QnrB9 in Association with TEM-116 Extended-Spectrum Beta-Lactamase in Citrobacter freundii Isolated from Sewage Effluent: First Report from Italy

• Published in: Journal of chemotherapy (Florence) 2010-08, Vol.22 (4), p.243-245
• Main Authors: Forcella, C., Pellegrini, C., Celenza, G., Segatore, B., Calabrese, R., Tavío, M.M., Amicosante, G., Perilli, M.
• Format: Article
• Language: English
• Subjects: Antibiotics. Antiinfectious agents. Antiparasitic agents; beta-Lactam Resistance - genetics; beta-Lactamases - genetics; Biological and medical sciences; Citrobacter freundii - genetics; Electroporation; environment; ESβL; Genes, Bacterial - genetics; Isoelectric Focusing; Italy; Medical sciences; Microbial Sensitivity Tests; Mutation; Pharmacology. Drug treatments; Plasmids - genetics; Polymerase Chain Reaction; quinolones; Resistance; Sewage - microbiology
• ISSN: 1120-009X; 1973-9478
• DOI: 10.1179/joc.2010.22.4.243

The aim of the present study was to investigate the mechanism of quinolone and ?β-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? β-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 β-lactamase (ESβL) production. This is the first finding in Italy of qnrB9 and TEM-116 in a non-clinical or animal strain.