title: Egg passage of rodshaped and coccoid forms of Helicobacter pylori: preliminary studies.
abstract: BACKGROUND
  We used egg passage of bacteria stored in water to evaluate the culturability of the coccoid form of Helicobacter pylori, as a complement to the results obtained from various animal models. Egg passage was performed, as it is a simple, rapid, and well-characterized old method by which to culture and evaluate culturability of bacteria compared to experiments in animal models. Egg passage has been used in such experiments since 1938 for isolation and growth of, for example, Rickettsiae sp. and Chlamydia sp.
  
  
  METHODS
  The rod-shaped form of H. pylori was produced by plate cultures for 4 and 7 days. The coccoid form of H. pylori was produced by culture on agar plates for 10 days, followed by storage in water. These preparations then were inoculated into the yolk sac of differently aged fertilized eggs.
  
  
  RESULTS
  Positive culture was obtained from 14 of 17 eggs (82%) inoculated with rod-shaped H. pylori compared to 0 of 22 eggs (0%) inoculated with the coccoid form.
  
  
  CONCLUSIONS
  Culturability of H. pylori is reduced when it converts into the coccoid form produced by starvation and age followed by storage in water for several weeks at room temperature. Egg passage did not raise the culturability of the coccoid form of H. pylori. Our study demonstrates some clear differences between fresh rods and stored cocci forms of H. pylori in terms of culturability when passed through eggs.
authors.affiliation: Department of Clinical Microbiology, University Hospital, Uppsala, Sweden.
authors.forename: H
authors.initials: H
authors.lastname: Enroth
authors.forename: L
authors.initials: L
authors.lastname: Engstrand
mesh_terms: D000818:Animals; D001431:Bacteriological Techniques; D002642:Chick Embryo; D016481:Helicobacter Infections / Q000635:transmission; D016480:Helicobacter pylori / Q000254:growth & development* / Q000648:ultrastructure; D011309:Preservation, Biological; D013696:Temperature; D014774:Virulence; D014867:Water; D015017:Yolk Sac / Q000382:microbiology*
chemical_list: D014867:Water