Abstract
PURPOSE: To quantify phase-specific changes in antimicrobial resistance (AMR) of Klebsiella pneumoniae and carbapenem-resistant Klebsiella pneumoniae (CRKP) across the pre-, during, and post-pandemic phases to inform post-pandemic antimicrobial stewardship and infection prevention and control (IPC). PATIENTS AND METHODS: We performed a retrospective study at a tertiary hospital in Southwest China (2018-2024), quantifying AMR and isolate distribution by patient age, sex, specimen type, and clinical department for Klebsiella pneumoniae and CRKP across the pre-, during, and post-pandemic phases. RESULTS: We identified 7073 non-duplicate Klebsiella pneumoniae isolates; CRKP comprised 4.9%. Among patients aged <18 years, the Klebsiella pneumoniae isolation rate declined during the pandemic and rebounded in the post-pandemic phase (P < 0.001), mirroring the trend in blood specimens (P < 0.05). In contrast, isolation rates of Klebsiella pneumoniae and CRKP rose during and post-pandemic among patients aged ≥65 years, in sputum, and in intensive care units (ICUs) and respiratory department (P < 0.05). Resistance to ceftazidime in Klebsiella pneumoniae decreased from 25.3% pre-pandemic to 16.2% during the pandemic and rebounded to 19.9% in the post-pandemic (P < 0.001). Similar decrease-rebound trends were observed for other cephalosporins, β-lactam/β-lactamase inhibitor combinations, carbapenems, monobactams, and aminoglycosides (P < 0.05). Notably, fluoroquinolone resistance rose steadily during the pandemic and post-pandemic phases (P < 0.001). Among CRKP isolates, resistance to fluoroquinolones, aminoglycosides, and monobactams increased from 70.0%, 75.0%, and 90.0% in 2018 to 94.9%, 90.8%, and 96.9% in 2024, respectively. CONCLUSION: Klebsiella pneumoniae resistance temporarily declined during the pandemic but rebounded in the post-pandemic phase, whereas fluoroquinolone resistance continued to rise throughout. In the post-pandemic phase, CRKP exhibited markedly elevated resistance to aminoglycosides, fluoroquinolones, and monobactams, highlighting the urgent need for sustained AMR surveillance, AMS, and targeted IPC in the post-COVID-19 era.