Brief Articles
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World J Gastroenterol. Jan 28, 2009; 15(4): 484-488
Published online Jan 28, 2009. doi: 10.3748/wjg.15.484
Application of Stool-PCR test for diagnosis of Helicobacter pylori infection in children
Tahereh Falsafi, Raha Favaedi, Fatemeh Mahjoub, Mehri Najafi
Tahereh Falsafi, Raha Favaedi, Department of Biology, Alzahra University, 1993891176 Tehran, Iran
Fatemeh Mahjoub, Mehri Najafi, Department of Gastro-enterology and Pathology, Medical Center for Children, Tehran 15614, Iran
Author contributions: Falsafi T designed the study and wrote the manuscript, also provided vital analytical tools; Favaedi R performed the majority of experiments; Najafi M provided the biopsies and patient related information; Mahjoub F performed histopathological study of the biopsies.
Correspondence to: Tahereh Falsafi, Department of Biology, Azzahra University, Deh Vanak, 1993891176 Tehran, Iran. tfalsafi@yahoo.com
Telephone: +98-21-88058912
Fax: +98-21-88058912
Received: November 12, 2008
Revised: December 25, 2008
Published online: January 28, 2009
Abstract

AIM: To evaluate the usefulness of stool-PCR test for diagnosis of Helicobacter pylori (H pylori) infection in pediatric populations.

METHODS: Based on endoscopic features (including nodular gastritis, erosive duodenitis and ulcer) and/or a positive rapid urease test (RUT) obtained during endoscopy, 28 children from a group of children admitted to the Children's Medical Center of Tehran for persistent upper gastrointestinal problems were selected to compare biopsy-based tests with stool-PCR. Their gastric activity and bacterial density were graded by the updated Sydney system, and their first stool after endoscopy was stored at -70°C. Biopsies were cultured on modified campy-blood agar plates and identified by gram-staining, biochemical tests, and PCR. Two methods of phenol-chloroform and boiling were used for DNA extraction from H pylori isolates. Isolation of DNA from stool was performed using a stool DNA extraction kit (Bioneer Inc, Korea). PCR was performed using primers for detection of vacA, cagA, and 16srRNA genes in both isolates and stool.

RESULTS: Sixteen out of 28 child patients (57%) were classified as H pylori positive by biopsy-based tests, of which 11 (39%) were also positive by stool-PCR. Sensitivity and specificity of stool-PCR was 62.5% and 92.3% respectively. H pylori was observed in histological sections for 10 out of 11 stool-positive patients. Association was observed between higher score of H pylori in histology and positivity of stool-PCR. Also association was observed between the more severe form of gastritis and a positive stool-PCR.

CONCLUSION: Association between higher score of H pylori in histology and a positive stool-PCR make it a very useful test for detection of H pylori active infection in children. We also suggest that a simple stool-PCR method can be a useful test for detection of H pylori virulence genes in stool.

Keywords: Helicobacter pylori; Non-invasive diagnosis; Stool-PCR; Histology; Score; Children; Iran