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Rapid Identification of Bacteria in Positive Blood Culture Broths by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry

Year: 2009

Type: article

Abstract: Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry is a rapid, accurate method for identifying bacteria and fungi recovered on agar culture media. We report herein a method for the direct identification of bacteria in positive blood culture broths by MALDI-TOF mass spectrometry. A total of 212 positive cultures were examined, representing 32 genera and 60 species or groups. The identification of bacterial isolates by MALDI-TOF mass spectrometry was compared with biochemical testing, and discrepancies were resolved by gene sequencing. No identification (spectral score of < 1.7) was obtained for 42 (19.8%) of the isolates, due most commonly to insufficient numbers of bacteria in the blood culture broth. Of the bacteria with a spectral score of > or = 1.7, 162 (95.3%) of 170 isolates were correctly identified. All 8 isolates of Streptococcus mitis were misidentified as being Streptococcus pneumoniae isolates. This method provides a rapid, accurate, definitive identification of bacteria within 1 h of detection in positive blood cultures with the caveat that the identification of S. pneumoniae would have to be confirmed by an alternative test.

Source: Journal of Clinical Microbiology

DOI: 10.1128/jcm.01541-09

Authors: Lindsay G. Stevenson, Steven K. Drake, Patrick R. Murray

Institutions: National Institutes of Health, National Institutes of Health Clinical Center

Language: English

Topic: Bacterial Identification and Susceptibility Testing

Subfield: Microbiology (medical)

Field: Medicine

Domain: Health Sciences

SDG: Good health and well-being

Open Access status: green

Funder: National Institutes of Health