In this study, we collected 5442 strains of Klebsiella pneumoniae from the First Affiliated Hospital of Hebei North University of China from January 1, 2014 to June 30, 2022. After removing 895 duplicate strains from the same patient, the remaining 4547 strains of KP (4547 patients) were used for research and analysis. Blood (8–10 mL), cerebrospinal fluid (1 mL), pleural fluid (1 mL), and aspirate (1 mL) were cultured in a liquid medium (Becton Dickinson and Company/FX-200, MD, USA). Urine (1 μL) and other clinical samples were streaked onto Columbia blood and MacConkey agar plates (Jinan Baibo Biological) and incubated for 24 h at 35 °C. Species identification and determination of antimicrobial susceptibility were performed using the BD-Phoenix 100 system (Becton, Dickinson and Company, New Jersey, USA).
Susceptibility experiments were performed using the micro broth dilution method, and prior to testing, the strains were prepared as bacterial suspensions at a concentration of 0.5, McFarland standard. Following this, 25 μL of the bacterial suspension and 45 μL of the indicator were added to the broth and mixed thoroughly within 15 min of preparation of the bacterial suspension. The remaining bacterial suspension was added to the raw chemical well reaction area, the solution in the broth tube was added to the drug sensitivity reaction area, sealed with a cap, placed into the BD automatic drug sensitivity identification instrument, and incubated at 35 °C for 24 h.
CLSI - M100 ED30 breakpoints were used for the determination of drug sensitivity. An MIC ≥4 mg/L of imipenem or meropenem against KP was defined as CRKP, and an MIC ≥2 mg/L of ceftazidime, ceftriaxone, cefotaxime, or aztreonam against KP was defined as extended-spectrum β-lactamase- KP (ESBL-KP). KP QC strain ATCC700603 and Escherichia coli QC strain ATCC25922 were used.Supplementary Table 1
Susceptibility experiments were performed using the micro broth dilution method, and prior to testing, the strains were prepared as bacterial suspensions at a concentration of 0.5, McFarland standard. Following this, 25 μL of the bacterial suspension and 45 μL of the indicator were added to the broth and mixed thoroughly within 15 min of preparation of the bacterial suspension. The remaining bacterial suspension was added to the raw chemical well reaction area, the solution in the broth tube was added to the drug sensitivity reaction area, sealed with a cap, placed into the BD automatic drug sensitivity identification instrument, and incubated at 35 °C for 24 h.
CLSI - M100 ED30 breakpoints were used for the determination of drug sensitivity. An MIC ≥4 mg/L of imipenem or meropenem against KP was defined as CRKP, and an MIC ≥2 mg/L of ceftazidime, ceftriaxone, cefotaxime, or aztreonam against KP was defined as extended-spectrum β-lactamase- KP (ESBL-KP). KP QC strain ATCC700603 and Escherichia coli QC strain ATCC25922 were used.
