title: Characterization of small ColE-like plasmids mediating widespread dissemination of the qnrB19 gene in commensal enterobacteria.
abstract: In this work, we have characterized two small ColE-like plasmids (pECY6-7, 2.7 kb in size, and pECC14-9, of 3.0 kb), encoding the QnrB19 quinolone resistance determinant, that were carried by several clonally unrelated quinolone-resistant commensal Escherichia coli strains isolated from healthy children living in different urban areas of Peru and Bolivia. The two plasmids are closely related to each other and carry the qnrB19 gene as the sole resistance determinant, located in a conserved genetic context between the plasmid RNAII sequence (which controls plasmid replication) and the plasmid Xer site (involved in plasmid dimer resolution). ISEcp1-like or other putative insertion sequences are not present in the qnrB19-flanking regions or elsewhere on the plasmids. Since we previously observed a high prevalence (54%) of qnrB genes in the metagenomes of commensal enterobacteria from the same population of healthy children, the presence of pECY6-7- and pECC14-9-like plasmids in those qnrB-positive metagenomes was investigated by PCR mapping. Both plasmids were found to be highly prevalent (67% and 16%, respectively) in the qnrB-positive metagenomes, suggesting that dissemination of these small plasmids played a major role in the widespread dissemination of qnrB genes observed in commensal enterobacteria from healthy children living in those areas.
authors.affiliation: Dipartimento di Biologia Molecolare, Sezione di Microbiologia, Università di Siena, Policlinico Santa Maria alle Scotte, 53100 Siena, Italy.
authors.forename: Lucia
authors.initials: L
authors.lastname: Pallecchi
authors.forename: Eleonora
authors.initials: E
authors.lastname: Riccobono
authors.forename: Samanta
authors.initials: S
authors.lastname: Sennati
authors.forename: Antonia
authors.initials: A
authors.lastname: Mantella
authors.forename: Filippo
authors.initials: F
authors.lastname: Bartalesi
authors.forename: Christian
authors.initials: C
authors.lastname: Trigoso
authors.forename: Eduardo
authors.initials: E
authors.lastname: Gotuzzo
authors.forename: Alessandro
authors.initials: A
authors.lastname: Bartoloni
authors.forename: Gian Maria
authors.initials: GM
authors.lastname: Rossolini
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004251:DNA Transposable Elements / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D004755:Enterobacteriaceae / Q000187:drug effects* / Q000235:genetics*; D005838:Genotype; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics*; D016133:Polymerase Chain Reaction; D015363:Quinolones / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D004251:DNA Transposable Elements; D015363:Quinolones