Hang Jin,1,2,* Zhongqiang Yan,3,* Xin Ge,4,* Qi Wang,2 Hui Wang,2 Xinying Du,2 Hongbo Liu,2 Chaojie Yang,2 Ying Xiang,2 Sai Tian,2 Shaofu Qiu,1,2 Yu Zhou5 

1School of Public Health, Zhengzhou University, Zhengzhou, People’s Republic of China; 2Department of Infectious Disease Control and Prevention, Center for Disease Control and Prevention of Chinese PLA, Beijing, People’s Republic of China; 3Department of Disease Prevention and Control, The Second Medical Center of PLA General Hospital, Beijing, People’s Republic of China; 4School of Public Health, Anhui Medical University, Hefei, People’s Republic of China; 5Department of Clinical Laboratory, National Clinical Research Center for Geriatric Diseases, The Second Medical Center of Chinese PLA General Hospital, Beijing, People’s Republic of China

*These authors contributed equally to this work

Correspondence: Shaofu Qiu, Center for Disease Control and Prevention of Chinese PLA, Beijing, People’s Republic of China, Email qiushf0613@hotmail.com Yu Zhou, Department of Clinical Laboratory, National Clinical Research Center for Geriatric Diseases, The Second Medical Center of Chinese PLA General Hospital, Beijing, People’s Republic of China, Email zhouy427@163.com

Purpose: This study conducted an phenotypic and whole-genome sequencing analysis with Klebsiella aerogenes to elucidate its clinical epidemiological characteristics, antimicrobial resistance (AMR) phenotype, biofilm formation ability and hemolytic activity testing, AMR genes and phylogenetic relationships, so as to provide a further understanding of the intra-hospital strain transmission.
Methods: Samples were collected from a hospital in Beijing between 2020 and 2022. All strains underwent bacterial identification, antimicrobial susceptibility testing (AST) using the VITEK-2 compact system. Biofilm formation ability and hemolytic activity were tested. Second-generation sequencing was applied to all strains, with those carrying the blaKPC gene were selected for third-generation sequencing. Whole-genome analysis identified resistance genes, plasmid types, MLST typing, and phylogenetic relationships. Plasmids were assembled to detect plasmid structures and AMR gene location.
Results: Among the 42 K. aerogenes isolates, 21 were carbapenem-resistant K. aerogenes (CRKA). All strains exhibited strong biofilm formation and no hemolytic activity. Most were sourced from sputum (83.3%). CRKA demonstrated extensive resistance to antibiotics, particularly β-lactamase inhibitors and Cefotetan. This resistance pattern was closely associated with the presence of an IncFII(pHN7A8) plasmid, which carried multiple resistance genes, including blaKPC-2, blaCTX-M-65, blaTEM-1, rmtB and a large number of mobile elements. The majority of CRKA strains clustered within the same branch of the phylogenetic tree, exhibiting minimal single nucleotide polymorphism (0– 13 SNPs) differences, and they shared the same sequence type (ST292), resistance genes, and plasmids, originating from different departments, suggesting clonal transmission among the hospital.
Conclusion: Our research reveals that the clonal transmission of CRKA occurs across various departments within the hospital. The widespread resistance observed in CRKA, attributed to the presence of blaKPC and ESBLs genes, underscores the need for heightened vigilance to prevent the further dissemination of CRKA within the hospital and, potentially, throughout the wider community.

Keywords: Klebsiella aerogenes, carbapenem resistance, blaKPC-2, clonal transmission