The significance of cagA⁺ Helicobacter pylori in reflux oesophagitis

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.