Objective  To understand the composition and drug resistance of pathogens causing nosocomial infection in a grade Ⅲ (A) hospital in Beijing and provide theoretical basis for guiding clinical rational drug use.

  Methods  The drug susceptibility data of pathogens isolated from samples of all patients with nosocomial infection in our hospital from January 1, 2015 to December 31, 2019 were retrospectively collected for the analyses on pathogen distribution, infection sites and antibiotic resistance, as well as the antibiotic use rate and intensity in the hospital in recent years.

  Results  A total of 3522 strains of pathogenic bacteria were isolated. The main gram negative bacteria were Pseudomonas aeruginosa (596 strains, 16.92%), Escherichia coli (353 strains, 10.02%), Klebsiella pneumoniae (285 strains, 8.09%), Acinetobacter baumannii (224 strains, 6.36%), and the gram positive bacterium was Enterococcus faecium (208 strains, 5.91%). The departments with high pathogen isolation numbers were ICU (890 strains, 25.31%), general surgery (582 strains, 16.55%), cadre ward (483 strains, 13.74%), hematology department (263 strains, 7.48%), emergency ward (238 strains, 6.77%). A total of 7324 cases of nosocomial infection occurred. The main infection sites were respiratory tract (3813 cases, 52.06%), urinary system (1015 cases, 13.90%) and digestive tract (740 cases, 10.10%). From 2016 to 2019, the use rate of antibiotics in our hospital decreased from 46.20% to 38.10%. The antibiotic use intensity in our hospital decreased from 34.76 to 31.69. Only the proportion of multidrug resistant K. pneumoniae increased from 24.67% to 36.74%, and the proportions of multidrug resistance of other bacteria decreased in varying degrees.

  Conclusion  The results of this study indicated that the pathogens causing nosocomial infection in our hospital were mainly gram negative bacteria, the main infection site was respiratory tract and the first 3 departments with high pathogen isolation numbers were ICU, general surgery and cadre ward. The antibiotic use rate and intensity all decreased. The distribution, main infection sites and antibiotic resistance of main pathogens causing nosocomial infection changed gradually wit year. The antibiotic resistance of some pathogens increased with year, to which close attention should be paid. It is necessary to strengthen the management in the departments where nosocomial infection is prone to occur.