Microbial Identification Using MALDI-TOF MS

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Coauthors: Heather MacDonald, M(ASCP), MB(ASCP) and Robert C. Jerris, PhD, D(ABMM)
Reviewer: Judi Bennett, MT, BSM

This course will briefly describe the basic principles of MALDI-TOF MS through the pre-analytical, analytical, and post-analytical phases and update the laboratorian to current applications of this technique.

Continuing Education Credits


  • Define matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS).
  • Name the three major functional components of the MS instrument.
  • Describe two ways to justify purchase/acquisition of a MALDI-TOF MS system.
  • List three key technical methods used in preparing organisms for identification by MALDI-TOF MS.
  • Describe microbial growth requirements (media and incubation parameters) suitable for analysis by MALDI-TOF MS.
  • Identify key processes for post-analytical reporting.
  • Summarize current regulatory requirements when performing MALDI-TOF MS.

Course Outline

  • Pretest Questions
      • What are the three key/major components of a MALDI-TOF MS instrument?
      • MALDI-TOF MS can be used to identify which of the following organisms?
      • MALDI-TOF MS instruments are used exclusively in the research setting and when using them in the clinical laboratory to report identifications, they r...
      • Because of the extensive database, many organisms identified by MALDI-TOF MS in the clinical laboratory may not be familiar to technologists.
  • Introduction to MALDI-TOF MS
      • Introduction
  • MALDI-TOF MS: Basic Concept
      • Basic Concept
      • Place the steps below in sequential order, as they would occur when using MALDI-TOF MS technology.
  • Pre-analytical
      • Pre-analytical Considerations
    • Cost Justification
      • Cost Justification
      • Using MALDI-TOF MS identification for early diagnosis of gram-negative bacteremia, compared to phenotypic tests, increases the result turnaround time ...
    • Selection of Instrument
      • Instrument Selection
      • Instrument Comparison
      • Instrument Comparison, continued
      • Which of these MALDI-TOF MS systems are FDA-cleared and available in the United States?
  • Regulation, Accreditation, and Best Practice
      • Food and Drug Administration (FDA)
      • College of American Pathologists (CAP)
      • Verification and Validation of MALDI-TOF MS Performance
      • Clinical laboratories must verify or validate instrumentation and the associated databases prior to utilization for clinical diagnostics.
  • Analytical
    • Test Performance
      • Template (Target Plate)
    • Growth and Incubation Requirements
      • Media: Solid versus Liquid
      • Selective versus Nonselective Culture Media
      • Incubation Conditions
    • Preparation/Extraction Techniques
      • Specimen Preparation-Direct Spotting
      • On-Plate Extraction Method (Formic Acid Overlay)
      • Full Extraction (In-Tube, ethanol, formic acid method)
    • Matrix
      • Matrix
    • Workflow
      • Key Workflow Factors: LIS and Instrument Interface
      • Key Workflow Factors: Centralized versus Decentralized MALDI-TOF MS Processing
      • Which best describes the type of workflow approach that relies on a single laboratory station to process the target plate?
    • Quality Control
      • Quality Control Measures
      • What approximate concentration of organism is needed in order to achieve a valid identification?
    • Direct from Blood Culture MALDI-TOF MS
      • Identification from Positive Blood Culture Bottles
      • The MALDI-TOF MS can identify which of the following organisms? (Select all that apply.)
  • Post-analytical
      • Post-Analytical Considerations
      • Shigella and Escherichia coli are so closely related that they cannot be distinguished by MALDI-TOF MS.
  • Safety
      • Safety Considerations
  • Summary
      • Summary
  • References
      • References

Additional Information

Level of instruction: Beginning
Author information: Heather MacDonald, M(ASCP), MB(ASCP) has over 10 years of clinical laboratory experience and oversees a Molecular Diagnostics Laboratory. She is currently the Advanced Diagnostics Manager for Children's Healthcare of Atlanta in Georgia. Along with performing routine diagnostic assays, implementing laboratory-developed qualitative and quantitative molecular assays (both singleplex and multiplex) is her primary focus. Heather has published numerous articles and presents her research at national and international meetings. She has also worked with numerous corporations to bring commercial assays to market.
Coauthor information: Robert C. Jerris, PhD, D(ABMM) is currently the Medical Director of Clinical Microbiology, Children's Healthcare of Atlanta in GA. He is also an Adjunct Associate Professor at the Emory University School of Medicine, in Atlanta, GA. Dr. Jerris has directed clinical microbiology and molecular diagnostic laboratories for over 30 years. In that time, he has developed and brought to market a number of clinical laboratory systems and assays. He is well published and presents his research at national and international meetings. As current Chair for the American Society of Microbiology's Professional Affairs Committee, Dr. Jerris is committed to the workforce and regulatory oversight for clinical laboratories.
Reviewer information: Judi Bennett MT, BSM is currently a Program Director for MediaLab, Inc. in Lawrenceville, GA. She has over 30 years of medical laboratory experience in an acute care hospital setting as Laboratory Manager, Senior Clinical Applications Specialist, Point-of-Care Coordinator, Microbiology Supervisor, and generalist technologist. Judi has been a speaker at various conferences and has been published in peer-reviewed publications.
Course description:  This course will briefly describe the basic principles of MALDI-TOF MS through the pre-analytical, analytical, and post-analytical phases and update the laboratorian to current applications of this technique. 

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This course is part of:
Reusable target plate
Time of Flight
Target Plate Loaded
MALDI TOF MS Cost justification