A gut microbiome score based on three genera provides significant independent and incremental predictive value for SAP over the A2DS2 score, enabling more precise early risk stratification after stroke.
SAP cases exhibited reduced alpha-diversity and distinct beta-diversity compared to controls.
SAP cases had higher levels of Enterococcus and Streptococcus and lower levels of Faecalibacterium compared to controls.
The gut microbiome M-score was independently associated with stroke-associated pneumonia.
Adding the M-score to the clinical A2DS2 score significantly improved predictive performance for SAP.
A nested case-control design was used within a prospective cohort of 551 acute ischemic stroke patients to identify 63 SAP cases.
This research suggests that the composition of gut bacteria in the days immediately following a stroke can help predict which patients will develop pneumonia — a serious and common complication called stroke-associated pneumonia (SAP). The researchers collected stool samples from 551 stroke patients within 24–72 hours of hospital admission and compared the gut bacteria of 63 patients who developed pneumonia to 126 matched patients who did not. They found that pneumonia patients had less diversity in their gut bacteria overall, with notably higher levels of Enterococcus and Streptococcus (bacteria often associated with infection) and lower levels of Faecalibacterium (a bacterium generally associated with gut health). Using these three bacterial markers, the researchers built a simplified 'M-score' that could be added to an existing clinical prediction tool called the A2DS2 score. When the M-score was combined with the A2DS2 score, the ability to correctly identify patients at risk of pneumonia improved meaningfully — the area under the prediction curve rose from 0.76 to 0.84, and risk reclassification also improved significantly. This suggests that gut bacteria information adds value beyond what doctors can already assess from clinical characteristics alone. This research suggests that monitoring gut microbiome changes shortly after a stroke could provide an additional layer of information for identifying high-risk patients earlier, potentially allowing for more targeted preventive care. The findings support the concept of a 'brain-gut-lung axis,' where disruption of gut bacteria after stroke may be linked to lung complications, though further research in larger and more diverse populations would be needed before such testing could be considered for routine clinical use.
Zhang Y, Dong Q, Li W. (2026). Incremental value of a gut microbiome score (M-score) for predicting stroke-associated pneumonia beyond the clinical A2DS2 score: A nested case-control study.. Acta microbiologica et immunologica Hungarica. https://doi.org/10.1556/030.2026.02907