title: Same day identification and full panel antimicrobial susceptibility testing of bacteria from positive blood culture bottles made possible by a combined lysis-filtration method with MALDI-TOF VITEK mass spectrometry and the VITEK2 system.
abstract: Rapid identification and antimicrobial susceptibility testing of microorganisms causing bloodstream infections or sepsis have the potential to improve patient care. This proof-of-principle study evaluates the Lysis-Filtration Method for identification as well as antimicrobial susceptibility testing of bacteria directly from positive blood culture bottles in a clinical setting. A total of 100 non-duplicated positive blood cultures were tested and 1012 microorganism-antimicrobial combinations were assessed. An aliquot of non-charcoal blood culture broth was incubated with lysis buffer briefly before being filtered and washed. Microorganisms recovered from the filter membrane were first identified by using Matrix-Assisted Laser Desorption/Ionization Time-of-Flight VITEK® Mass Spectrometry (VITEK MS). After quick identification from VITEK MS, filtered microorganisms were inoculated to VITEK®2 system for full panel antimicrobial susceptibility testing analysis. Of 100 bottles tested, the VITEK MS resulted in 94.0% correct organism identification to the species level. Compared to the conventional antimicrobial susceptibility testing methods, direct antimicrobial susceptibility testing from VITEK®2 resulted in 93.5% (946/1012) category agreement of antimicrobials tested, with 3.6% (36/1012) minor error, 1.7% (7/1012) major error, and 1.3% (13/1012) very major error of antimicrobials. The average time to identification and antimicrobial susceptibility testing was 11.4 hours by using the Lysis-Filtration method for both VITEK MS and VITEK®2 compared to 56.3 hours by using conventional methods (p<0.00001). Thus, the same-day results of microorganism identification and antimicrobial susceptibility testing directly from positive blood culture can be achieved and can be used for appropriate antibiotic therapy and antibiotic stewardship.
authors.affiliation: Department of Pathology and laboratory Medicine, Emory University School of Medicine, Atlanta, Georgia, United States of America.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Machen
authors.affiliation: Department of Pathology and Laboratory Medicine, Grady Health System, Atlanta, Georgia, United States of America.
authors.forename: Tim
authors.initials: T
authors.lastname: Drake
authors.affiliation: Department of Pathology and laboratory Medicine, Emory University School of Medicine, Atlanta, Georgia, United States of America ; Department of Pathology and Laboratory Medicine, Grady Health System, Atlanta, Georgia, United States of America.
authors.forename: Yun F Wayne
authors.initials: YF
authors.lastname: Wang
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects / Q000302:isolation & purification*; D001431:Bacteriological Techniques; D001433:Bacteriolysis / Q000187:drug effects*; D005374:Filtration / Q000379:methods*; D008826:Microbial Sensitivity Tests / Q000379:methods*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013997:Time Factors
chemical_list: D000900:Anti-Bacterial Agents