Distribution of gut microbiota and prognostic value in elderly patients with coronary atherosclerosis: a preliminary culture-based study

Abstract Objective This study aimed to characterize the distribution of specific cultivable gut microbiota in elderly patients with coronary artery disease (CAD) and evaluate their prognostic significance. Methods A cohort of 200 elderly CAD patients, categorized into mild, moderate, and severe groups according to Gensini scores, together with 50 healthy elderly controls, were enrolled. Levels of specific gut microbial taxa (Bifidobacterium, Enterobacteriaceae, Lactobacillus, Enterococcus, Bacteroides) were quantified using standard anaerobic culture on selective agar media. Serum lipid profiles (TG, TC, HDL-C, LDL-C) were assessed. Correlations among microbial composition, disease severity, and lipid metabolic parameters were analyzed. Patients were followed for 6 months and stratified according to the occurrence of major adverse cardiovascular events (MACE) to assess the association between gut microbiota and clinical outcomes. Multivariable logistic regression was used to adjust for potential confounders. Results Compared with controls, CAD patients exhibited reduced abundances of Bifidobacterium, Lactobacillus, and Bacteroides, along with elevated levels of Enterobacteriaceae and Enterococcus. The magnitude of these changes correlated with CAD severity. These microbial alterations were significantly associated with dyslipidemia and the degree of coronary atherosclerosis. Patients with unfavorable outcomes demonstrated more pronounced alterations in these bacterial groups. After adjusting for potential confounders, the combined microbiota score remained independently associated with poor prognosis (adjusted odds ratio [OR] = 3.484, 95% CI: 2.196–5.527, P < 0.001). Conclusion Elderly CAD patients display distinct alterations in the abundance of selected cultivable gut bacteria, which correlates with both disease severity and lipid metabolic status. Assessment of these bacterial groups may hold potential value for prognostic prediction in this population, but these findings require validation in larger, independent cohorts using more comprehensive sequencing-based methods.