Comparison of three preparatory methods for detection of bacteremia by MALDI-TOF mass spectrometry.

We evaluated 3 preparatory methods for processing positive blood culture bottle broths prior to matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) analysis-differential centrifugation, 10% sodium dodecyl sulfate (SDS), and the Sepsityper kit. Initial evaluation used genus and species level cutoff scores of 1.700-1.999 and ≥ 2.000, respectively. Processing of an initial 79 blood bottle cultures by differential centrifugation yielded correct identifications of 51 (65%) to the genus and 34 (43%) to the species levels. One hundred and one different blood bottles were simultaneously processed with 10% SDS and Sepsityper. Both yielded genus-level identifications for 77 (76%), and the 2 yielded species-level identifications for 49 (49%) and 54 (54%) of bottles, respectively. Adjustment of the score cutoff criteria for genus (1.500-1.699) and species (≥ 1.700) improved identification percentages, particularly for species-level identifications (P < 0.05).