Abstract:Objective To analyze the distribution and antimicrobial susceptibility of bacterial strains isolated from elderly patients in China, and provide reference for empirical treatment of infection in elderly patients. Methods In 2014-2019,according to technical program of China Antimicrobial Resistance Surveillance System(CARSS), antimicrobial susceptibility testing was performed by Kirby-Bauer method, automatic instrument method or E-test method, data of pathogenic bacteria from elderly patients (≥ 65 years old) were analyzed by WHONET 5.6 software. Results From 2014 to 2019, the ratio of Gram-positive bacteria to Gram-negative bacteria remained at about 1:4 yearly. Among Gram-positive bacteria, Staphylococcus aureus accounted for 5.9%-6.3%, Enterococcus faecium and Enterococcus faecalis accounted for 3.1%-4.0% and 2.8%-2.9% respectively. Isolation rate of methicillin-resistant Staphylococcus aureus (MRSA) decreased year by year, from 48.8% to 35.2%, isolation rate of methicillin-resistant coagulase negative Staphylococcus (MRCNS) accounted for about 80.0% of coagulase negative Staphy-lococcus, vancomycin- and teicoplanin-resistant strains was not found. Resistance rates of Enterococcus faecalis and Enterococcus faecium to vancomycin decreased from 1.1% to 0.3% and 3.7% to 1.4% respectively. Resistance rate of Streptococcus pneumoniae isolated from non-cerebrospinal fluid specimens to cefotaxime decreased year by year, from 10.0% to 6.1%. The top 4 isolated Gram-negative bacteria were Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter baumannii. Resistance rates of Escherichia coli to ceftriaxone and cefotaxime were still higher than 54%, to carbapenems was about 1.3%. Resistance rates of Klebsiella pneumoniae to imipenem and meropenem continued to rise, from 5.6% to 11.7% and 5.2% to 12.1% respectively. Resistance rates of Pseudomonas aeruginosa and Acinetobacter baumannii to carbapenems were about 20% and >56% respectively. Except for ceftazidime, resistance rates of Stenotrophomonas maltophilia to other antimicrobial agents decreased significantly in 2015, and then fluctuated slightly, ranging from 0.9% to 1.4%. Resistance rate of Haemophilus influenzae to ampicillin increased continuously, reaching 63.8% in 2019. Conclusion Gram-negative bacteria are the main pathogens causing infection in the elderly, isolation rates of clinically important antimicrobial-resistant bacteria MRSA and vancomycin-resistant Enterococcus continue to decline, while isolation rate of carbapenem-resistant Klebsiella pneumoniae increased persistently, which needs special attention.