High Plasticity of Multi-Drug Resistant ST258 .

Carbapenemase production in Enterobacterales clinical isolates is a global threat. Multi-drug resistant harboring carbapenemases are a major concern among the hospital settings in Latin America. The aim of this study was to analyze the genetic relatedness between three isolates of recovered from one patient in the same bacteriological round on the same day, which exhibited different susceptibility profiles to carbapenems (CP) and to colistin (Col). Isolates' profiles were as follows (susceptible-S/resistant-R): CP/Col, CP/Col, and CP/Col. Pulse-field gel electrophoresis, multilocus sequence typing, and whole genome sequencing were performed. Conjugation assays were carried out and PCR determination in transconjugants (Tcs) was made for: , , , , alleles, , , and plasmid incompatibility groups (Inc). All isolates belonged to the same clone, to ST258 and harbored , , , , , and (capsule-locus KL107). One isolate had additional gene, (capsule-locus KL36). In CP isolates, the pattern was explained for or / presence, and in Col for IS-like element insertion in at different positions. Co-mobilization of / was associated to a different plasmid Inc (A/C-FII) in both donors. Mobilization of was related to IncI1 in one donor. These findings highlight the potential plasticity of ST258 clone. To the best of our knowledge, this is the first description of /-producing ST258 in Latin America.