title: Rapid identification of bacterial and fungal pathogens from positive blood cultures by MALDI-TOF MS.
abstract: Sepsis is a syndrome characterized by a systemic inflammatory response due to severe infection. Early detection of causal agents and appropriate antimicrobial treatment reduce mortality. Conventional microbiological methods often do not provide time critical results for an optimal early management. We used an in-house protocol based on Tween 80 to process 109 positive blood cultures for bacteria and yeast identification by matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry (MALDI-TOF MS), and results were compared to standard reference or automated methods. MALDI-TOF MS correctly identified 91.7% of the isolates. Correct identification was obtained for 57/62 (91.9%) aerobic/facultative anaerobic Gram-positive isolates, 53 (85.5%) at species level, and 4 (6.4%) at the genus level; 32/32 (100%) aerobic/facultative anaerobic Gram-negative isolates, 31 (96.9%) at species level, and 1 (3.1%) at the genus level; 7/7 (100%) obligate anaerobes, all at the genus level; 3/7 (42.8%) fungi, all at genus level. Overall, the median identification time of MALDI-TOF MS vs reference standard methods was significantly shorter: median (interquartile range) 7.1h (4.7-10.2) vs 48.1h (32.5-50.0), p<0.0001. MALDI-TOF MS is a valuable tool for rapid identification of pathogens in septic patients. An in-house protocol based on Tween 80 can be used to process positive blood cultures.
authors.affiliation: Microbiology Section, Department of Experimental Medicine and Biochemical Sciences, University of Perugia, Perugia, Italy.
authors.forename: Christian
authors.initials: C
authors.lastname: Leli
authors.forename: Elio
authors.initials: E
authors.lastname: Cenci
authors.forename: Angela
authors.initials: A
authors.lastname: Cardaccia
authors.forename: Amedeo
authors.initials: A
authors.lastname: Moretti
authors.forename: Francesco
authors.initials: F
authors.lastname: D'Alò
authors.forename: Rita
authors.initials: R
authors.lastname: Pagliochini
authors.forename: Mariella
authors.initials: M
authors.lastname: Barcaccia
authors.forename: Senia
authors.initials: S
authors.lastname: Farinelli
authors.forename: Simona
authors.initials: S
authors.lastname: Vento
authors.forename: Francesco
authors.initials: F
authors.lastname: Bistoni
authors.forename: Antonella
authors.initials: A
authors.lastname: Mencacci
mesh_terms: D001419:Bacteria / Q000737:chemistry / Q000145:classification / Q000302:isolation & purification*; D001769:Blood / Q000382:microbiology*; D005658:Fungi / Q000737:chemistry / Q000145:classification / Q000302:isolation & purification*; D006801:Humans; D008828:Microbiological Techniques / Q000379:methods*; D018805:Sepsis / Q000175:diagnosis* / Q000382:microbiology; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013997:Time Factors