MSACL 

Microorganism Identification by MALDI in a Clinical Lab
Tue 3:30 PM - Track 2: Microbes and Infectious Disease
Steve Drake
National Institutes of Health
Steve Drake, National Institutes of Health
Identification of microorganisms in the clinical laboratory is based traditionally on morphology and biochemical characteristics. For many species, identification may take days so a rapid species-specific method would improve patient care. Nucleic-acid based assays are sensitive and accurate methods for species identification but are relatively slow and labor intensive. MALDI-TOF mass spectrometry was evaluated for the rapid identification of microorganisms using Bruker Daltonics MALDI BioTyper software and either an in-house generated spectral library of 105 yeast reference strains or the manufacturer's library consisting mainly of bacteria.

In total, 86% of 115 yeast, 562 bacterial, and 210 blood isolates were correctly identified. Of the remainder, 12% were not identified, probably due to sample prep or low organism count, and 2% were identified as belonging to groups known by the manufacturer to be indistinguishable. Given these results, MALDI-TOF compares favorably to current techniques but MALDI-TOF is considerably faster and cheaper, thus making MALDI-TOF identification of microorganisms a preferred method for the routine identification of microorganisms. Considerations for using this method as a primary method for organism identification of clinical samples will be discussed.
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