The significance of cagA

The significance of cagA + Helicobacter pylori in reflux oesophagitis

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  1. V J Warburton-Timmsa,
  2. A Charlettd,
  3. R M Valorib,
  4. J S Uffc,
  5. N A Shepherdc,
  6. H Barrb,
  7. C A M McNultya
  8. aPublic Health Laboratory, Gloucestershire Royal Hospital, Gloucester, UK, bGloucester Gastroenterology Group, Gloucestershire Royal Hospital, Gloucester, UK, cDepartment of Histopathology, Gloucestershire Royal Hospital, Gloucester, UK, dPHLS Statistics Unit, 61 Colindale Avenue, London, UK
  9. Dr C A M McNulty, Public Health Laboratory, Gloucestershire Royal Hospital, Great Western Road, Gloucester GL1 3NN, UK. jwhiting{at}phls.nhs.uk

Abstract

BACKGROUND Helicobacter pylori is a gastroduodenal pathogen associated with ulceration, dyspepsia, and adenocarcinoma. Recent preliminary studies have suggested that H pylori may be protective for oesophageal adenocarcinoma. In addition, strains of_H pylori_ identified by the presence of the cytotoxin associated gene A (cagA) are shown to have a significant inverse association with oesophageal adenocarcinoma. Given that cagA + H pylori may protect against oesophageal carcinoma, these strains may be protective for oesophagitis, a precursor of oesophageal carcinoma.

AIMS The aim of this study was to investigate the association between_cagA_ + H pylori and endoscopically proved oesophagitis.

PATIENTS The study group included 1486 patients attending for routine upper gastrointestinal tract endoscopy.

METHODS At endoscopy the oesophagus was assessed for evidence of reflux disease and graded according to standard protocols. Culture and histology of gastric biopsy specimens determined H pylori status. The prevalence of cagA was identified by an antibody specific ELISA (Viva Diagnostika, Germany).

RESULTS H pylori was present in 663/1485 (45%) patients and in 120/312 (38%) patients with oesophagitis. Anti-CagA antibody was found in 499/640 (78%) H pylori positive patients. Similarly, anti-CagA antibody was found in 422/521 (81%) patients with a normal oesophagus and in 42/60 (70%) with mild, 24/35 (69%) with moderate, and 11/24 (46%) with severe oesophagitis. The risk of severe oesophagitis was significantly decreased for patients infected with_cagA_ + H pylori after correction for confounding variables (odds ratio 0.57, 95% confidence interval 0.41–0.80; p=0.001).

CONCLUSIONS These results suggest that infection by_cagA_ + H pylori may be protective for oesophageal disease.

cag
cytotoxin associated gene
cagA, cytotoxin associated gene A
PAI, pathogenicity island
GORD
gastro-oesophageal reflux disease
NSAID
non-steroidal anti-inflammatory drug
PPI
proton pump inhibitor
LOS
lower oesophageal sphincter

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