Detection of microorganisms in blood specimens using matrix-assisted laser desorption ionization time-of-flight mass spectrometry: a review

Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) initiated a revolution in the identification of organisms grown on solid medium, including bacteria and fungi. Rapid identification of organisms responsible for septicaemia, which are typically grown in broth, is now expanding the field of application. Despite the fact that there are fewer than ten reports in the literature, published data indicate that MALDI-TOF MS yields accurate identification of blood-borne organisms in ≥80% of cases for inocula of >107 organisms/mL. A major current limitation is failure to accurately identify Streptococcus pneumoniae among viridans steptococci. Identification is achieved in <2 h, sharply reducing the turn-around time for communication of identification to the clinician. Further progress in handling protocols and automation, and extraction of antibiotic resistance data from the MALDI-TOF MS spectra, will further push this emerging approach as the standard one in the laboratory diagnosis of septicaemia, paving the way to application in further clinical situations and clinical specimens.