title: Characterization of IncI1 sequence type 71 epidemic plasmid lineage responsible for the recent dissemination of CTX-M-65 extended-spectrum β-lactamase in the Bolivian Chaco region.
abstract: During the last decade, a significant diffusion of CTX-M-type extended-spectrum β-lactamases (ESBLs) was observed in commensal Escherichia coli from healthy children in the Bolivian Chaco region, with initial dissemination of CTX-M-2, which was then replaced by CTX-M-15 and CTX-M-65. In this work, we demonstrate that the widespread dissemination of CTX-M-65 observed in this context was related to the polyclonal spreading of an IncI1 sequence type 71 (ST71) epidemic plasmid lineage. The structure of the epidemic plasmid population was characterized by complete sequencing of four representatives and PCR mapping of the remainder (n = 16). Sequence analysis showed identical plasmid backbones (similar to that of the reference IncI1 plasmid, R64) and a multiresistance region (MRR), which underwent local microevolution. The MRR harbored genes responsible for resistance to β-lactams, aminoglycosides, florfenicol, and fosfomycin (with microevolution mainly consisting of deletion events of resistance modules). The bla CTX-M-65 module harbored by the IncI1 ST71 epidemic plasmid was apparently derived from IncN-type plasmids, likely via IS26-mediated mobilization. The plasmid could be transferred by conjugation to several different enterobacterial species (Escherichia coli, Cronobacter sakazakii, Enterobacter cloacae, Klebsiella oxytoca, Klebsiella pneumoniae, and Salmonella enterica) and was stably maintained without selective pressure in these species, with the exception of K. oxytoca and S. enterica. Fitness assays performed in E. coli recipients demonstrated that the presence of the epidemic plasmid was apparently not associated with a significant biological cost.
authors.affiliation: Department of Medical Biotechnologies, University of Siena, Siena, Italy.
authors.forename: Eleonora
authors.initials: E
authors.lastname: Riccobono
authors.affiliation: Department of Medical Biotechnologies, University of Siena, Siena, Italy Department of Surgery and Translational Medicine, University of Florence, Florence, Italy.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Di Pilato
authors.affiliation: Department of Medical Biotechnologies, University of Siena, Siena, Italy.
authors.forename: Tiziana
authors.initials: T
authors.lastname: Di Maggio
authors.affiliation: Instituto Nacional de Laboratorios de Salud "Dr. Nestor Morales Villazón" (INLASA), La Paz, Bolivia.
authors.forename: Carmen
authors.initials: C
authors.lastname: Revollo
authors.affiliation: Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy Infectious and Tropical Diseases Unit, Careggi University Hospital, Florence, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Bartoloni
authors.affiliation: Department of Medical Biotechnologies, University of Siena, Siena, Italy.
authors.forename: Lucia
authors.initials: L
authors.lastname: Pallecchi
authors.affiliation: Department of Medical Biotechnologies, University of Siena, Siena, Italy Department of Experimental and Clinical Medicine, University of Florence, Florence, Italy Clinical Microbiology and Virology Unit, Careggi University Hospital, Florence, Italy gianmaria.rossolini@unifi.it.
authors.forename: Gian Maria
authors.initials: GM
authors.lastname: Rossolini
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D016972:Enterobacter cloacae / Q000187:drug effects / Q000201:enzymology / Q000235:genetics; D004755:Enterobacteriaceae / Q000187:drug effects / Q000201:enzymology / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology / Q000235:genetics; D005578:Fosfomycin / Q000494:pharmacology; D041121:Klebsiella oxytoca / Q000187:drug effects / Q000201:enzymology / Q000235:genetics; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000201:enzymology / Q000235:genetics; D008826:Microbial Sensitivity Tests; D010957:Plasmids / Q000235:genetics*; D019779:Salmonella enterica / Q000187:drug effects / Q000201:enzymology / Q000235:genetics; D001618:beta-Lactamases / Q000235:genetics* / Q000378:metabolism; D047090:beta-Lactams / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D047090:beta-Lactams; D005578:Fosfomycin; D001618:beta-Lactamases