title: Citrobacter freundii carrying blaKPC-2 and blaNDM-1: characterization by whole genome sequencing.
abstract: A carbapenem-resistant Citrobacter freundii strain WCHCF65 was recovered from hospital sewage and was characterized by genome sequencing and conjugation experiments. The strain carried nine genes encoding β-lactamases including two carbapenemase genes, blaNDM-1 and blaKPC-2. blaNDM-1 was carried on an IncX3 plasmid, which was identical to a plasmid found in a local Escherichia coli, suggesting interspecies horizontal transfer. blaKPC-2 was bracketed by two copies of insertion sequence ISKpn19, which could form a composite transposon with the potential to mobilize blaKPC-2, on a new type of plasmid. The coexistence of blaNDM-1 and blaKPC-2 conferred higher levels of resistance to carbapenems compared with blaNDM-1 or blaKPC-2 alone. The coexistence of these carbapenemase genes, on two different plasmids, in one strain may allow new genetic platforms to be generated to mediate their spread.
authors.affiliation: Center of Infectious Diseases, West China Hospital, Sichuan University, Chengdu, China.
authors.forename: Wenjing
authors.initials: W
authors.lastname: Wu
authors.affiliation: School of Medicine, Ingham Institute for Applied Medical Research, Western Sydney University, Penrith, Australia.
authors.forename: Björn
authors.initials: B
authors.lastname: Espedido
authors.affiliation: Center of Infectious Diseases, West China Hospital, Sichuan University, Chengdu, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Feng
authors.affiliation: Center of Infectious Diseases, West China Hospital, Sichuan University, Chengdu, China.
authors.forename: Zhiyong
authors.initials: Z
authors.lastname: Zong
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D015780:Carbapenems / Q000494:pharmacology; D016971:Citrobacter freundii / Q000201:enzymology* / Q000235:genetics* / Q000302:isolation & purification; D003227:Conjugation, Genetic; D004251:DNA Transposable Elements; D004926:Escherichia coli / Q000235:genetics; D022761:Gene Transfer, Horizontal; D006761:Hospitals; D010957:Plasmids / Q000032:analysis; D012722:Sewage / Q000382:microbiology; D000073336:Whole Genome Sequencing; D018440:beta-Lactam Resistance; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D000900:Anti-Bacterial Agents; D015780:Carbapenems; D004251:DNA Transposable Elements; D012722:Sewage; C491478:beta-lactamase KPC-2; D001618:beta-Lactamases; C552864:beta-lactamase NDM-1