Abstract
BackgroundMatrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) is a new and revolutionary identification method for microorganisms and has recently been introduced into clinical microbiology in many industrialized countries in Europe and North America.ObjectivesOur study aimed to compare the performance and practicality of two commercial MALDI-TOF MS platforms in a head-to head manner at a routine laboratory in Chile.MethodsDuring a five-month period in 2012–13, the diagnostic efficiency (correct identification rate) and agreement between Microflex LT (Bruker Daltonics) and Vitek MS (bioMérieux) was compared in a parallel manner to conventional identification including genotypic analysis for difficult-to-identify strains. The study included 804 microbial isolates: 252 Enterobacteriaceae, 126 non-fermenters, 36 other gram-negative rods, 279 gram-positive cocci, 32 gram-positive rods, 32 anaerobes, and 47 yeasts. Other relevant factors of the two devices such as user friendliness and connectivity were also evaluated and compared.ResultsBoth systems correctly identified the vast majority (98%) of the isolates to the genus level. Vitek MS reached higher rates of identification to species and species complex level than Microflex LT (81% vs. 85% and 87% vs. 93%, respectively), which was mainly based on the higher performance among coagulase negative staphylococci and Candida isolates. The evaluation of user friendliness and other technical aspects showed only marginal differences, which slightly favored Vitek MS, mainly due to its ready-to-use supplies, easier connectivity and workflow integration, and availability of local technical support.ConclusionsBoth MALDI-TOF MS systems permitted fast and accurate identification of most microbial strains and showed a high level of user-friendliness. The observed differences were marginal and slightly favored Vitek MS, mainly due to practicality and connectivity issues within our setting.
Highlights
The identification of bacteria and yeasts in clinical samples has relied on phenotypical aspects such as morphology of colonies, microscopical appearance, and biochemical tests, which are time consuming and costly
Microflex LT (81% vs. 85% and 87% vs. 93%, respectively), which was mainly based on the higher performance among coagulase negative staphylococci and Candida isolates
Considering these limitations, matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) has the potential to revolutionize the identification of microorganisms in routine medical microbiology [2,3,4]
Summary
The identification of bacteria and yeasts in clinical samples has relied on phenotypical aspects such as morphology of colonies, microscopical appearance, and biochemical tests, which are time consuming and costly. For species that are difficult to identify by these techniques, the method of choice is genomic analysis including sequencing; still, such methods are not widely available and usually not part of routine identification [1] Considering these limitations, matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) has the potential to revolutionize the identification of microorganisms in routine medical microbiology [2,3,4]. Its basic principle is the generation of characteristic mass spectra allowing a rapid and reliable identification of clinically relevant microorganisms The application of this new technique has been subject to several reviews [5,6,7,8,9,10,11]. Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry (MS) is a new and revolutionary identification method for microorganisms and has recently been introduced into clinical microbiology in many industrialized countries in Europe and North America
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