Whole Genome Sequencing of a Citrobacter freundii Strain Isolated from the Hospital Environment: An Extremely Multiresistant NDM-1 and VIM-48 Coproducing Isolate

Citrobacter freundii has acquired resistance to several antimicrobial drugs, including last-resort antibiotics affecting, therefore, clinical efficacy and causing high rates of mortality. In this study, we investigate the whole genome sequence of a carbapenem-resistant C. freundii strain isolated from the hospital environment in Tunisia. A total of 210 samples were taken using sterile swabs, from inanimate surfaces, medical devices, and care staff, during the period extended between March and April 2019. After the microbiological analysis of samples and antimicrobial susceptibility testing, only one strain identified as C. freundii showing resistance to carbapenems was selected for the whole genome sequencing. The genome analysis revealed a high-level resistance to most antibiotics. Interestingly, we have noted the coexistence of blaNDM-1 and blaVIM-48 metallo-β-lactamase (MBL) encoding genes conferring resistance to carbapenems. Other β-lactamases encoding genes have also been detected, including blaTEM-1, blaCMY-48, and blaOXA-1. Moreover, genes conferring resistance to aminoglycoside [aac(3)-IId, ant(3″)-Ia, aadA, aac(6')-Ib], macrolide [mph(A)], sulfonamide (sul1), trimethoprim (dfrA1), tetracycline [tet(D)], chloramphenicol [cat(B3)], rifamycin (arr-3), and quinolone (qnrB) have been revealed. The multi-locus sequence typing analysis showed that this isolate could not be assigned to an existing sequence type (ST), but it is almost identical to ST22. The plasmid investigation revealed the presence of five plasmids belonging to diverse incompatibility groups (IncFII, IncHI1A, IncHI1B, IncN, and IncX3). To the best of our knowledge, our findings report the first detection of NDM-1 and VIM-48 coproducing C. freundii in Tunisia and the second detection in the world of the blaVIM-48.