Clinical and resistance characterization of carbapenem-resistant Klebsiella pneumoniae isolated from intensive care units in China

Background: Carbapenem-resistant Klebsiella pneumoniae (CRKP) is a serious threat to health, and the detection rate in intensive care units (ICUs) is relatively high. We compared regional differences in the clinical and molecular characteristics of CRKP from three ICUs in different hospitals, to make a reference and contribution for infection control and clinical medication. Methods: A total of 150 CRKP strains from Chongqing, Beijing, and Nantong, as well as the clinical data of the infected patients, were collected between 2019 and 2021. The carbapenemase phenotype was determined by CarbaNP test, and the outer membrane porin (OMP) genes (ompK35/ompK36), multi-locus sequence typing (MLST) and resistance genes were identified by polymerase chain reaction (PCR) amplification and sequencing. Results: Patients infected with CRKP were mainly elderly, with comorbidity, and had undergone invasive operation and multiple antibiotic therapy. All strains exhibited high-level resistance to most antibiotics except for polymyxin B and tigecycline. Among the CRKP strains, 100 had the blaKPC-2 gene and 8 had bla(NDM-1) gene, which were distributed in all of the hospitals. Nearly all the strains harbored extended-spectrum beta-lactamase (ESBL) genes (bla(SHV), bla(CTX-M), and bla(TEM)). Class C carbapenemase genes (bla(CIT), bla(DHA)), and deletion and mutation of ompK35/ompK36 existed in some strains. ST11 was the main MLST type, followed by ST15. Conclusions: There were a few significant differences in the molecular epidemiology and clinical characteristics, but generally the features of CRKP from the three ICUs aligned fairly well, which might have resulted from dissemination through frequent personnel exchanges between regions.