Abstract
BACKGROUND: The prevalence of carbapenem-resistant Enterobacteriaceae (CRE) has emerged as a serious public health problem worldwide, and the data on the fecal carriage of CRE strains in hospitalized children remain limited. This study aimed to investigate the molecular characteristics of intestinal colonization of CRE in hospitalized children in Shandong, China. METHODS: A retrospective study was conducted from August to November 2023. Antimicrobial susceptibility testing was performed by the broth microdilution method. Carbapenemase genes, drug resistance genes, and plasmid replicon types were detected using multiplex real-time PCR and whole-genome sequencing. Multilocus sequence typing (MLST) was used to determine the genetic relationships between strains. RESULTS: A total of 20 CRE isolates were identified from 432 fecal samples, with a fecal carriage rate of 4.6%. The CRE isolates predominantly consisted of Escherichia coli (E. coli, n = 13) and Klebsiella strains (n = 6). CRE isolates showed a high resistance rate of 90-100% to seven β-lactam antibiotics. Resistance rates for other antibiotics such as trimethoprim-sulfamethoxazole, tetracycline, azithromycin, ciprofloxacin, chloramphenicol, nalidixic acid, and streptomycin were 90, 85, 85, 80, 75, 75, and 75%, respectively. CRE isolates showed low resistance to amikacin (20%), and none of the isolates were resistant to tigecycline. Additionally, the multidrug resistance rate of CRE isolates was 95%. All CRE strains carried sulfonamide antibiotic and β-lactamase resistance genes, of which the most common β-lactamase resistance genes were bla (NDM-1) (n = 9), bla (NDM-5) (n = 7) and bla (OXA-1) (n = 7). Resistance genes to tetracycline and macrolide antibiotics were also widespread among the strains. The study found that IncFIB and IncFII series plasmids were present in 84 and 42% of the CRE strains, respectively. Additionally, Col, IncFIA, IncC, IncHI2, and IncX series plasmids were also detected. MLST analysis revealed diverse sequence types (STs) among CRE isolates, with ST167 being a common ST among E. coli isolates. CONCLUSION: This study revealed bla (NDM) E. coli were the dominant isolates in fecal samples of hospitalized children in Shandong Province, with a broad multidrug resistance to antibiotics, emphasizing that infection control measures need to be taken to limit the spread of these strains.