Objective:To investigate the level and significance of CD64 index, matrix metalloproteinase-9 (MMP-9) and serum amyloid A (SAA) in peripheral blood of patients with severe carbapenem resistant Enterobacteriaceae (CRE) infection.Methods:A total of 61 patients with severe CRE infection who were admitted to the neurosurgery department of Kashgar First People′s Hospital from January 2019 to January 2022 were selected as the CRE group, and 100 patients with severe carbapenem sensitive Enterobacteriaceae (CSE) infection were selected as the CSE group. The difference in clinical data between the two groups was compared, and the difference in clinical data between the dead and surviving patients in the CRE group was compared. The value of CD64 index, MMP-9 and SAA in differential diagnosis of CRE was analyzed. Logistic regression was used to analyze the influencing factors of prognosis in patients with CRE infection.Results:The age, hypertension, lung disease, liver and kidney disease, comorbidities≥2, antibiotic use≥2 combinations, antibiotic use time>10 days, proportion of carbapenem use, CD64 index, MMP-9, and SAA of the CRE group patients were significantly higher than those of the CSE group patients (all P<0.05). The area under the receiver operating characteristic (ROC) curve for CD64 index, MMP-9, and SAA differential diagnosis of CRE was 0.857, 0.701, and 0.655, respectively (all P<0.05). In the CRE group, the age , the score of Acute Physiological and Chronic Health Status Ⅱ (APACHE Ⅱ) score at admission, diabetes, liver and kidney diseases, comorbidities≥2, the proportion of carbapenems, CD64 index, MMP-9 and SAA of dead patients were significantly higher than those of survivors (all P<0.05). Logistic regression analysis showed that age, APACHE Ⅱ score at admission, comorbidities≥2, CD64 index, MMP-9, and SAA were influencing factors for the prognosis of severe CRE patients (all P<0.05). Conclusions:The peripheral blood CD64 index, MMP-9, and SAA have certain application value in the diagnosis of neurological severe CRE infection, and are also influencing factors for the prognosis of CRE infected patients.