title: An alternative, sensitive method to detect Helicobacter pylori DNA in feces.
abstract: BACKGROUND
  Despite the high sensitivity and specificity of PCR, detection of Helicobacter pylori DNA in feces is still challenging. Fecal samples contain inhibitory molecules that can prevent amplification of the target DNA. Even by using specific DNA extraction kits for stools, monitoring of infection by analyzing stool samples remains problematic and endorses the need for improved diagnostic methods.
  
  
  METHODS
  The newly proposed method uses selective hybridization of target DNA with biotin-labeled probes, followed by DNA isolation with streptavidin-coated magnetic beads. After three washing steps, the purified DNA can be amplified immediately using conventional or quantitative PCR. In order to test this technique on biological samples, Mongolian gerbils were infected with H. pylori ATCC 43504 and fecal samples were analyzed on days 1, 4, and 10 post infection.
  
  
  RESULTS
  A detection limit of one bacterial cell per 100 mg stool sample was established, but only after removal of the magnetic beads from the target DNA by heating. This resulted in a 10-fold increase of sensitivity compared to a commercially available stool DNA extraction kit. Analysis of fecal samples from infected gerbils demonstrated the presence of H. pylori DNA on each time point, while the uninfected animal remained negative.
  
  
  CONCLUSIONS
  The proposed technique allows detection of very low quantities of H. pylori DNA in biological samples. In laboratory animal models, detailed monitoring of infection and complete clearance of infection can be demonstrated thanks to the low detection limit.
authors: Laboratory of Microbiology, Parasitology, and Hygiene (LMPH), Faculty of Pharmaceutical, Biomedical, and Veterinary Sciences, University of Antwerp, Antwerp, Belgium.
authors: Tessa
authors: T
authors: Horemans
authors: Maartje
authors: M
authors: Deschacht
authors: Sofie
authors: S
authors: Clais
authors: John
authors: J
authors: Van Camp
authors: Pim
authors: P
authors: de Rijk
authors: Jan
authors: J
authors: Holvoet
authors: Tim
authors: T
authors: Van Assche
authors: Louis
authors: L
authors: Maes
authors: Paul
authors: P
authors: Cos
mesh_terms: D000328:Adult; D000818:Animals; D004269:DNA, Bacterial / Q000235:genetics*; D005243:Feces / Q000382:microbiology*; D005260:Female; D005849:Gerbillinae; D016480:Helicobacter pylori / Q000235:genetics* / Q000302:isolation & purification*; D006801:Humans; D008297:Male; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics
chemical_list: D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S