Rapid identification of common clinical organism by matrix-assisted laser desorption/ionization time of-fright mass spectrometry / 中华检验医学杂志

ABSTRACT

Objective To estimate the application for the rapid identification of common clinical bacteria by MALDI-TOF MS. MethodsFour hundred and twenty-six bacteria, including Salmonella spp strains collected from Zhejiang center for disease control and prevention were collected from blood, sputum,secretion and urine in 2nd Affiliated Hospital of Zhejiang University during December 2008 to August 2009. The isolates included 76 gram positive coccus and 350 gram negative bacilli. Species identification was performed with the Vitek system, and serotypes of Salmonella and Shigella were determined by serum agglutination test. 16s rDNA gene of 91 bacteria were amplified by PCR. The RCP products were sequenced. Then the results were compared with the reported sequences from GenBank. All strains were identified by MALDI-TOF MS. Results of three identification methods were compared with each other. Results Among 426 tested isolates, identification results from Vitek system and MALDI-TOF MS for gram positive coccus and 323 out of 350 gram negative bacilli (exception for Salmonella and Shigella spp.),were identical. For 23 Salmonella and Shigella spp. , only 2 Salmonella enterica subsp, enterica serovar Typhimurium were identified the same results by the three methods. Besides, results from Vitek system and serum agglutination test for 1 Salmonella enterica subsp, enterica serovar Typhi, 3 Salmonella enterica subsp.enterica serovar Paratyphi A, 1 Salmonella enterica subsp, enterica serovar Paratyphi B, 1 Salmonella enterica subsp, enterica serovar Enteritidis, and 1 Salmonella enterica subsp, enterica serovar Bovis-morbificans were consistent with that from 16S rDNA gene sequence. Four isolates which were confirmed as S. flexneri by Vitek system and serum agglutination test were identified as Escherichia coli by both 16S rDNA gene sequence and MALDI-TOF MS. ConclusionMALDI-TOF MS could be used for rapid and accurate identification of common clinical bacteria with good repeatabihty, excepting for the Salmonella and Shigella spp.