Clinical application of matrix-assisted laser desorption/ionization-time of flight mass spectrometry for the identification of Shigella sonnei

BAO Chun-mei; SONG Xin-ai; CUI En-bo; WANG Huan; ZHANG Ju-ling; CHEN Su-ming; ZHANG Cheng-long; JIA Tian-ye; QU Fen; MAO Yuan-li

Abstract：objective To construct a database of Shigella sonnei isolates identified by matrix-assisted laser desorption/ioniza-tion-time of flight (MALDI-TOF-MS) in order to achieve rapid identification of clinically isolated Shigella sonnei. Methods A mass spectrometry database of Shigella sonnei isolates identified following extraction method was constructed. A total of 200 wild-type Shigella sonnei strains were identified following direct-smear method and extraction method, respectively. Meanwhile, the iden-tification by MALDI-TOF-MS was conducted for different phases of Shigella sonnei strains, at different laser intensity of the instru-ment and at different sample storage time. Then, 100 Escherichia Coli strains were identified to verify the specificity of the newly-constructed database. Results Concordance rates were 100% for the identification following extraction method, and 71.5% for the identification following direct-smear method. The results of the identification for different phases of Shigella sonnei strains and at dif-ferent laser intensity of the instrument were not significantly different (P>0.05) , and the results of the identification at different sam-ple storage time were significantly different (P<0.05). Identification concordance rate of Escherichia Coli were 96.0% based on the newly-constructed database. Conclusions Based on the database of Shigella sonnei isolates identified by MALDI-TOF-MS follow-ing extraction method, a rapid and correct identification of Shigella sonnei to the species level is obtained, and a rapid diagnosis of the clinical strains of the diarrheal pathogenic bacteria is realized.