Gut Microbiota Differences with Age and among North American, European, and Australian Regions

The study analyzed the gut microbiota composition from over 3600 ambulatory donor samples undergoing routine medical evaluation from the USA, Canada, UK, Denmark, Australia, New Zealand, and other regions, spanning ages from 2 to over 70 years using the GA-map® multiplex polymerase chain reaction assay. The research aimed to identify differences in dysbiosis index (DI) score, diversity, and gastrointestinal (GI) microbiota across age categories and regions. Bacterial DNA was extracted, followed by amplification, hybridization, and detection of target organisms. The DI score showed an inverse but nonsignificant change with age. Significantly reduced DI scores were observed in adult cohorts from the UK and Denmark compared to North America and Australia, likely due to reduced bacterial diversity. Nonsignificant reduction in bacterial diversity was observed in ages over 70 years. Bacterial species such as Actinobacteria, Bifidobacterium spp., Dialister invisus and Megasphaera micronuciformis, and Streptococcus salivarius spp. were more abundant in younger cohorts. Older donors showed increased abundance of Proteobacteria. In European and Australian cohorts, lower levels of Bacteroides spp. and Prevotella spp. were detected relative to the US among other differences. This study demonstrated significant age- and region-specific differences in gut microbiota composition in an ambulatory population free from GI pathogens, inflammation typically associated with irritable bowel syndrome or inflammatory bowel disease, or active diarrhea.