Epidemiological investigation and patterns of antimicrobial use in multidrug-resistant bacteria at a tertiary hospital: a retrospective cohort study.

OBJECTIVE: To analyse trends and characteristics of multidrug-resistant (MDR) bacteria over the past 7 years, in relation to patterns of antimicrobial use, to inform rational antimicrobial use and strengthen hospital infection control measures. DESIGN: Retrospective cohort study. SETTING: A large teaching hospital in Tianjin, a major metropolitan city in northern China. PARTICIPANTS: A total of 190 352 inpatients aged >18 years, admitted between 1 January 2017 and 31 December 2023, were included. Patients were eligible if they had complete clinical data and met the five quality control indicators for multidrug-resistant bacteria (QC-MRB), defined in the 'Hospital Infection Surveillance Specifications' (WS/T 312-2023). Patients with MDR infections before admission or those with duplicate results from multiple specimens were excluded. RESULTS: Statistical analysis revealed a detection rate of 12.11% for the five QC-MRB and an incidence rate of 0.20%. The findings also indicated an upward trend in the detection and incidence rates of carbapenem-resistant Enterobacteriaceae, despite a relatively stable rate of antimicrobial use over 7 years. A positive correlation was observed between the incidence of MDR bacteria and the intensity of antimicrobial use within the hospital setting. CONCLUSIONS: The hospital's bacterial data align with national trends. It established an interdisciplinary management framework for clinical data analysis and prediction of antimicrobial resistance. This approach enhances infection control measures and supports the rational use of antimicrobials.