Rapid identification of Brucella by MALDI-TOF MS / 国际检验医学杂志

ABSTRACT

Objective To establish Brucella peptide mass fingerprint database by MicroflexTMLT MALDI-TOF mass spectrometer ,and evaluate its application value in the identification of clinical isolates of Brucella. Methods In October 2013 ,a suspected Brucella strain was isolated in the microbiology laboratory of the hos-pital.It was confirmed as Brucella meltensis by VITEK ? 2 Compact automatic microbial analysis system and 16S rDNA gene sequencing.Brucella peptide mass fingerprint database was established with this strain ac-cording to the manufacturer's recommended method.Two suspected Brucella strains isolated in the laboratory in April 2015 and June 2016 were tested for Gram stain ,Kozlowski stain and biochemical reactions such as oxi-dase ,catalase and rapid urease activity.MicroflexTM LT mass spectrometer was used to collect the mass spec-trums of these two strains and three suspected Brucella strains isolated from other hospitals.When these spectrums were comparatively analyzed ,self-built database was added on the basis of the MALDI Biotyper da-tabase.The 16S rDNA gene sequencing was also used to identify the above-mentioned bacteria.Results Ac-cording to the recommended self-built database construction process ,Brucella peptide mass fingerprint data-base based on BRUxh1 was obtained successfully.The suspected Brucella strains isolated in April 2015 and June 2016 showed small Gram-negative coccobacillus under microscopic examination of stained smear ,and were positive for oxidase ,catalase ,urease activity (within 5 min).The identification results of mass spectrom- etry for the 5 suspected strains were all Brucella (mass spectrometry score2.407 ,2.475 ,2.436 ,2.466 and 2.397).The 5 strains were confirmed as Brucella by 16S rDNA gene sequencing.Two strains among bacteria from other hospitals were falsely identified as Roseomonas gilardii by the VITEK?2 Compact system.Conclu-sion The combination of MALDI Biotyper database and self-built Brucella database can be used to compara-tively analyze the mass spectrometry of clinical isolates.Accurate identification of Brucella can be achieved by this means.The method which is fast and sensitive has high application value for rapid clinical diagnosis of Brucellosis.