Carbapenem-resistant Morganella morganii carrying blaKPC-2 or blaNDM-1 in the clinic: one-decade genomic epidemiology analysis.

Abstract

Carbapenem-resistant Morganella morganii (CRMM) isolates, particularly those producing Klebsiella pneumoniae carbapenemase-2 (KPC-2) or New Delhi metallo-β-lactamase-1 (NDM-1), are increasingly being recognized as causative agents of nosocomial infections. However, systematic phylogeography and genetic characterization of these isolates worldwide are still lacking. Here, through seven years of surveillance of CRMM in a tertiary hospital, we analyzed the genomic characteristics of bla_KPC-2- or bla_NDM-1-positive CRMM isolates. Furthermore, we conducted a global genomic epidemiological study of Morganella spp. harboring bla_KPC or bla_NDM using the NCBI database over the past decade. By combining the timeline of isolate collection with the structural analysis of the plasmids, we traced the evolution of the IncL/M plasmid, which acquired the bla_KPC-2 gene. Our findings indicate that horizontal transfer of Tn6296 based on IS26 is crucial for the transmission of bla_KPC in CRMM isolates. Additionally, the Tn125 transposon appears to have played an important role in early plasmid-mediated dissemination of bla_NDM; however, it has been surpassed in recent years by other elements, including IS26 and ISCR. In summary, through phylogeographic analysis of Morganella spp. globally, we elucidated their spatial-temporal distribution and revealed the evolutionary characteristics of KPC- or NDM-producing CRMM isolates as the predominant "epidemic" clone.

Importance: Currently, infections attributable to carbapenem-resistant Morganella morganii (CRMM) isolates harboring bla_KPC or bla_NDM are on the rise, highlighting the increasing severity of acquired antimicrobial resistance. However, systematic phylogeographic and genetic characterization of these isolates worldwide is still lacking. In this study, we elucidated the spatial-temporal distribution and evolutionary trajectory of bla_KPC and bla_NDM genes within their core genetic environments. We emphasize the necessity of strengthening surveillance and controlling these organisms in clinical settings to prevent the generation of so-called "superbug" isolates.