Culturability of Mycobacterium tuberculosis cells isolated from murine macrophages: A bacterial growth factor promotes recovery

Sergey Biketov, Galina V. Mukamolova, Vasiliy Potapov, Evgeniy Gilenkov, Galina Vostroknutova, Douglas B. Kell, Michael Young, Arseny S. Kaprelyants

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Very little is known about the culturability and viability of mycobacteria following their phagocytosis by macrophages. We therefore studied populations of the avirulent 'Academia' strain of Mycobacterium tuberculosis isolated from murine peritoneal macrophage lysates several days post-infection in vivo. The resulting bacterial suspensions contained a range of morphological types including rods, ovoid forms and coccoid forms. Bacterial viability measured using the MPN method (dilution to extinction in liquid medium) was often much higher than that measured by CFU (plating on solid medium). Viability in the MPN assay was further enhanced when the Micrococcus luteus protein, Rpf, was incorporated into the liquid culture medium at picomolar concentrations. Rpf is an example of a family of autocrine growth factors found throughout the high G+C cohort of Gram-positive bacteria including M. tuberculosis. M. tuberculosis cells obtained from macrophages had altered surface properties, as compared with bacteria grown in vitro. This was indicated by loss of the ability to adsorb bacteriophage DS6A, a reduced tendency to form clumps, acquisition of ethidium bromide stainability following heat treatment, and loss of Rpf-mediated resuscitation following freezing and thawing. These results indicate that a proportion of 'unculturable' M. tuberculosis cells obtained from macrophages is either injured or dormant and that these cells may be recovered or resuscitated using Rpf in liquid medium. (C) 2000 Federation of European Microbiological Societies.
    Original languageEnglish
    Pages (from-to)233-240
    Number of pages7
    JournalFEMS Immunology and Medical Microbiology
    Volume29
    Issue number4
    DOIs
    Publication statusPublished - 2000

    Keywords

    • Growth factor
    • Macrophages
    • Mycobacterium tuberculosis
    • Non-culturability
    • Phage
    • Resuscitation

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