Objective To explore the relationship between endoscopic gastric mucosal microorganisms and the occurrence and prognosis of stress ulcer (SUs) in patients with acute ischemic stroke (AIS).

Methods A retrospective analysis was conducted on 125 AIS patients who received intravenous thrombolytic therapy. Gastric antrum mucosal specimens were collected, and the microbial communities were analyzed via 16S rRNA gene sequencing. Helicobacter pylori IgG antibody (HP-IgG) was detected using enzyme-linked immunosorbent assay (ELISA). The occurrence of SUs during hospitalization was recorded, and functional outcomes were evaluated 3 months after AIS onset (a modified Rankin Scale score of 3–6 was defined as a poor outcome).

Results A total of 11 patients (8.8%) developed SUs during hospitalization and were included in the SUs group. Age, NIHSS score at admission, mRS score at admission, and HP-IgG levels in the SUs group were significantly higher than those in the non-SUs group (P ＜ 0.05), but there was no significant difference in gastric microbial α-diversity indices between the two groups (P ＞ 0.05). At the genus level, the abundance of Saccharomonospora in the gastric microbiota of the SUs group was significantly decreased, while the abundances of Peptostreptococcus and Helicobacter were significantly increased (P ＜ 0.01). At 3 months after AIS onset, 26 patients (20.8%) had a poor functional outcome. Age, incidence of SUs, NIHSS score at admission, mRS score at admission, HP-IgG, and the abundances of Peptostreptococcus and Helicobacter in the poor outcome group were significantly higher than those in the good outcome group, whereas the abundance of Saccharomonospora was significantly lower (P ＜ 0.05 to P ＜ 0.01). Correlation analysis showed that HP-IgG level was positively correlated with the abundance of Streptococcus digestive and Helicobacter (all P ＜ 0.05). There was a significant negative correlation between the abundance of Streptococcus digestive and the abundance of Saccharomonospora marina (P ＜ 0.05), and a significant positive correlation between Streptococcus digestive and Helicobacter (P ＜ 0.05). Streptococcus pepticus (OR = 2.112, 95%CI = 1.357 – 3.286) was an independent risk factor of SUs in AIS patients (P ＜ 0.05). HP-IgG (OR = 1.289, 95%CI = 1.074 – 1.547), Glucomonas (OR = 0.125, 95%CI = 0.003 – 0.568), Streptococcus digestus (OR = 9.363, 95%CI = 7.513 – 20.005) and Helicobacter (OR = 3.000, 95%CI = 1.938 – 6.109) were independent risk factors of adverse functional outcome in AIS patients (P ＜ 0.05).

Conclusions The change in the abundance of Peptostreptococcus in AIS patients is associated with the occurrence of SUs, and the changes in HP-IgG levels and the abundances of Saccharomonospora, Peptostreptococcus, and Helicobacter are closely related to the short-term prognosis of these patients.