Application of matrix-assisted laser desorption/ionization-time of flight mass spectrometry for the ;identification of Helicobacter pylori / 中华检验医学杂志

ABSTRACT

Objective To optimize the pre-treatment method before detecting Helicobacter pylori ( H.pylori ) by matrix-assisted laser desorption ionization/time-of-flight mass spectrometry ( MALDI-TOF MS) and evaluate the ability of the Superspectra by MALDI-TOF MS for identifying clinical isolated H.pylori strains.Methods H.pylori were isolated from 469 biopsy samples of gastric mucosa collected from January 2015 to July 2016 in Huadong Hospital affiliated to Fudan University , 16 s rRNA sequencing were then performed to validate the strains.Then 91 isolated H.pylori strains were used for the subsequent MALDI-TOF analysis.The effect of pre-treatment of 50%isopropanol, formic acid and acetonitrile (1∶1), 70%formic acid were compared before H.pylori detecting by MALDI-TOF MS.40 out of 91 clinical H.pylori strains were detected by MALDI-TOF MS and the spectra were randomly assigned to 4 groups including 5, 10, 20, 30 spectra, each group had 3 repeats.Then 4 groups with different amount of spectra were used for creating Superspectra with SARAMIS Premium software , respectively.The remaining 51 H.pylori strains including 306 spectra were used for validating the identification rate of the Superspectra.Results With the use of 70%formic acid, the greater number of ion signals and higher relative intensity of the main peaks were observed than other pre-treatment reagents.The identification rate of Superspectra created by 30 strains group was the highest ( 90.2%).Among the 306 spectra, 46.1% of them achieved highly reliable identification , 22.2% achieved lower degree of reliable identification , and 31.7% of them achieved “no identification”.Conclusions The study optimized the pre-treatment method before H.pylori detecting by MALDI-TOF MS.The Superspectra was created with the good ability to rapidly identify clinical isolated H.pylori strains.