Direct antimicrobial susceptibility testing from the blood culture pellet obtained for MALDI-TOF identification of Enterobacterales and Pseudomonas aeruginosa

Direct Rapid Identification from Positive Blood Cultures by MALDI-TOF MS: Specific Focus on Turnaround Times

“…In other studies, using different lysis methods (Saponin, NH 4 Cl, KHCO 3 , and Triton X-100), the rates of species identification varied from 90% to 94% in Gram-negative and 73% to 85% in Gram-positive bacteria and were lower than our study ( 19 , 23 , 27 – 29 ). Concordant with our data, two studies reported rates of 100% correct identification at the species level in Gram-negative bacteria with 5% sodium dodecyl sulfate ( 25 ) and hemolysis buffer containing NH 4 Cl, NaHCO 3 , and EDTA ( 20 ). In previous studies using serum separator tubes, rates of correct identification of Gram-negative bacteria varies from 93% to 100% and identification of Gram-positive varies from 83% to 92% ( 17 , 21 , 30 ).…”

An improved protocol for bacteria identification by MALDI-TOF MS directly from positive blood cultures

“…In Barnini et al, where only an extraction protocol was used in Gram-positive bacteria, the rate of unidentified isolates was reported to be 6% [ 13 ]. In a study with a protocol used only to ID Enterobacterales and Pseudomonas aeruginosa, all the isolates were identified from the pellet [ 10 ]. The FAST-PBC Prep TM cartridge (Qvella) is an automated system with an extraction protocol for both gram-positive and gram-negative bacteria and showed correct ID in 94% or 90% of samples, respectively.…”

Impact of Automated Blood Culture Systems on the Management of Bloodstream Infections: Results from a Crossover Diagnostic Clinical Trial

“…All processes were performed by trained technicians using both systems, according to the same workflow after a BC bottle was flagged as positive: (i) Gram stain and subculture on blood agar and chocolate agar, (ii) identification directly from the pellet by MALDI-TOF mass spectrometry (Bruker, Germany) ( 25 ), (iii) rapid disc diffusion antibiogram, and (iv) final AST by a semiautomated microdilution system (MicroScan WalkAway; Beckman Coulter, USA). Gram stain, MALDI-TOF mass spectrometry, and AST results were communicated to the attending physician immediately if the microorganism was not considered to be a contaminant and if this was the first bacteremia episode for that patient.…”