Background: the co-production of carbapenemases and mcr-genes represents a worrisome event in the treatment of Enterobacteriaceae infections. The aim of the study was to characterize the genomic features of two clinical Enterobacter cloacae complex (ECC) isolates, co-producing VIM and MCR enzymes, in Italy. Methods: species identification and antibiotic susceptibility profiling were performed using MALDI-TOF and broth microdilution methods, respectively. Transferability of the bla(VIM-) and mcr- type genes was verified through conjugation experiment. Extracted DNA was sequenced using long reads sequencing technology on the Sequel I platform (PacBio). Results: the first isolate showed clinical resistance against ertapenem yet was colistin susceptible (EUCAST 2020 breakpoints). The mcr-9.2 gene was harbored on a conjugative IncHI2 plasmid, while the bla(VIM-1) determinant was harbored on a conjugative IncN plasmid. The second isolate, resistant to both carbapenems and colistin, harbored: mcr-9 gene and its two component regulatory genes for increased expression on the chromosome, mcr-4.3 on non-conjugative (yet co-transferable) ColE plasmid, and bla(VIM-1) on a non-conjugative IncA plasmid. Conclusions: to our knowledge, this is the first report of co-production of VIM and MCR in ECC isolates in Italy.

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

Marchetti, Vittoria Mattioni;Migliavacca, Roberta
Supervision
2021-01-01

Abstract

Background: the co-production of carbapenemases and mcr-genes represents a worrisome event in the treatment of Enterobacteriaceae infections. The aim of the study was to characterize the genomic features of two clinical Enterobacter cloacae complex (ECC) isolates, co-producing VIM and MCR enzymes, in Italy. Methods: species identification and antibiotic susceptibility profiling were performed using MALDI-TOF and broth microdilution methods, respectively. Transferability of the bla(VIM-) and mcr- type genes was verified through conjugation experiment. Extracted DNA was sequenced using long reads sequencing technology on the Sequel I platform (PacBio). Results: the first isolate showed clinical resistance against ertapenem yet was colistin susceptible (EUCAST 2020 breakpoints). The mcr-9.2 gene was harbored on a conjugative IncHI2 plasmid, while the bla(VIM-1) determinant was harbored on a conjugative IncN plasmid. The second isolate, resistant to both carbapenems and colistin, harbored: mcr-9 gene and its two component regulatory genes for increased expression on the chromosome, mcr-4.3 on non-conjugative (yet co-transferable) ColE plasmid, and bla(VIM-1) on a non-conjugative IncA plasmid. Conclusions: to our knowledge, this is the first report of co-production of VIM and MCR in ECC isolates in Italy.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11571/1395095
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