Direct bacterial identification in positive blood cultures by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry using an in-house centrifugation method

Abstract

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF) can identify bacteria from positive blood cultures. Commercial sample preparation kits are available. However, such commercial kits are very expensive, making it difficult to introduce them into routine clinical microbiology laboratories. We compared the in-house preparation method and a commercial kit (Sepsityper kit). In total, 100 monomicrobial cultures were prepared in this study. The total identification rate was 67% by the in-house method and 66% using the Sepsityper kit. The identification rates of gram-positive cocci were 40% by the in-house method and 45% using the Sepsityper kit. The identification rates of gram-negative rods were 92% by the in-house method and 87% using the Sepsityper kit. The processing time of our in-house method was the same as that of the Sepsityper method. Our new method does not use a special reagent and the cost is low. We demonstrated that our in-house method is superior to the Sepsityper kit.