Abstract: OBJECTIVE To investigate the characteristics of health care-associated infections (HAIs) and community-acquired infections (CAIs) caused by major multidrug-resistant organisms (MDROs) among the hospitalized patients of medical institutions so as to provide reference for clinical treatment， prevention and control of the infections. METHODS The clinical data were collected from 9 611 683 patients who were hospitalized in 61 hospitals of Suzhou from Jan. 2020 to Dec. 2025 and were retrospectively analyzed. The subjects were divided into the HAI group and the CAI group according to the source of infections. The sites of MDROs infections， species of pathogens and drug resistance spectrum were observed and compared between the two groups of patients. RESULTS The overall case-time incidence rate of MDROs infection was 0.132% in the HAI group， 0.167% in the CAI group. Carbapenem-resistant Acinetobacter baumannii (CRAB)， methicillin-resistant Staphylococcus aureus (MRSA)， carbapenem-resistant Pseudomonas aeruginosa (CRPA) and carbapenem-resistant Klebsiella pneumoniae (CRKP) were dominant among the pathogens isolated from the two groups of patients; the isolation rates of the above pathogens were higher in the HAI group than in the CAI group(P＜0.05). In the two groups， the lower respiratory tract infections were mainly caused by CRKP， CRPA， CRAB and MRSA; carbapenem-resistant Escherichia coli (CREC)， vancomycin-resistant Enterococcus faecalis (VREfa) and vancomycin-resistant Enterococcus faecium(VREfm) were dominant among the pathogens causing the urinary tract infections. The proportions of all the pathogens causing bloodstream infections and surgical site infections were high in the HAI group; the proportions of the patients who had skin and soft tissue infections with MRSA and the patients who had abdominal and digestive system infections with VREfa and VREfm were high in the CAI group. Most of the strains were isolated from ICU， neurosurgery department and emergency department. The CRKP， CREC， CRAB and VRE were highly drug-resistant， while the CRPA and MRSA strains were highly sensitive to most of the antibiotics. CONCLUSIONS There are certain differences in the epidemiological characteristics of the MDROs infection between the HAI group and the CAI group. It is necessary to coordinate the department to boost the reasonable use of antimicrobial drugs， carry out the active screening of key populations and departments as well as surveillance of related pathogens， and reasonably use antibiotics.