Molecular epidemiological characteristics of carbapenem-resistant Enterobacteriaceae strains from a teaching hospital

OBJECTIVE To explore the clinical distribution, drug resistance phenotypes, genotypes and homology of the carbapenem-resistant Enterobacteriaceae (CRE) strains isolated from a teaching hospital so as to provide guidance for prevention and treatment of drug-resistant strains. METHODS Totally 216 clinical CRE isolates were collected from The Affiliated Hospital of Qingdao University from Dec. 2019 to Jan. 2024. The identification, drug susceptibility testing, carbapenemase test and next general sequencing were performed for the strains. The clinical distribution, drug resistance rates and homology of the strains were statistically analyzed. RESULTS Among the 216 strains of CRE, Escherichia coli (90 strains), Klebsiella pneumoniae (66 strains) and Enterobacter hormaechei (29 strains) were dominant. The E. coli strains mainly carried bla_NDM-5 gene, with totally 39 ST types involved; ST167, ST410 and ST617 ranked the top 3. Among the E. coli strains, 1 strain carried bla_IMP-8 and bla_NDM-5 genes at the same time. The K. pneumoniae strains mainly carried bla_KPC-2 gene, and ST11 was the predominant type. 1 of the K. pneumoniae strains carried a novel bla_KPC gene named as bla_KPC-223. A strain of K. pneumoniae that carried bla_NDM-46 gene was obtained in the study. The E. hormaechei strains mainly carried bla_NDM-1 gene, and ST171 was the predominant type. CONCLUSIONS E. coli, K. pneumoniae and E. hormaechei are dominant among the CRE strains isolated from the hospital. There are a variety of multilocus sequencing types of the strains. A novel bla_KPC-223 gene is discovered in the K. pneumoniae strain. Databases retrieval indicates that it is for the first time to report the K. pneumoniae strain carrying bla_NDM-46 gene and the E. coli strain carrying bla_IMP-8 and bla_NDM-5 genes at the first time.