microbial species. However, serotype or strain discrimination of the same bacterial species is difficult by MALDI-TOF MS. Different methods such as PCR and immunoassay are performed for the serotype identification. However, these assays required previous preparation and selection of each probe for every candidate, which is extremely complicated. This study developed a method to measure different O antigens from a single colony of E. coli by MALDI-TOF MS within one hour. From mixtures of E. coli strains with different O antigens, each colony can be assigned without column or HILIC manipulation. This O antigen (serotype) identification method, combined with the conventional MALDI biotyping (species) method toward ribosomal protein, would be a powerful technique for microorganism identification.