Use of mass spectrometry for rapid diagnosis of positive blood cultures. Validation of a local algorythm

Mass spectrometry (MS) is used in identification of positive blood culture, a contribution in the clinical management of septic patients. The protocol is labor intensive and disrupts the normal workflow in a clinical laboratory. We intended to make rapid diagnosis by using MS directly from shortly incubated blood agar plates (4 to 6 hours) comparing with results of the conventional method (MC). We worked in parallel 145 positive blood cultures, with correct identification by short method in 79% of cases. We observed better yield with non carbon bottles and with gramnegative rods. With this information we designed a rapid identification algorithm using MS, which allows advancing diagnosis in 12-16 hours, without increasing to the costs or work load, since extraction protocol is not used.