Fecal carriage and molecular epidemiology of carbapenem-resistant Enterobacteriaceae from outpatient children in Shanghai

BACKGROUND: Fecal colonization with carbapenem-resistant Enterobacteriaceae (CRE) is a risk factor for bacterial translocation resulting in subsequent endogenous infections. The purpose of this study is to investigate the prevalence of CRE strains colonization in stool samples of outpatient in a tertiary pediatric hospital of Shanghai, China. METHODS: In a retrospective study, fecal samples were consecutively obtained from patients in 2016 and screening test for CRE was conducted by using home-made MacConkey agar. Antimicrobial susceptibility was determined by the broth microdilution method and β-lactamases were characterized by polymerase chain reaction (PCR) assays and DNA sequencing. Multilocus sequence typing (MLST) was performed for the genetic relationships of the isolates. RESULTS: A total of 880 fecal samples were included for this screening test and 32 CRE strains were identified in 32 non-duplicate fecal samples from 32 children (1.3 ± 1.5 years), with a carriage rate of 3.6%. These strains mainly distributed in Klebsiella pnuemoniae (37.5%) and Escherichia coli (37.5%). All CRE strains showed high resistance to most of the routinely used antibiotics (> 90%) except for polymyxin B and tigecycline. The bla(NDM) gene was the major carbapenemase gene harbored by gastrointestinal CRE strains, followed by bla(KPC-2), bla(IMP-26), and bla(IMP-4). Other β-Lactamase genes including bla(CTX-M), bla(SHV), bla(TEM-1), and bla(DHA-1) were also detected. MLST analysis revealed that various sequence types (STs) were detected in these strains, with ST11 and ST37 being more prevalent in K.pneumoniae and ST101 in E.coli. CONCLUSIONS: This study revealed the prevalence of CRE fecal carriage in children from outpatient and urgent implementation of infection control measure should be conducted to limit the spread of CRE strains.