Molecular Characterization of Cephalosporin-Resistant Enteritidis ST11 Isolates Carrying from Children with Diarrhea.

Enteritidis is an important foodborne pathogen with high prevalence of resistance to cephalosporins, imposing a serious threat to public health. Therefore, a total of 162 Enteritidis isolates collected from child patients in China from 2007 to 2017 were characterized for their resistance to cephalosporins and investigated the transmission characteristics of cephalosporin resistance gene. We found that 15 (9.26%) isolates were all resistant to cefalotin (minimum inhibitory concentration [MIC] ≥512 μg/mL), ceftazidime (MIC 16-128 μg/mL), ceftriaxone (MIC 64 to ≥512 μg/mL), ceftiofur (MIC 64-256 μg/mL), and cefotaxime (MIC 64 to ≥512 μg/mL) with the possession of cephalosporin resistance genes ( = 13), ( = 1), and ( = 1). Molecular typing further revealed that these 15 isolates belonged to sequence type ST11 and shared close pulsed-field gel electrophoresis patterns, suggesting the possibility of clonal spread in Enteritidis interspecies. Furthermore, conjugation experiments were successfully performed in 13 of 15 isolates, and was present on conjugative plasmids with sizes ranging from 54.7 to 173.4 kb. Compared with recipient C600, transconjugants conferred elevated MICs for cephalosporins ranging from 2- to 2048-fold. The genetic structure surrounding of gene in transconjugants were ΔIS-- ( = 8) and IS-- ( = 3), respectively. Taken together, on the plasmids might contribute to cephalosporin resistance in Enteritidis, and conjugative transfer of might facilitate the spread of cephalosporin resistance in Enteritidis. Hence, effective mitigation measurements are needed to reduce the threat caused by cephalosporin-resistant Enteritidis to public health.