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Hypervirulent-host-associated Citrobacter rodentium cells have poor acid tolerance

Allen Smith1, Arvind A Bhagwat

  • 1Diet Genomics and Immunology and Laboratory, Henry A. Wallace Beltsville Agricultural Research Center, Agricultural Research Service, USDA, 10300 Baltimore Avenue, BARC-E, Beltsville, MD 20705-2350, USA.

Current Microbiology
|January 19, 2013
PubMed

Insights

Citrobacter rodentium can become hyperinfectious after passing through mice. However, these hypervirulent cells are surprisingly acid-sensitive, challenging the role of stomach acidity in this phenomenon.

Area of Science:

  • Microbiology
  • Pathogen Biology
  • Infectious Diseases

Background:

  • Enteric food-borne pathogens can increase virulence after mammalian host passage.
  • Citrobacter rodentium is a mouse model for enterohemorrhagic Escherichia coli infections, known to develop hyperinfectivity.
  • The mechanisms underlying C. rodentium hypervirulence require further investigation.

Purpose of the Study:

  • To investigate if increased acid tolerance explains the hypervirulent status of C. rodentium after host passage.
  • To determine the effect of in vitro acid adaptation and anaerobic growth on fecal components on C. rodentium infectivity.

Main Methods:

  • Passaging C. rodentium through a mouse gastrointestinal tract to induce hypervirulence.
  • Culturing C. rodentium under mildly acidic conditions (pH 5.5) to assess acid tolerance.
  • Evaluating the infectivity of adapted C. rodentium strains in a mouse model.
  • Culturing C. rodentium anaerobically on fecal components.

Main Results:

  • A hyperinfectious state of C. rodentium was observed after host passage.
  • Hypervirulent C. rodentium cells exhibited extreme acid sensitivity.
  • Growth in mildly acidic conditions induced acid tolerance but did not enhance infection establishment.
  • Anaerobic growth on fecal components did not induce hypervirulence.

Conclusions:

  • Hypervirulent C. rodentium is paradoxically acid-sensitive, not acid-tolerant.
  • Mouse gastric acidity alone is insufficient to explain the hypervirulent phenotype of C. rodentium.
  • Further research is needed to elucidate the factors contributing to C. rodentium hypervirulence.

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