Microbial Colonization of the esophagus in patients with gastroesophageal reflux disease and Barrett's esophagus

Background: Barrett's esophagus (BE) arises from chronic gastroesophageal reflux disease (GERD). Patients have an increased risk of adenocarcinoma (AD), which is the seventh most common cause of cancer mortality. All AD develop from BE, and over the last 20 years there has been a marked increase in both BE and AD. The reasons are not known, however, as with some forms of gastric cancer, it is possible that there may be a bacterial etiology. The aims of this study were therefore to characterize microbial communities colonizing distal esophageal mucosae in individuals with GERD and BE, together with healthy controls. Methods: Biopsies were taken at endoscopy from 21 patients with BE, 11 patients with GERD and two controls with no esophageal disease. Bacteria were quantified by real-time PCR using genus and species specific primer sets. FISH in conjunction with confocal laser scanning microscopy (CLSM) was also used to investigate the spatial localization of these organisms in mucosal biofilms. Results: In all three subject groups, bacteroides/prevotella were the major colonizers. Higher numbers of veillonella, staphylococcus, bifidobacteria and lactobacillus were detected in Barrett's and controls, compared to GERD patients. High levels of Campylobacter spp. associated with tumor formation and enteritis in animals were also found in BE patients, but not in any of the controls. CLSM demonstrated that microorganisms in mucosal biofilms frequently occurred in microcolonies. Conclusions: Significant microbial colonization of the esophagus was observed in both BE patients and controls compared to individuals diagnosed with GERD. The presence of nitrate-reducing campylobacters in BE indicates that this could provide a link in the promotion of disease processes leading to AD.