title: A rapid, standardized protein extraction method using adaptive focused acoustics for identification of mycobacteria by MALDI-ToF MS.
abstract: Mycobacterial identification using MALDI-ToF MS (MALDI) has been hindered by inadequate extraction methods. Adaptive Focused Acoustics™ uses concentrated ultrasonic energy to achieve cellular disruption. Using this technology, we developed a rapid mycobacterial inactivation/protein extraction method for MALDI-based identification. Agreement for identification to the species level versus conventional identification was stratified by log confidence cut-offs of ≥2.0, ≥ 1.8, or ≥1.7. A total of 182 mycobacterial isolates were tested. Complete inactivation of all species/strains was achieved after 2min. Using a log confidence cut-off of ≥2.0, overall agreement for the commercial method (CM) was 41.7% versus 66.7% for the novel method (NM). For the CM, agreement increased to 66.7% and 83.3% using log confidence cut-offs of ≥1.8 and ≥1.7, respectively; for the NM, agreement was 100% for both cut-offs with all isolates. With no alteration to the existing database, overall agreement for the NM was 83.4%, largely due to low scores for clinical isolates of M. chelonae and M. mucogenicum. Addition of spectra from a single clinical strain of each species to the existing database increased overall agreement to 93.1%.
authors: Department of Pathology, Division of Medical Microbiology, The Johns Hopkins Medical Institutions, Baltimore, MD, USA.
authors: La'Tonzia L
authors: LL
authors: Adams
authors: Department of Pathology, Division of Medical Microbiology, The Johns Hopkins Medical Institutions, Baltimore, MD, USA.
authors: Kim
authors: K
authors: Dionne
authors: Department of Pathology, Division of Medical Microbiology, The Johns Hopkins Medical Institutions, Baltimore, MD, USA.
authors: Stephanie
authors: S
authors: Fisher
authors: Department of Pathology, Division of Medical Microbiology, The Johns Hopkins Medical Institutions, Baltimore, MD, USA. Electronic address: nparrish@jhmi.edu.
authors: Nicole
authors: N
authors: Parrish
mesh_terms: D001426:Bacterial Proteins / Q000032:analysis* / Q000302:isolation & purification*; D004203:Disinfection / Q000379:methods / Q000592:standards; D006801:Humans; D050296:Microbial Viability / Q000528:radiation effects; D009161:Mycobacterium / Q000737:chemistry* / Q000145:classification* / Q000302:isolation & purification / Q000528:radiation effects; D009164:Mycobacterium Infections / Q000175:diagnosis / Q000382:microbiology; D013048:Specimen Handling / Q000379:methods / Q000592:standards*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D000069453:Ultrasonic Waves
chemical_list: D001426:Bacterial Proteins
keywords: MALDI ToF MS; Mycobacterial identification; Ultrasonication