A retrospective analysis of pathogen distribution and antimicrobial resistance trends of bacteria in a tertiary hospital in China, 2021-2025.

BACKGROUND

Antimicrobial resistance (AMR) poses a significant global health threat, with multidrug-resistant organisms (MDROs) increasingly contributing to healthcare-associated infections (HAIs). Understanding local pathogen distribution and resistance trends is essential for guiding empirical therapy and infection control strategies. This study aims to analyze the pathogen distribution and AMR trends of bacteria in a tertiary hospital in South China from 2021 to 2025.

METHODS

A retrospective analysis was conducted on bacterial isolates collected from a tertiary hospital in Guangzhou, China, from 2021 to 2025. Bacterial identification and antimicrobial susceptibility testing were performed using the VITEK 2 automated system and the Kirby-Bauer disk diffusion method, with results interpreted according to CLSI guidelines. Annual data analysis was conducted using WHONET 5.6 software. Antimicrobial consumption was expressed as defined daily doses (DDD) per 1,000 patient-days, and incidence of HAIs caused by MDROs was calculated as cases per 1,000 patient-days.

RESULTS

A total of 25,326 non-duplicate bacterial isolates were analyzed. Gram-negative bacteria predominated throughout the study period, with Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii being the most frequently isolated species. Among Gram-positive bacteria, Staphylococcus aureus showed a marked increase from 2023 onward. Escherichia coli exhibited persistently high resistance to fluoroquinolones (>57%) and third-generation cephalosporins (>50%), with an increasing trend in carbapenem resistance. Klebsiella pneumoniae demonstrated declining resistance to carbapenems but a concerning emergence of tigecycline resistance in 2025 (6.2%). Acinetobacter baumannii maintained high carbapenem resistance (>60%) throughout, with colistin and tigecycline remaining the only consistently effective agents (resistance ≤1.9% and ≤1.8%, respectively). Antimicrobial consumption showed a sustained increase in carbapenem use (from 21.78 to 47.06 DDD per 1,000 patient-days), while incidence of HAIs caused by MDROs declined from 0.30 to 0.12 cases per 1,000 patient-days following intensified infection prevention and control measures implemented in 2024.

CONCLUSIONS

This study reveals a persistently high burden of MDROs in a South China tertiary hospital, particularly among Gram-negative pathogens. Despite increasing antimicrobial consumption, enhanced IPC measures, including active surveillance and improved contact isolation compliance, effectively reduced HAIs-MDROs incidence. These findings underscore the critical importance of integrated antimicrobial stewardship and infection control strategies in combating AMR.