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. 2005 Dec 14;11(46):7277-83.
doi: 10.3748/wjg.v11.i46.7277.

Bacterial Biota in Reflux Esophagitis and Barrett's Esophagus

Free PMC article

Bacterial Biota in Reflux Esophagitis and Barrett's Esophagus

Zhiheng Pei et al. World J Gastroenterol. .
Free PMC article


Aim: To identify the bacterial flora in conditions such as Barrettos esophagus and reflux esophagitis to determine if they are similar to normal esophageal flora.

Methods: Using broad-range 16S rDNA PCR, esophageal biopsies were examined from 24 patients [9 with normal esophageal mucosa, 12 with gastroesophageal reflux disease (GERD), and 3 with Barrettos esophagus]. Two separate broad-range PCR reactions were performed for each patient, and the resulting products were cloned. In one patient with Barrettos esophagus, 99 PCR clones were analyzed.

Results: Two separate clones were recovered from each patient (total = 48), representing 24 different species, with 14 species homologous to known bacteria, 5 homologous to unidentified bacteria, and 5 were not homologous (<97% identity) to any known bacterial 16S rDNA sequences. Seventeen species were found in the reflux esophagitis patients, 5 in the Barrettos esophagus patients, and 10 in normal esophagus patients. Further analysis concentrating on a single biopsy from an individual with Barrettos esophagus revealed the presence of 21 distinct bacterial species. Members of four phyla were represented, including Bacteroidetes, Firmicutes, Proteobacteria, and Actinobacteria. Microscopic examination of each biopsy demonstrated bacteria in intimate association with the distal esophageal epithelium, suggesting that the presence of these bacteria is not transitory.

Conclusion: These findings provide evidence for a complex, residential bacterial population in esophageal reflux-related disorders. While much of this biota is present in the normal esophagus, more detailed comparisons may help identify potential disease associations.


Figure 1
Figure 1
Microscopic examination of bacterial cells in the esophagus. Esophageal biopsies were fixed in formalin, paraffin-embedded, sectioned, and examined by using Gram-Twort stain. A: In the biopsy from patient #265 with a normal esophagus, Gram-negative cocci and coccobacilli were tightly associated with the surface of squamous epithelial cells. B: In the biopsy from patient #246 with Barrett’s esophagus, Gram-positive cocci were highly concentrated within the lumen of an intestinal-type gland.
Figure 2
Figure 2
Phylogenetic analysis of bacterial 16S rDNA detected in the distal esophagus. Sequences were aligned using ClustalW, and subjected to phylogenetic analysis using Paup 4.0b10 neighbor-joining analysis, based on HKY85 distance matrices. Bootstrap values (based on 500 replicates) are represented at each node when >50%, and the branch length index is represented below the phylogram. Names of bacterial species closest in homology with the detected 16S rDNA are located at the termination of each branch. “Unidentified” oral bacterial clones are potential bacterial species whose phylogenetic positions were designated by PCR-amplified 16S sequences only, rather than based on cultured organisms. The serial number of a clone followed by percentage of homology with the closest DNA sequence in GenBank is used as the species name for 16S rDNA sequence with <97% identity with all known DNA sequences. The frequency that a species was detected and its sources are shown following the species name. ‘N’ represents normal esophagus, ‘E’ represents esophagitis, and ‘B’ represents Barrett’s esophagus. The 39 species belong to four phyla, as shown at the right.

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