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Use of matrix assisted laser desorption ionisation–time of flight mass spectrometry in a paediatric clinical laboratory for identification of bacteria commonly isolated from cystic fibrosis patients
  1. Ankita Patel Desai1,
  2. Theresa Stanley2,
  3. Maria Atuan2,
  4. Jonelle McKey2,
  5. John J LiPuma3,
  6. Beverly Rogers2,4,
  7. Robert Jerris2,4
  1. 1Department of Pediatric Infectious Diseases, Emory University School of Medicine, Atlanta, Georgia, USA
  2. 2Department of Pathology, Children's Healthcare of Atlanta, Atlanta, Georgia, USA
  3. 3Department of Pediatrics, University of Michigan, Ann Arbor, Michigan, USA
  4. 4Department of Pathology, Emory University School of Medicine, Atlanta, Georgia, USA
  1. Correspondence to Dr Ankita Patel Desai, Pediatric Infectious Diseases Fellow, Emory University School of Medicine, 2015 Uppergate Drive, Atlanta, GA 30322, USA; ankita.desai{at}emory.edu

Abstract

Background Matrix-assisted laser desorption ionisation–time of flight mass spectrometry (MALDI-TOF MS) has been described as a rapid, accurate method for bacterial identification.

Aims To investigate the ability of the technique, using the unamended database supplied with the system, to identify bacteria commonly isolated in cystic fibrosis (CF) patients.

Methods Organisms commonly isolated from CF patients identified by MALDI-TOF MS were compared to conventional phenotypic and genotypic analyses. For MALDI-TOF MS, the direct colony technique was used routinely with one extraction procedure performed on a mucoid Pseudomonas aeruginosa. For 24 unique CF specimens, workload comparison and time to identification were assessed.

Results Of 464 tested isolates, conventional (phenotypic and genotypic) identification compared to MALDI-TOF MS showed complete genus, species agreement in 92%, with genus agreement in 98%. This included 29 isolates within the Burkholderia cepacia complex. All 29 were correctly identified to the genus level and 24 of these were speciated. Time to identification with 47 bacterial isolates from 24 CF patients showed identification of 85% of isolates by MALDI-TOF MS at 48 h of incubation, compared to only 34% with conventional methods.

Conclusions Using the unamended database supplied with the system, MALDI-TOF MS provides rapid and reliable identification of bacteria isolated from CF specimens. Time to identification studies showed that the use of same day, same method for organism identification will decrease time to result and optimise microbiology workflow.

  • MALDI-TOF MS
  • cystic fibrosis
  • bacterial identification
  • microbiology
  • microbial genetics
  • laboratory tests
  • clinical infectious diseases
  • antimicrobial resistance
  • Helicobacter pylori
  • MRSA

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Footnotes

  • A preliminary report of this work was presented at the 110th General Meeting of the American Society for Microbiology in May 2010 in San Diego, California.

  • Funding This work was supported by a grant from Bruker Daltonics, Billerica, Massachusetts, USA. The company supplied the MALDI-TOF MS instrument, reagent support and funds for technical support. They were not involved in experimental design, data analysis or manuscript preparation.

  • Competing interests None.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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