Clinical Molecular and Genomic Epidemiology of Morganella morganii in China

Abstract

<b>Objectives:</b> Ongoing acquisition of antimicrobial resistance genes has made <i>Morganella morganii</i> a new clinical treatment challenge. Understanding the molecular epidemiology of <i>M. morganii</i> will contribute to clinical treatment and prevention. <b>Methods:</b> We undertook a 6-year clinical molecular epidemiological investigation of <i>M. morganii</i> from three tertiary hospitals in China since 2014. Antimicrobial susceptibility testing was performed using a VITEK-2 system. All isolates were screened for β-lactam and plasmid-mediated quinolone resistance genes by PCR. Isolates carrying carbapenem-resistant genes were subjected to whole-genome sequencing (WGS). The variation and evolution of these mobile genetic elements (MGEs) were then systematically analyzed. <b>Results:</b> Among all <i>M. morganii</i> isolates (<i>n</i> = 335), forty (11.9%) were recognized as multidrug resistant strains. <i>qnrD1</i>, <i>aac(6')-Ib-cr</i>, <i>bla</i> _TEM-104, and <i>bla</i> _CTX-M-162 were the top four most prevalent resistance genes. Notably, phylogenomic and population structure analysis suggested clade 1 (rhierBAPS SC3 and SC5) associated with multiple resistance genes seemed to be widely spread. WGS showed a <i>bla</i> _OXA-181-carrying IncX3 plasmid and a <i>Proteus</i> genomic island 2 variant carrying <i>bla</i> _CTX-M-3, <i>aac(6')-Ib-cr</i> coexisted in the same multidrug resistant strain zy_m28. Additionally, a <i>bla</i> _IMP-1-carrying IncP-1β type plasmid was found in the strain nx_m63. <b>Conclusion:</b> This study indicates a clade of <i>M. morganii</i> is prone to acquire resistance genes, and multidrug resistant <i>M. morganii</i> are increasing by harboring a variety of MGEs including two newly discovered ones in the species. We should be vigilant that <i>M. morganii</i> may bring more extensive and challenging antimicrobial resistance issue.