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

BACKGROUND

the co-production of carbapenemases and -genes represents a worrisome event in the treatment of infections. The aim of the study was to characterize the genomic features of two clinical 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 and - 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 gene was harbored on a conjugative IncHI2 plasmid, while the determinant was harbored on a conjugative IncN plasmid. The second isolate, resistant to both carbapenems and colistin, harbored: gene and its two component regulatory genes for increased expression on the chromosome, on non-conjugative (yet co-transferable) ColE plasmid, and 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.