NIH Research Festival
Objectives: Helicobacter pylori (Hp) is the primary cause of gastric cancer but we have little understanding of its relative abundance in the stomach compared to other taxa, especially at the time of gastric cancer diagnosis. New methods for characterizing bacterial communities may bring additional insight into the gastric microbiota. Methods: A total of 80 pairs (non-malignant and tumor) of gastric tissue samples from China and 80 pairs from Mexico were sampled from gastric cancer cases. We characterized the bacterial taxonomic profiles by sequencing the 16S rRNA gene V3-V4 region and the functional profiles by prediction with PICRUSt. Results: Based on non-malignant tissues, Hp was the most abundant member of gastric microbiota with average relative abundance of 51% in Chinese and 24% in Mexico. The relative abundance of Hp exceeded 50% in 53% Chinese and 28% of Mexican cases. Other than Helicobacter, gastric microbiota of both Chinese and Mexican cases was dominated by oral-associated bacteria genera including Streptococcus, Prevotella, and Haemophilus. After Helicobacter reads were removed, the taxonomic profiles of gastric microbiota resembled oral microbiota, the predicted functional profiles, however, did not resemble the body sites characterized by the Human Microbiome Project. Gastric microbiota composition did not differ by Hp colonization status or stomach anatomic site, but did differ between non-malignant and tumor tissue in either Chinese or Mexican samples. Conclusions: Our findings provided important insight on gastric microbiota composition of gastric cancer cases, and may have important clinical implications.
Scientific Focus Area: Epidemiology
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