The molecular and epidemiological characteristics of carbapenemase-producing Enterobacteriaceae isolated from children in Shanghai, China, 2016-2021.

Background: We isolated the carbapenemase-producing Enterobacteriaceae (CPE) strains from children during 2016-2021 in Shanghai, China and investigated the antimicrobial resistance, molecular and epidemiological features of these isolates.

Methods: Antimicrobial susceptibility tests were performed to confirm the carbapenem resistance. Carbapenemase production was assessed by the rapid phenotypic identification of five major carbapenemases (KPC, NDM, VIM, IMP, and OXA-48), which were further confirmed by PCR amplification and sequencing. Multilocus sequence typing (MLST) was conducted for phylogenetic analyses.

Results: A total of 320 CPE strains were collected from 2016 to 2021, consisting of carbapenemase-producing Klebsiella pneumoniae (CP-Kpn, 55.0%), Escherichia coli (CP-Eco, 24.5%) and Enterobacter cloacae (CP-Ecl, 20.4%) and others (2, 0.1%). NDM was the primary carbapenemase (67.6%) in children, followed by KPC(26.4%), IMP(5.3%) and OXA-48 (0.6%). The minimum inhibitory concentration (MIC) for imipenem has been increasing from 2016 to 2021. NDM and KPC isolates are high resistant while IMP strains show the lower resistant to imipenem. Invasive infection accounted for 10.7% of CPE-related infections and was mainly caused by CP-Kpn (70.6%). NDM-Kpn was detected in 51.8% of infants (70.8% of neonates), while KPC-Kpn was mainly isolated from non-infants (56.3%∼64.3%). ST11 was the primary clone (64.6%) of KPC-Kpn and presented an increasing trend from 2016 to 2021.

Conclusion: NDM is widely prevalent and transfers among CPE strains in children. NDM-Kpn shows the most serious threat to infants, especially to neonates. High-risk clone of ST11 KPC-Kpn should be paid more attention and monitored continuously in children.