Mobile genetic elements contributing to horizontal gene transfer of blaNDM among Escherichia coli in the community setting.

OBJECTIVE

To investigate the distribution of carbapenem-resistant Enterobacterales (CRE) in the community and to describe the genomic characteristics.

METHODS

CRE screened from fecal samples in healthy people at the health examination center of a tertiary hospital in China underwent Whole genome sequencing (WGS) to analyze genotypic characteristics of CRE. The flanking DNA sequence of blaNDM-5 and mcr1.1 genes were analyzed by Gcluster software.

RESULTS

A total of 7187 fecal samples were screened, and CRE carriage was detected in 0.4 % of the sampled population. In total, 30 Escherichia coli, one Citrobacter freundii and one Klebsiella aerogene were screened. The 30 carbapenem-resistant Escherichia coli (CREC) isolates displayed slight resistance to amikacin (13.3 %) and aztreonam (20.0 %). All the CRE isolates contained blaNDM, and blaNDM-5 (84.4 %) was the most common one. B1 (n = 11) and A (n = 7) were predominant phylogroups. Furthermore, 34 distinct plasmid replicons, 67 different VFs, 22 distinct STs, 17 different FimH types, 26 O:H serotypes as well as 74 MGEs including 61 insertion sequences and 13 transposons were identified. The flanking DNA sequence analysis of blaNDM-5 and mcr1.1 genes indicates the key role of horizontal transfer of blaNDM-5 in the CRE development evidenced by diverse STs and phylogenetic tree.

CONCLUSION

E. coli was the most predominant CRE isolates in community setting, and blaNDM (blaNDM-5) was the main CHβL encoding genes. The high prevalence of ARGs was associated with high resistance to commonly used antimicrobials. Besides, the genetic diversity of these isolates suggested the key role of blaNDM horizontal transfer in the CRE development. Thus, active screening of blaNDM in communities is particularly important for the prevention and control of CRE.