The Evolving Triad of Carbapenem Resistance: Emergence of Dominant CRPA, Persistent CRAB, and Rebounding CRKP in a Chinese Regional Hospital (2020-2024)

Purpose: Carbapenem-resistant Gram-negative bacteria (CR-GNB) represent a critical threat in healthcare settings. However, their evolving epidemiology in regional hospitals remains poorly understood. We aimed to delineate the resistance trends and risk factors of CR-GNB in a Chinese regional hospital to guide infection control. Patients and Methods: We conducted a retrospective epidemiological study from 2020 to 2024. A total of 148,622 clinical specimens were collected, yielding 19,264 culture-positive isolates. We examined microbial distribution and carbapenem resistance (CR) rates. Multivariable logistic regression was used to identify independent risk factors for CR-GNB infection. Results: The overall culture positivity rate was 12.96%. Gram-negative bacilli accounted for 71.7% of the positive isolates. CR analysis revealed a critical shift: Pseudomonas aeruginosa (CRPA) showed a rapid upward trend (25.3% to 39.3%), Acinetobacter baumannii (CRAB) maintained persistently high resistance (> 86%), and Klebsiella pneumoniae (CRKP) exhibited a rebounding pattern (36.2% in 2024). Multivariable analysis identified male sex, advanced age (> 60 years), and ICU/SICU admission as significant risk factors. In high-burden wards, CRAB and CRKP exhibited extreme resistance (> 96%) to multiple first-line agents. Conclusion: Our findings reveal a critical shift in the CR-GNB landscape, characterized by the emergence of dominant CRPA alongside persistent CRAB and rebounding CRKP. This “Evolving Triad”, entrenched in ICUs, underscores the urgent need for “Proactive Ecological Intervention” strategies. This study provides a crucial epidemiological baseline for regional hospitals. Keywords: carbapenem resistance, gram-negative bacteria, epidemiology, intensive care unit, risk factors