Insights into the blood, gut, and oral microbiomes of myocardial infarction patients

Background A growing body of evidence links shifts in blood microbial composition with cardiovascular diseases, particularly myocardial infarction (MI). Recent studies have raised questions regarding a core blood microbiome's existence, positing that microbes may translocate from the gut or oral cavities into the bloodstream. To test this hypothesis, here we examined the blood, gut, and oral microbiome composition in a cohort of MI patients and healthy people (HP). Methods A total of 144 samples were collected from 48 participants, including blood, stool, and saliva from 24 HP and 24 MI patients. The samples were then analyzed using 16S rRNA gene sequencing to achieve comprehensive microbial profiling. Results Our findings revealed significant shifts in the gut and oral microbiome composition between both groups. Notably, MI patients exhibited a distinct increase in the abundance of Selenomonadaceae, Enterobacterales, and Dialister within their gut microbiota. Similarly, their oral microbiomes showed elevated levels of Actinobacteriota, Streptococcaceae, Micrococcaceae, Coriobacteriaceae, and the genera Streptococcus, Rothia , and Granulicatella . Our findings also revealed potential associations between specific bacteria and MI markers. Gut bacteria such as Lachnospirales, Clostridia, Enterobacterales, Selenomonadaceae, Bifidobacteriales, Bifidobacterium , Lachnospiraceae, and Blautia , along with oral bacteria like Fusobacteriaceae, Fusobacterium , Fusobacteriales, and Fusobacteria, show links to MI markers including triglycerides, LDL, neutrophils, hemoglobin, uric acid, fasting blood glucose, platelets, and total cholesterol. Conversely, analyses of the blood microbiome revealed no notable distinctions in alpha diversity, beta diversity, or predicted functional pathways between the groups. Conclusion This study identifies distinct shifts in the gut and oral microbiomes of MI patients, with specific bacteria linked to key MI markers, underscoring a potential gut-oral-cardiovascular axis in disease progression. The lack of unique blood microbiome signatures supports microbial translocation rather than a stable blood microbiome, highlighting the gut and oral microbiota as key players in cardiovascular health.