Abstract
Objectives: Ongoing acquisition of antimicrobial resistance genes has made Morganella morganii a new clinical treatment challenge. Understanding the molecular epidemiology of M. morganii will contribute to clinical treatment and prevention.Methods: We undertook a 6-year clinical molecular epidemiological investigation of M. morganii 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.Results: Among all M. morganii isolates (n = 335), forty (11.9%) were recognized as multidrug resistant strains. qnrD1, aac(6′)-Ib-cr, blaTEM–104, and blaCTX–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 blaOXA–181-carrying IncX3 plasmid and a Proteus genomic island 2 variant carrying blaCTX–M–3, aac(6′)-Ib-cr coexisted in the same multidrug resistant strain zy_m28. Additionally, a blaIMP–1-carrying IncP-1β type plasmid was found in the strain nx_m63.Conclusion: This study indicates a clade of M. morganii is prone to acquire resistance genes, and multidrug resistant M. morganii are increasing by harboring a variety of MGEs including two newly discovered ones in the species. We should be vigilant that M. morganii may bring more extensive and challenging antimicrobial resistance issue.
Highlights
Morganella morganii is emerging as a significant opportunistic pathogen in the hospital settings (Liu et al, 2016)
Resistance genes were mainly plasmid mediated and harbored by various transposons or integrons, such as blaKPC-2carrying IncP6 plasmid (Kukla et al, 2018), blaOXA-181-carrying IncN plasmid (McGann et al, 2015), blaNDM-1-carrying IncC plasmid (Aires-de-Sousa et al, 2020), blaNDM-5-carrying IncX3 plasmid (Guo et al, 2019), blaIMP-27-carrying Tn7 transposon (Walkty et al, 2018), blaCTX-M-3-carrying Tn6741 transposon (Luo et al, 2020), cfr-carrying Tn7 transposon (Chen et al, 2019) and blaGES-5-carrying In1390 integron (Moura et al, 2018), which have significantly contributed to the increased levels of resistance in M. morganii
A total of 335 M. morganii clinical isolates were collected from two hospitals in Guangzhou, Southeast China and one hospital in Yinchuan, Northwest China during June 2014 to June 2020
Summary
Morganella morganii is emerging as a significant opportunistic pathogen in the hospital settings (Liu et al, 2016). Morganella morganii has intrinsic resistance to ampicillin, amoxicillin and most of the first- and second-generation cephalosporins because of its intrinsic AmpC resistance gene (Kohlmann et al, 2018). Resistance genes were mainly plasmid mediated and harbored by various transposons or integrons, such as blaKPC-2carrying IncP6 plasmid (Kukla et al, 2018), blaOXA-181-carrying IncN plasmid (McGann et al, 2015), blaNDM-1-carrying IncC plasmid (Aires-de-Sousa et al, 2020), blaNDM-5-carrying IncX3 plasmid (Guo et al, 2019), blaIMP-27-carrying Tn7 transposon (Walkty et al, 2018), blaCTX-M-3-carrying Tn6741 transposon (Luo et al, 2020), cfr-carrying Tn7 transposon (Chen et al, 2019) and blaGES-5-carrying In1390 integron (Moura et al, 2018), which have significantly contributed to the increased levels of resistance in M. morganii
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