Assessing the diagnostic importance of nonviable bacterial cells in respiratory infections

Geraint Rogers, Franziska Stressmann, Garrit Koller, Thomas Daniels, Mary Carroll, Kenneth Bruce

Research output: Contribution to journalArticle

64 Citations (Scopus)

Abstract

Identification of bacteria in clinical samples is fundamental to combating infections. Modern molecular genetic approaches exploit nucleic acids signals from clinical samples. However, DNA-derived signals can originate from nonviable bacterial cells and, therefore, generate data that could be misinterpreted. Terminal restriction fragment length polymorphism profiling of cystic fibrosis sputum samples was combined with propidium monoazide (PMA) photo-induced cross-linking. PMA is highly membrane impermeant and is excluded from viable bacteria but readily penetrates dead cells. Exposure to a light source renders DNA in permeable cells incapable of contributing to polymerase chain reaction. PMA treatment was shown to effectively prevent dead bacteria, spiked into sputum samples, from contributing to profiles. Comparison of treated and untreated clinical samples indicated that dead bacterial cells significantly bias untreated profiles. These findings highlight the significant contribution that nonviable bacteria can make to DNA-based diagnostic analysis of clinical samples while providing a simple and effective means of avoiding such bias.
Original languageEnglish
Pages (from-to)133-141
Number of pages9
JournalDiagnostic Microbiology and Infectious Disease
Volume62
Issue number2
DOIs
Publication statusPublished - Oct 2008
Externally publishedYes

Keywords

  • Cystic fibrosis
  • Bacterial infections
  • Propidium monoazide
  • 16S rDNA
  • T-RFLP profiling

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