Identification of Elizabethkingia species by MALDI-TOF MS proteotyping

ABSTRACT Elizabethkingia species, isolated from clinical and environmental samples, are emerging opportunistic bacterial pathogens with a high mortality rate in clinical settings worldwide. Taxonomically, Elizabethkingia comprises seven species: E. anophelis , E. argenteiflava , E. bruuniana , E. meningoseptica , E. miricola , E. ursingii , and E. occulta . In this study, we identified useful biomarker proteins, including ribosomal L29, L30, S21, and the YtxH domain-containing proteins, for distinguishing Elizabethkingia species using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) profiles. Evaluation of 29 clinical and environmental Elizabethkingia strains revealed that these species could be separated by MALDI-TOF MS profiles into six groups —E. anophelis , E. argenteiflava , E. bruuniana/E. miricola , E. meningoseptica , E. ursingii , and E. occulta —based on the four biomarker protein peaks. This study demonstrates the potential of routine MALDI-TOF MS -based examination methods for the early detection of Elizabethkingia species in clinical laboratories. IMPORTANCE Elizabethkingia species are groups of emerging opportunistic bacterial pathogens with a high mortality rate, causing healthcare-associated outbreaks worldwide. Rapid identification of Elizabethkingia species is important becausethese species show intrinsically carbapenem resistance and there are few data for using appropriate antibiotics. Until now, only whole-genome sequencing could accurately identify the seven Elizabethkingia species. Therefore, establishing rapid and accurate identification methods for Elizabethkingia species in clinical laboratories is vital. In this study, we developed new methods for identifying Elizabethkingia species using four biomarker protein peaks-ribosomal L29, L30, S21, and the YtxH domain-containing proteins by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) proteotyping. This study demonstrates the potential of routine MALDI-TOF MS -based laboratory examination for the early identification of Elizabethkingia species.