Bacterial species and total bacterial load in the distal oesophagus in patients with and without clinical gastric reflux.

Aims: The purpose of this study is to compare distal oesophagus of persons with and without gastric reflux in terms of bacterial load and presence of certain bacterial species.

Methods And Results: Two biopsy specimens were obtained from the distal oesophagus at 5 cm above the gastroesophageal junction of each of the 50 patients (20 with normal oesophagus and 30 with reflux oesophagitis) under endoscopic examination and used for histological examination and DNA isolation. We used a real-time PCR-based assay to quantify the bacterial load and the presence of certain bacterial species from one of the biopsy samples. The biopsy specimens taken from the patients with reflux oesophagitis were consistent with gastroesophageal reflux disease (GERD). The bacterial load did not significantly differ between the groups (P < 0·005).

Conclusion: While there was no difference between the bacterial load in the two groups, variation was observed in bacterial species. Most of the bacteria identified in distal oesophagus of the patients with gastroesophageal reflux were Gram negative.

Significance And Impact Of The Study: The human oesophagus was considered sterile until quite recently. Molecular techniques displayed the presence of a diverse bacterial species in the oesophagus. Although it is known that dysbiosis in the oesophagus causes GERD, and that Barrett's oesophagus can trigger the development of oesophageal adenocarcinoma, its etiopathogenesis is not clear. A limited number of published studies support the importance of the present study.