Evaluation of bacterial survival and phagocyte function with a fluorescence-based microplate assay

Michael U. Shiloh, Jia Ruan, Carl Nathan

Research output: Contribution to journalArticlepeer-review

98 Scopus citations


To compare antibacterial function in macrophages from mice deficient in the respiratory burst oxidase or inducible nitric oxide synthase, we developed a fluorescence-based microplate assay of bacterial survival. As bacteria grow, they convert a formulation of resazurin termed AlamarBlue from its nonfluorescent oxidized state to its fluorescent reduced state. The time required to achieve a given fluorescence is inversely proportional to the number of viable bacteria present when the dye is added. This relationship allows a precise, accurate assessment of bacterial numbers with greater sensitivity and throughput and at less cost than conventional assays. The assay facilitated quantification of the killing of Escherichia coli by S- nitrosoglutathione and hydrogen peroxide and of Salmonella typhimurium by human neutrophils and mouse macrophages. Mouse macrophages lacking the 91- kDa subunit of the respiratory burst oxidase were deficient in their ability to kill S. typhimurium, while those lacking inducible nitric oxide synthase were unimpaired.

Original languageEnglish (US)
Pages (from-to)3193-3198
Number of pages6
JournalInfection and immunity
Issue number8
StatePublished - 1997

ASJC Scopus subject areas

  • Parasitology
  • Microbiology
  • Immunology
  • Infectious Diseases


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