0
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: not found

      Identification of Gram-positive cocci by use of matrix-assisted laser desorption ionization-time of flight mass spectrometry: comparison of different preparation methods and implementation of a practical algorithm for routine diagnostics.

      Journal of Clinical Microbiology

      Algorithms, Bacteriological Techniques, methods, Gram-Positive Bacterial Infections, diagnosis, microbiology, Gram-Positive Cocci, chemistry, classification, isolation & purification, Humans, Prospective Studies, Specimen Handling, Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization

      Read this article at

      ScienceOpenPublisherPMC
      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          This study compared three sample preparation methods (direct transfer, the direct transfer-formic acid method with on-target formic acid treatment, and ethanol-formic acid extraction) for the identification of Gram-positive cocci with matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). A total of 156 Gram-positive cocci representing the clinically most important genera, Aerococcus, Enterococcus, Staphylococcus, and Streptococcus, as well as more rare genera, such as Gemella and Granulicatella, were analyzed using a Bruker MALDI Biotyper. The rate of correct genus-level identifications was approximately 99% for all three sample preparation methods. The species identification rate was significantly higher for the direct transfer-formic acid method and ethanol-formic acid extraction (both 77.6%) than for direct transfer (64.1%). Using direct transfer-formic acid compared to direct transfer, the total time to result was increased by 22.6%, 16.4%, and 8.5% analyzing 12, 48, and 96 samples per run, respectively. In a subsequent prospective study, 1,619 clinical isolates of Gram-positive cocci were analyzed under routine conditions by MALDI-TOF MS, using the direct transfer-formic acid preparation, and by conventional biochemical methods. For 95.6% of the isolates, a congruence between conventional and MALDI-TOF MS identification was observed. Two major limitations were found using MALDI-TOF MS: the differentiation of members of the Streptococcus mitis group and the identification of Streptococcus dysgalactiae. The Bruker MALDI Biotyper system using the direct transfer-formic acid sample preparation method was shown to be a highly reliable tool for the identification of Gram-positive cocci. We here suggest a practical algorithm for the clinical laboratory combining MALDI-TOF MS with phenotypic and molecular methods.

          Related collections

          Author and article information

          Journal
          23554198
          3716085
          10.1128/JCM.02654-12

          Comments

          Comment on this article