Abstract:

Objective To evaluate the role of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry（MALDI-TOF MS） combined with sodium dodecyl sulfate（SDS） and saponin（SAP） pretreatment for rapid identification of positive blood culture. Methods A total of 296 positive blood cultures were collected in Xinhua Hospital,Shanghai Jiao Tong University School of Medicine from April 2018 to April 2019. The positive blood cultures were pretreated with SDS and SAP,and the pellets of bacteria were acquired and determined by MALDI-TOF MS. The traditional identification of inoculated culture from positive blood cultures were regarded as golden standard. The identification accuracies of the 2 methods were compared and analyzed. Results The identification accuracies of 272 positive monomicrobial blood cultures using MALDI-TOF MS combined with SDS and SAP pretreatment were 77.2% and 70.6% for species level,respectively（P=0.079）. The identification accuracies were 83.1% and 75.7% for genus level,respectively（P=0.034）. The identification accuracies of 24 positive polymicrobial blood cultures using MALDI-TOF MS combined with SDS and SAP pretreatment were 62.5% and 58.3% for 1 species of bacteria which was identified to species level,respectively（P=0.551）. Conclusions The high identification accuracy of MALDI-TOF MS combined with SDS and SAP pretreatment can help us with reporting the bacterium species that cause bloodstream infection to clinicians rapidly and accurately and provide a reference for clinical empirical anti-infection treatment. SDS is slightly better than SAP as a cell lysis agent.

Key words: Sodium dodecyl sulfate, Saponin, Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, Blood culture, Pathogen, Rapid identification