Elevated Aromatic Microbial Metabolites in Post-Stroke Patients with Pneumonia

Background and Aims

Aromatic microbial metabolites of tyrosine and phenylalanine have been identified as biomarkers associated with disease severity and mortality in critically ill patients with infectious complications [1]. Post-stroke patients are vulnerable to infectious complications, particularly nosocomial pneumonia, due to stroke-induced immunosuppression and CNS depression. Early identification of patients at increased risk for these complications may enable timely preventive strategies.

This study aimed to evaluate the prognostic significance of the sum of three sepsis-associated metabolites (4-hydroxyphenyllactic, 4-hydroxyphenylacetic, and phenyllactic acids) measured in blood serum during the early post-stroke period for predicting infectious complications and in-hospital mortality in post-stroke patients.

Methods

This retrospective observational study included 29 patients (9 men, 20 women; median age 77 years, range 31–88) following ischemic (n=23), intracerebral haemorrhagic (n=1), or subarachnoid haemorrhagic (n=5) stroke. Serum samples were collected during the early post-stroke period (median: day 3; range: 0–15 days after stroke onset). The concentration of aromatic metabolites was measured using gas chromatography-mass spectrometry. The sum of three metabolites (Sum 3) was calculated for each patient. Patients were stratified by the development of pneumonia (15 vs 14) and by in-hospital mortality (10 vs 19).

Results

Patients who developed pneumonia demonstrated significantly higher admission Sum 3 levels compared to patients without pneumonia: 2.7 (2.0–5.3) vs 1.1 (0.9–1.8) µM, p = 0.002; similarly, non-survivors had significantly elevated Sum 3 compared to survivors: 3.8 (2.2–5.4) vs 1.2 (0.9–2.3) µM, p = 0.003 (Mann-Whitney U test). Notably, all 10 deaths (100%) occurred exclusively among patients with pneumonia: 10 vs 0, p < 0.001 (Fisher's exact test).

Conclusions

These results suggest that profiling of phenolic metabolites at admission may serve as a tool for risk stratification in stroke units, enabling targeted prophylactic strategies for high-risk patients.

References

1. https://www.mdpi.com/1420-3049/27/15/4784