Staphylococcus epidermidis-associated brain abscess following endovascular treatment of a ruptured intracranial aneurysm: potential immune-inflammatory mechanisms—a case report and literature review

Background Endovascular treatment(EVT) is a key therapeutic approach for ruptured intracranial Aneurysms; however, postoperative brain abscesses are extremely rare, and their pathogenesis and optimal treatment strategies remain unclear. This article reports a case of a Staphylococcus epidermidis -associated brain abscess that developed following stent-assisted coil embolization for subarachnoid hemorrhage caused by a ruptured anterior communicating artery aneurysm and discusses the underlying immune and inflammatory mechanisms as well as treatment strategies. Case presentation A 49-year-old man underwent stent-assisted coil embolization for subarachnoid Hemorrhage(SAH) from a ruptured anterior communicating artery aneurysm. Recovered well from operation and discharged. He, however, presented on the 34th postoperative day with a high-grade fever, headache, nausea, and vomiting. Brain imaging showed a brain abscess in the left frontal lobe, approximately 42 mm × 27 mm. However, there were no clear signs of severe neurological deterioration or a critical phase of cerebral herniation. Laboratory tests revealed high white blood cell and neutrophil counts, low lymphocyte counts, and variable reductions in CD3+, CD4+, and CD8+ T cells, CD19+ and CD20+ B cells, and Natural Killer cells(NK cells). Meanwhile, IL-1β, IL-6, TNF- α, and IL-10 levels increased, indicating deep immunological and inflammatory changes during infection. Inflammatory and immune markers improved slightly after antimicrobial therapy, but clinical symptoms persisted, and robot-assisted stereotactic abscess drainage was performed. A culture of pus grew methicillin-resistant Staphylococcus epidermidis (MRSE). Whole-genome sequencing confirmed the species and ST2 subtype and genetic features associated with β-lactam resistance. Initially, based on the consultation findings, meropenem and metronidazole were empirically administered as broad-spectrum antibiotics; after MRSE was confirmed, treatment was switched to vancomycin, and the patient’s clinical symptoms and laboratory parameters gradually improved. Postoperative imaging showed no recurrence of abscess, and the patient was in satisfactory general condition and no aftereffects whatsoever at six months’ follow-up. Conclusion We present a case report of an isolated brain abscess due to Staphylococcus epidermidis that developed after EVT of a ruptured intracranial aneurysm, which is a novel and clinically rare case. It also provides new clinical evidence for understanding this type of rare complication and optimizing treatment strategies.