Intracranial infection is one of the common clinical complications after neurosurgery, especially after external cerebrospinal fluid drainage. Postoperative intracranial infection has a very high incidence, and its incidence is about 0.34%-3.1%. Once infection occurs, it will directly affect the length of hospitalization, mortality and disability of postoperative patients. The pathogenic bacteria of postoperative intracranial infections include G-bacteria and G+ bacteria, and fungi. Common G+ bacteria are Staphylococcus aureus. Common G-bacteria are Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa Bacteria, Escherichia coli and so on. In recent years, studies have reported that postoperative intracranial infections of G-bacteria are gradually increasing. In the previous study of our research group, it was found that Acinetobacter baumannii and Klebsiella pneumoniae accounted for the top two pathogens of postoperative intracranial infections in ICU. In particular, the proportion of carbapenem-resistant G-bacteria has increased, which brings difficulty and challenge to the treatment and seriously affects the prognosis of patients. Different pathogen infections may lead to different prognosis of patients with intracranial infection after neurosurgery. With different pathogens as the starting point, there are few studies comparing the clinical features, risk factors, and prognosis of intracranial infections after neurosurgery. Therefore, it is great significant to explore and understand different pathogenic bacteria, risk factors, drug resistance, treatment options, and prognosis after neurosurgery.

1. To study the epidemiological distribution of pathogenic bacteria of intracranial infection after neurosurgery.
2. To study the risk factors of intracranial infection after neurosurgery (operations, type of external drainage tube, days of drainage tube , etc.).
3. To compare differences in clinical character，risks , treatment options, prognostic indicators between G+ bacterial infection group and G-infected bacterial group after neurosurgery.

Inclusion Criteria:

- Patients diagnosed with intracranial infection after surgery and positive pathogenic microorganisms cultured in cerebrospinal fluid

Exclusion Criteria:

• (1) < 18 years old, (2) Pregnant or lactating women, (3) fungus in CSF culture, (4) Clinical judgment is not intracranial infection, and CSF culture positive considers contaminating patients.

A retrospective review of the Second Affiliated Hospital of Zhejiang University from January 2013 to May 2021, diagnosed patients with intracranial infection after surgery and positive for pathogenic microorganisms cultured in cerebrospinal fluid.