title: Determination of Helicobacter pylori vacA allelic types by single-step multiplex PCR.
abstract: OBJECTIVE
  To develop and evaluate a novel multiplex PCR assay that enables definition of Helicobacter pylori vacA allelic type in a single reaction.
  
  
  RESULTS
  Application of the one-step system to DNA extracts from 22 cultures of known vacA genotype demonstrated that it was highly accurate. Analysis of 15 matched gastric biopsy/culture pairs generated exactly correlating genotype profiles. vacA genotypes were determined from an additional 62/70 gastric biopsies from dyspeptic patients of known H. pylori positive status by the one-step assay, compared with 63/70 by the original two-reaction test. Types s1/m1, s1/m2 and s2/m2 were identified in 51.9%, 31.2% and 16.9% of biopsies, respectively.
  
  
  CONCLUSIONS
  The multiplex PCR system developed enables rapid one-step vacA genotyping that is accurate, easy to interpret and more economical than the alternative multiple-reaction tests. Application of this system to gastric biopsies from patients in South-east England demonstrated that s1/m1 was the most common genotype, while s1/m2 and s2/m2 were less prevalent.
  
  
  CONCLUSIONS
  This simple one-step system can be applied direct to antral gastric biopsies without the need for culture, thereby facilitating rapid surveillance of vacA genotype in relation to geographical location and disease status.
authors.affiliation: Laboratory of Enteric Pathogens, Central Public Health Laboratory, London, UK. schisholm@phls.nhs.uk
authors.forename: S A
authors.initials: SA
authors.lastname: Chisholm
authors.forename: E L
authors.initials: EL
authors.lastname: Teare
authors.forename: B
authors.initials: B
authors.lastname: Patel
authors.forename: R J
authors.initials: RJ
authors.lastname: Owen
mesh_terms: D000483:Alleles; D001426:Bacterial Proteins / Q000235:genetics*; D001706:Biopsy; D004269:DNA, Bacterial / Q000032:analysis; D005753:Gastric Mucosa / Q000382:microbiology; D005838:Genotype; D016481:Helicobacter Infections / Q000382:microbiology; D016480:Helicobacter pylori / Q000145:classification / Q000235:genetics*; D006801:Humans; D016133:Polymerase Chain Reaction / Q000379:methods*; D012680:Sensitivity and Specificity
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; C074689:VacA protein, Helicobacter pylori