Gut Microbiota Improve the Prediction of Stroke-Associated Pneumonia Risk and Outcomes in Acute Ischemic Stroke.

Stroke-associated pneumonia (SAP) is the most significant acute ischemic stroke (AIS) comorbidity. This investigation aimed to explore the relationship between gut microbiome composition and SAP risk in patients with moderate-to-severe AIS and to develop a robust and accessible SAP risk-prediction model for this population. This prospective study included AIS patients with an NIHSS score ≥ 9 within 48 h of onset who were admitted to the First Affiliated Hospital of Wenzhou Medical University. Rectal swabs and sputum samples were collected for 16S rRNA gene sequencing and analyzed via QIIME to evaluate microbial composition. Blood samples were subjected to untargeted metabolomics analysis via liquid chromatography‒mass spectrometry (LC‒MS). Logistic and Cox regression analyses were conducted (α = 0.05). Fifty of 104 AIS patients (48.1%) developed SAP. Microbiota abundances significantly differed between groups. Logistic regression analysis revealed that Finegoldia protected against SAP (OR 0.710, 95% CI: 0.533 - 0.946, p = 0.019), whereas Lactobacillus (OR 1.347, 95% CI: 1.015 - 1.789, p = 0.039) increased SAP risk. An improved SAP prediction model combining the A²DS² score with seven taxa yielded an AUC of 0.746 (95% CI: 0.650 - 0.841, p < 0.001). Cox regression analysis revealed that genus Clostridium (HR 1.618, 95% CI: 1.241 - 2.110, p < 0.001) was an independent risk factor for mortality, whereas genus Streptococcus (HR 0.751, 95% CI: 0.589 - 0.958, p = 0.021) was a protective factor. Our findings suggest that combining clinical indicators, gut microbiota, and blood metabolites enhances SAP prediction. Furthermore, microorganisms can potentially serve as prognostic markers and therapeutic targets for SAP in the future.