Coexistence of blaNDM–5 and tet(X4) in international high-risk Escherichia coli clone ST648 of human origin in China

Abstract

The emergence of pathogens is conferring resistance to last-resort therapies such as tigecycline, colistin, and carbapenems, limiting the therapeutic options, and raising concerns about the emergence of new "superbugs." This study reports the first incident of a <i>bla</i> _NDM-5 and <i>tet</i>(X4) co-harboring <i>Escherichia coli</i> with resistance to carbapenem and tigecycline recovered as the causative agent of a urinary tract infection in a 94-year-old patient. The <i>E. coli</i> strain ECCL209 carries multiple resistance genes [i.e., <i>bla</i> _{TEM-1<i>B</i>} , <i>bla</i> _NDM-5, <i>bla</i> _<i>CMY-</i>2, <i>aadA22, florR, erm</i>(B), <i>mph</i>(A), <i>erm</i>(42), <i>lnuG</i>, <i>qnrS1</i>, and <i>sul</i>2] and exhibits resistance to almost all clinically used antibiotics. MLST analysis found that the strain belongs to ST648, considered a worldwide high-risk pandemic clone. Moreover, multiple plasmid incompatibility types were detected, i.e., IncHI1A, IncHI1B, IncFII, IncFIA, IncFIB, IncQ1, Col, and IncX4. Genetic analysis revealed that <i>bla</i> _NDM-5 and <i>tet</i>(X4) genes were localized on two hybrid plasmids with multiple replicons. Continuous monitoring studies are suggested to quantify the antimicrobial resistance and assess the dissemination of such superbugs into a human healthcare setting.