Rapid identification of microorganisms is critical in hospitalized infected patients. Blood culture is currently the gold standard for detecting and identifying microorganisms causing bacteremia or sepsis. The introduction of mass spectrometry by matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF MS) in microbiology laboratories, especially in microorganisms growing in blood culture bottles, provides rapid identification. This study evaluates the performance of the Maldi Sepsityper Biotyper procedure (hereinafter, MS) compared to that of an in-home method (hereinafter, HF). Eight hundred and forty (840) positive blood culture bottles were processed using the HF procedure, 542 of which were also processed using MS. The organisms were identified in 670 (79.76%) and 391 (72.14%) bottles respectively (p = 0,0013). This study demonstrates the effectiveness of both procedures for identifying microorganisms directly from positive blood culture bottles. However, the HF procedure proved to be more effective than MS, especially in the presence of Gram positive organisms.

Objectives: In this study, we evaluated a rapid and simple protocol for direct identification of microorganisms with Matrix-Assisted Laser Desorption/Ionization Time of Flight, Mass Spectrometry (MALDI-TOF MS) after a short incubation in solid medium (3 to 5h). Methods: We have examined a total of 1101 positive blood culture bottles from 782 patients. Results: We obtained a correct identification in 1037 (94.18%); 190 (98.44%) were Staphylococcus aureus, and 386 (98.44%) Enterobacteriaceae. Both are the most frequent etiological agents of sepsis. A total of 1004 bottles were monomicrobial (96.81%) and 33 (3.18%), polimicrobial. In the latter we identified at least one species. Two hundred eighty (27.00%) organism isolated were considered skin contaminant. Carbapenemase tests were performed with Blue-Carba test in 140 patinas from Gram negative bacilli, we have detected earlier 27 of 29 positive (93.10%). Conclusions: Mass spectrometry by MALDI-TOF MS is very useful to quickly identify the microbial agent and Blue-Carba contribute to adapt the antibiotic therapy to obtain a correct clinical management of the patient with bacteremia.