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Genomic Characterization of VIM and MCR Co-Producers: The First Two Clinical Cases, in Italy

Vittoria Mattioni Marchetti1,2, Ibrahim Bitar1,2, Mario Sarti3

  • 1Department of Microbiology, Faculty of Medicine and University Hospital in Pilsen, Charles University, 306 05 Pilsen, Czech Republic.

Diagnostics (Basel, Switzerland)
|January 9, 2021
PubMed
Abstract

Insights

Two Italian Enterobacter cloacae complex isolates co-produced VIM carbapenemases and MCR-type genes, raising concerns for treating Enterobacteriaceae infections. This study details their genomic features and resistance mechanisms.

Area of Science:

  • Medical Microbiology
  • Genomics
  • Antimicrobial Resistance

Background:

  • Co-production of carbapenemases and MCR-type genes is a significant threat in treating Enterobacteriaceae infections.
  • Enterobacter cloacae complex (ECC) isolates are increasingly recognized for harboring antimicrobial resistance genes.

Purpose of the Study:

  • To characterize the genomic features of two Italian clinical ECC isolates co-producing VIM and MCR enzymes.
  • To investigate the genetic basis of resistance to carbapenems and colistin in these isolates.

Main Methods:

  • Species identification and antibiotic susceptibility profiling using MALDI-TOF and broth microdilution.
  • Verification of gene transferability via conjugation experiments.
  • Whole-genome sequencing using long-read PacBio Sequel I technology.

Main Results:

  • One isolate harbored mcr-9.2 on an IncHI2 plasmid and blaVIM-1 on an IncN plasmid, showing ertapenem resistance but colistin susceptibility.
  • The second isolate exhibited resistance to both carbapenems and colistin, with mcr-9 on the chromosome and mcr-4.3 on a ColE plasmid, alongside blaVIM-1 on an IncA plasmid.
  • Both isolates demonstrated complex plasmid-mediated and chromosomal resistance mechanisms.

Conclusions:

  • This is the first report of VIM and MCR co-production in Enterobacter cloacae complex isolates in Italy.
  • The findings highlight the emergence of multidrug-resistant ECC strains with significant public health implications.
Keywords:
Enterobacter cloacae complexblaVIM-1colistin resistancemcr-4.3mcr-9

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