OBJECTIVES: A new pentapeptide repeat (PRP) protein, named SmaQnr, from the clinically relevant species Serratia marcescens, which decreased susceptibility to quinolones when expressed in Escherichia coli, is reported herein. METHODS: In silico analysis revealed the presence of a gene encoding a Qnr-like protein that shares 80% amino acid identity with QnrB1 in the S. marcescens strain Db11. Fragments carrying the coding region and the upstream non-coding sequences of eight clinical isolates were cloned and expressed in E. coli. MIC values of quinolones were determined. RT-PCR was used to study expression of these genes in their natural host. Southern hybridization was used to explore the presence of the gene in the genus Serratia. RESULTS: Recombinant plasmids encoding SmaQnr reduced susceptibility to fluoroquinolones and nalidixic acid in both E. coli ATCC 25922 and DH10B. Sequences upstream of these genes contain a LexA box. Conventional RT-PCR showed transcription of the analysed Smaqnr genes in their natural hosts. Southern blot analysis suggests the presence of similar genes in several species of the genus Serratia. CONCLUSIONS: SmaQnr conferred a reduced susceptibility phenotype against fluoroquinolones in E. coli. These data provide evidence of its possible role in quinolone resistance in S. marcescens. This Gram-negative species may constitute a reservoir for qnr-like quinolone resistance genes.
OBJECTIVES: A new pentapeptide repeat (PRP) protein, named SmaQnr, from the clinically relevant species Serratia marcescens, which decreased susceptibility to quinolones when expressed in Escherichia coli, is reported herein. METHODS: In silico analysis revealed the presence of a gene encoding a Qnr-like protein that shares 80% amino acid identity with QnrB1 in the S. marcescens strain Db11. Fragments carrying the coding region and the upstream non-coding sequences of eight clinical isolates were cloned and expressed in E. coli. MIC values of quinolones were determined. RT-PCR was used to study expression of these genes in their natural host. Southern hybridization was used to explore the presence of the gene in the genus Serratia. RESULTS: Recombinant plasmids encoding SmaQnr reduced susceptibility to fluoroquinolones and nalidixic acid in both E. coli ATCC 25922 and DH10B. Sequences upstream of these genes contain a LexA box. Conventional RT-PCR showed transcription of the analysed Smaqnr genes in their natural hosts. Southern blot analysis suggests the presence of similar genes in several species of the genus Serratia. CONCLUSIONS: SmaQnr conferred a reduced susceptibility phenotype against fluoroquinolones in E. coli. These data provide evidence of its possible role in quinolone resistance in S. marcescens. This Gram-negative species may constitute a reservoir for qnr-like quinolone resistance genes.
Authors: Subray S Hegde; Matthew W Vetting; Lesley A Mitchenall; Anthony Maxwell; John S Blanchard Journal: Antimicrob Agents Chemother Date: 2010-10-11 Impact factor: 5.191
Authors: G Samonis; E K Vouloumanou; M Christofaki; D Dimopoulou; S Maraki; E Triantafyllou; D P Kofteridis; M E Falagas Journal: Eur J Clin Microbiol Infect Dis Date: 2011-01-10 Impact factor: 3.267
Authors: Fredrik Boulund; Anna Johnning; Mariana Buongermino Pereira; D G Joakim Larsson; Erik Kristiansson Journal: BMC Genomics Date: 2012-12-11 Impact factor: 3.969
Authors: Fredrik Boulund; Fanny Berglund; Carl-Fredrik Flach; Johan Bengtsson-Palme; Nachiket P Marathe; D G Joakim Larsson; Erik Kristiansson Journal: BMC Genomics Date: 2017-09-02 Impact factor: 3.969