Abstract: OBJECTIVE To investigate the clinical and epidemiological characteristics of health care-associated infection (HAI) caused by Raoultella ornithinolytica so as to provide bases for clinical diagnosis and treatment of the infection with this species. METHODS A total of 34 patients with R. ornithinolytica infection who were treated in Ruijin Hospital, Shanghai Jiao Tong University School of Medicine from Sep. 2023 to Aug. 2025 were enrolled in the study, the clinical characteristics of the patients were retrospectively analyzed, and the antimicrobial susceptibility testing for the R. ornithinolytica strains was performed. RESULTS The 34 patients with R. ornithinolytica infection mainly distributed in pancreatic surgery department, intensive care unit (ICU), respiratory medicine department and geriatric department. The average length of hospital stay of the 34 patients was (30.48±31.46)days, the patients with malignant tumors accounted for 44.11%, and the patients with hypertension accounted for 29.41%. Before the species was isolated, 32.35% of the patients were treated with carbapenems antibiotics, 44.11% were treated with no less than 3 types of broad-spectrum antibiotics, and 32.35% were detected with carbapenem-resistant organisms (CROs). The drug resistance rates of the 34 R. ornithinolytica isolates to cefazolin, aztreonam and cefuroxime were 82.36%, 64.71% and 49.90%, respectively; the drug susceptibility rates to fosfomycin, colistin and tetracycline were 97.06%, 94.12% and 94.12%, respectively. CONCLUSIONS The R. ornithinolytica strains are often isolated from the patients who have immunological underlying diseases and were treated with multiple broad-spectrum antibiotics for long period of time, and the strains are highly resistant to the first and second generations of cephalosporins. It is necessary for the hospital to reasonably use antibiotics based on the result of antimicrobial susceptibility testing.