Page 168 - HA Convention 2015

Parallel Sessions

PS3.6 Allied Health II – Technology Advancement and Innovation 13:15 Theatre 2

Matrix-assisted Laser Desorption Ionization Time of Flight Mass Spectrometry: A New Era in Diagnostic Microbiology
Wong BKC
Department of Pathology, United Christian Hospital, Hong Kong

Tuesday, 19 May Introduction

Conventional methods of bacterial and yeast identification are labour intensive and time consuming (18 to 24 hours). Matrix-
assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) is a new technology for accurate,
efficient (5 to 20 minutes) and high-throughput identification (less than two hours for 96 isolates). Rapid identification of
pathogens enables earlier appropriate treatment and infection control.

Objectives

To evaluate the accuracy of MALDI-TOF MS in clinical microbiology diagnosis by comparing it with commonly-used
conventional biochemical tests.

Methodology

182 bacterial and 8 yeast strains from clinical specimens, standard strains and quality assurance programme samples were
tested by comparing MALDI-TOF MS with the conventional identification method based on biochemical tests. Discrepant
results were confirmed by Vitek, API, or 16S rRNA gene sequencing. Direct bacterial detection from positive blood culture
bottles by MALDI-TOF MS was also evaluated.

Results

For 190 isolates, 180 (94.7%) isolates were accurately identified at the species level by using MALDI-TOF MS, and 10 (5.3%)
isolates were identified at the genus level only. For conventional biochemical tests, 168 isolates (88.4%) were identified at
the species level, 14 isolates (7.4%) were identified at the genus level only, and 8 isolates (4.2%) were unidentified. The direct
detection from positive blood culture bottles shortened the time for pathogen detection to at least two working days.

Conclusion

MALDI-TOF MS has better performance than conventional biochemical tests in identifying bacteria and yeasts found routinely
in the clinical laboratory. It has the potential to provide shorter turn-around time to enhance timely patient management with
added advantage in lower consumable cost.

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