title: Purification of Helicobacter suis Strains From Biphasic Cultures by Single Colony Isolation: Influence on Strain Characteristics.
abstract: BACKGROUND
  Helicobacter (H.) suis causes gastritis and decreased weight gain in pigs. It is also the most prevalent non-Helicobacter pylori Helicobacter species in humans with gastric disease. H. suis is extremely fastidious, and so far, biphasic culture conditions were essential for isolation and culture, making it impossible to obtain single colonies. Hence, cultures obtained from an individual animal may contain multiple H. suis strains, which is undesirable for experiments aiming for instance at investigating H. suis strain differences.
  
  
  METHODS
  Pure cultures of H. suis were established by growing bacteria as colonies on 1% brucella agar plates, followed by purification and enrichment by biphasic subculture. Characteristics of these single colony-derived strains were compared with those of their parent strains using multilocus sequence typing (MLST) and by studying bacterium-host interactions using a gastric epithelial cell line and Mongolian gerbil model.
  
  
  RESULTS
  The purification/enrichment procedure required a nonstop culture of several weeks. For 4 of 17 H. suis strains, MLST revealed differences between parental and single colony-derived strains. For three of four single colony-derived strains tested, the cell death-inducing capacity was higher than for the parental strain. One single colony-derived strain lost its capacity to colonize Mongolian gerbils. For the four other strains tested, colonization capacity and histopathologic changes were similar to what has been described when using strains with only a history of limited biphasic culture.
  
  
  CONCLUSIONS
  A method was developed to obtain single colony-derived H. suis strains, but this procedure may affect the bacterial genotype and phenotype.
authors.affiliation: Department of Pathology, Bacteriology and Avian Diseases, Ghent University, Merelbeke, Belgium.
authors.forename: Jungang
authors.initials: J
authors.lastname: Liang
authors.affiliation: Department of Pathology, Bacteriology and Avian Diseases, Ghent University, Merelbeke, Belgium.
authors.forename: Ellen
authors.initials: E
authors.lastname: De Bruyne
authors.affiliation: Department of Pathology, Bacteriology and Avian Diseases, Ghent University, Merelbeke, Belgium.
authors.forename: Richard
authors.initials: R
authors.lastname: Ducatelle
authors.affiliation: Department of Pathology, Bacteriology and Avian Diseases, Ghent University, Merelbeke, Belgium.
authors.forename: Annemieke
authors.initials: A
authors.lastname: Smet
authors.affiliation: Department of Pathology, Bacteriology and Avian Diseases, Ghent University, Merelbeke, Belgium.
authors.forename: Freddy
authors.initials: F
authors.lastname: Haesebrouck
authors.affiliation: Department of Pathology, Bacteriology and Avian Diseases, Ghent University, Merelbeke, Belgium.
authors.forename: Bram
authors.initials: B
authors.lastname: Flahou
mesh_terms: D000818:Animals; D015373:Bacterial Typing Techniques; D002460:Cell Line; D002999:Clone Cells; D004195:Disease Models, Animal; D004847:Epithelial Cells; D005260:Female; D005756:Gastritis / Q000382:microbiology*; D005838:Genotype; D005849:Gerbillinae; D016481:Helicobacter Infections / Q000382:microbiology*; D018247:Helicobacter heilmannii / Q000235:genetics / Q000302:isolation & purification*; D006801:Humans; D058885:Multilocus Sequence Typing; D010641:Phenotype; D013552:Swine; D013553:Swine Diseases / Q000382:microbiology*
keywords: Helicobacter suis; phenotype; single colony isolation; strain typing