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Calcium requirement and virulence of Yersinia enterocolitica

P A Berche, P B Carter

    Journal of Medical Microbiology
    |August 1, 1982
    PubMed

    Insights

    Highly virulent Yersinia enterocolitica requires calcium for virulence at 37°C. Loss of this calcium dependence results in avirulence, suggesting induced avirulent mutants are key to Yersinia enterocolitica pathogenesis.

    Area of Science:

    • Microbiology
    • Bacterial Pathogenesis
    • Molecular Biology

    Background:

    • Yersinia enterocolitica is an important foodborne pathogen.
    • Virulence of Yersinia enterocolitica is temperature-dependent.
    • Calcium metabolism plays a role in bacterial virulence.

    Purpose of the Study:

    • To investigate the role of calcium in the virulence of Yersinia enterocolitica serotype O:8.
    • To determine if calcium dependence is a characteristic of virulent Yersinia enterocolitica strains.
    • To explore the genetic basis of calcium dependence in Yersinia enterocolitica.

    Main Methods:

    • In vitro growth assays at different temperatures and calcium concentrations.
    • Virulence testing in a mouse model using intravenous inoculation.
    • Generation and characterization of calcium-independent mutants.
    • Fluctuation tests to assess mutation rates.

    Main Results:

    • Highly virulent Yersinia enterocolitica strains (LD50 < 10^3) exhibit in vitro calcium dependence at 37°C, but not at 26°C.
    • Avirulent strains (LD50 > 10^7) do not show calcium dependence.
    • Growth on calcium-depleted media at 37°C yields avirulent, calcium-non-requiring mutants (0.5-6%) and virulent, calcium-dependent variants.
    • Calcium-non-requiring mutants are rapidly cleared in mice, while calcium-dependent variants remain virulent.
    • Infected organ homogenates yield calcium-non-requiring colonies on calcium-depleted media.
    • Fluctuation tests suggest induced avirulence rather than spontaneous mutation.

    Conclusions:

    • Calcium dependence at 37°C is a critical factor for the high virulence of Yersinia enterocolitica serotype O:8.
    • Loss of calcium dependence leads to avirulence, with mutants being rapidly cleared in vivo.
    • The emergence of avirulent, calcium-non-requiring mutants appears to be an induced phenomenon.
    • This study highlights the intricate relationship between environmental conditions, nutrient availability, and bacterial virulence mechanisms.

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