title: QnrB9 in association with TEM-116 extended-spectrum beta-lactamase in Citrobacter freundii isolated from sewage effluent: first report from Italy.
abstract: The aim of the present study was to investigate the mechanism of quinolone and beta-lactam resistance in an isolate of Citrobacter freundii PC2/08 collected from sewage effluent from l'Aquila, Italy. QnrB-9 and bla(TEM-116 )were co-expressed in a large plasmid identified in C. freundi PC2/08 strain. Compared to TEM-1, TEM-116 showed two single mutations: V84I and A184V. The plPC2/08 plasmid conferred resistance to several beta-lactams and fluoroquinolones. Tazobactam could be considered a good inhibitor whereas clavulanic acid was unable to restore susceptibility to amoxicillin. The QnrB-9 element seems to confer the same level of resistance to levofloxacin and ciprofloxacin with minimum inhibitory concentration (MIC) values of 4 mg/l for either. In this study, we confirm the common association of plasmid-mediated quinolone resistance with extended-spectrum beta-lactamase (ESbetaL) production. This is the first finding in Italy of qnrB9 and TEM-116 in a non-clinical or animal strain.
authors.affiliation: Dipartimento di Scienze e Tecnologie Biomediche, University of L'Aquila, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Forcella
authors.forename: C
authors.initials: C
authors.lastname: Pellegrini
authors.forename: G
authors.initials: G
authors.lastname: Celenza
authors.forename: B
authors.initials: B
authors.lastname: Segatore
authors.forename: R
authors.initials: R
authors.lastname: Calabrese
authors.forename: M M
authors.initials: MM
authors.lastname: Tavio
authors.forename: G
authors.initials: G
authors.lastname: Amicosante
authors.forename: M
authors.initials: M
authors.lastname: Perilli
mesh_terms: D016971:Citrobacter freundii / Q000235:genetics*; D018274:Electroporation; D005798:Genes, Bacterial / Q000235:genetics*; D007525:Isoelectric Focusing; D007558:Italy; D008826:Microbial Sensitivity Tests; D009154:Mutation; D010957:Plasmids / Q000235:genetics; D016133:Polymerase Chain Reaction; D012722:Sewage / Q000382:microbiology*; D018440:beta-Lactam Resistance / Q000235:genetics*; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D012722:Sewage; D001618:beta-Lactamases