title: Development and analysis of furazolidone-resistant Escherichia coli mutants.
abstract: Furazolidone-resistant mutants were obtained from four clinical isolates of diarrhoeagenic Escherichia coli. The stability of the resistance and the frequency of mutation were established. The minimal inhibitory concentration of furazolidone, nitrofurantoin, nalidixic acid, ampicillin, chloramphenicol and tetracycline was established both in the presence and absence of the efflux pump inhibitor Phe-Arg-β-Naphtylamyde. The presence of mutations in the nitroreductase genes nfsA and nfsB was analysed by PCR; sequencing and their enzymatic activity was assessed by a spectrophotometric assay. Alterations in outer membrane proteins were studied by SDS-PAGE. The frequency of mutation ranged from <9.6 × 10(-10) to 9.59 × 10(-7) . Neither an effect on efflux pumps inhibited by Phe-Arg-β-Naphtylamyde nor cross-resistance with the antibiotics studied was observed. Nineteen mutants (52.94%) presented mutations in the nitroreductase-encoding genes: 17 in the nfsA gene (15 mutants with an internal stop codon, 2 with amino acid changes), 2 in the nfsB (all amino acid changes). Alterations in the outer membrane proteins OmpA and OmpW were also observed. Although more studies are necessary to find other resistance mechanisms, present data showed the low potential of selecting furazolidone-resistant mutants, together with the lack of cross-resistance with unrelated antimicrobial agents.
authors.affiliation: ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic - Universitat de Barcelona, Barcelona, Spain.
authors.forename: Sandra
authors.initials: S
authors.lastname: Martínez-Puchol
authors.affiliation: ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic - Universitat de Barcelona, Barcelona, Spain.
authors.forename: Cláudia
authors.initials: C
authors.lastname: Gomes
authors.affiliation: ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic - Universitat de Barcelona, Barcelona, Spain.
authors.forename: Maria J
authors.initials: MJ
authors.lastname: Pons
authors.affiliation: ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic - Universitat de Barcelona, Barcelona, Spain.
authors.forename: Lidia
authors.initials: L
authors.lastname: Ruiz-Roldán
authors.affiliation: ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic - Universitat de Barcelona, Barcelona, Spain.
authors.forename: Alba
authors.initials: A
authors.lastname: Torrents de la Peña
authors.affiliation: Instituto de Medicina Tropical Alexander von Humboldt, Universidad Peruana Cayetano Heredia, Lima, Peru.|Center for Infectious Diseases, University of Texas School of Public Health, Houston, TX, USA.
authors.forename: Theresa J
authors.initials: TJ
authors.lastname: Ochoa
authors.affiliation: ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic - Universitat de Barcelona, Barcelona, Spain.
authors.forename: Joaquim
authors.initials: J
authors.lastname: Ruiz
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D004151:Dipeptides; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics*; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000235:genetics; D005664:Furazolidone / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D009154:Mutation; D009601:Nitroreductases / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D001425:Bacterial Outer Membrane Proteins; D004151:Dipeptides; D029968:Escherichia coli Proteins; C064035:ompW protein, E coli; C048251:phenylalanylarginine; C078167:OMPA outer membrane proteins; D005664:Furazolidone; C116053:NfsA protein, E coli; C116054:NfsB protein, E coli; D009601:Nitroreductases
keywords: Enterobacteriaceae; Nitrofuran; resistance mechanisms