Co-carrying of KPC-2, NDM-5, CTX-M-3 and CTX-M-65 in three plasmids with serotype O89: H10 Escherichia coli strain belonging to the ST2 clone in China.

Carbapenem-resistant Enterobacteriaceae strains as a new serious threat for the public health have been increasingly reported worldwide. In this study, one multi-resistant Escherichia coli strain ZSH6 which co-carried bla, bla and bla, was isolated from human blood sample. By using plasmid conjugation experiments, ZSH6 was found to harbor three plasmids carrying the bla gene, the bla and bla gene, respectively. Whole-genome sequencing of ZSH6 yielded 122 scaffolds of chromosomal DNA and three circular plasmids including pZSH6-bla (46,319 bp), pZSH6-bla (46,161bp) and pZSH6-bla (184,723). The isolate was classified to Sequence Type 2 and to the O89: H10 serotype. The results of genome analyses revealed that ZSH6 carried three virulence factors (capU, gad and iss) and twenty resistance genes [blabla, bla, bla, bla, floR, tet(A), tet(B), dfrA17, aadA5, sul1, mdf(A), mph(A), erm(B), aph(3')-Ia, aph(3')-Ib, aph(4)-Ia, aph(6)-Id, aac(3)-Iva, aac(3)-IId]. Therefore, the co-existence of such a large number of resistance genes in multiple plasmids making ZSH6 highly resistant to almost all kinds of commonly used antibiotics, and brings a serious challenge for resistance control and clinical treatment of infections caused by this bacterium.