title: Genetic and proteomic characterization of rifaximin resistance in Bifidobacterium infantis BI07.
abstract: Rifaximin resistance in the probiotic strain Bifidobacterium infantis BI07 was studied to assess the use of an antibiotic-probiotic combination for clinical management of intestinal disorders. A rifaximin-resistant mutant was selected and a 129 bp core region of the rpoB gene was sequenced and compared with the respective sequence of the sensitive clone. A miss-sense mutation of codon 513, producing the substitution of Gln with Arg in the protein sequence, was found. The involvement of metabolic changes associated with rifaximin resistance was also investigated by proteomic analysis performed with two-dimensional electrophoresis and mass spectrometry. The principal categories of proteins, whose expression levels varied as a consequence of rifaximin resistance, included chaperonins, regulatory factors and metabolic enzymes. The hypothesis of rifaximin inactivation by bacterial enzymatic activities was excluded, as neither structural modifications nor degradation derivates of the drug moiety was identified using liquid chromatography coupled with tandem mass spectrometry.
authors.affiliation: Department of Pharmaceutical Sciences, CIRB-center for Biotechnology, University of Bologna, Via Belmeloro 6, 40126 Bologna, Italy.
authors.forename: Beatrice
authors.initials: B
authors.lastname: Vitali
authors.forename: Silvia
authors.initials: S
authors.lastname: Turroni
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Dal Piaz
authors.forename: Marco
authors.initials: M
authors.lastname: Candela
authors.forename: Valerie
authors.initials: V
authors.lastname: Wasinger
authors.forename: Patrizia
authors.initials: P
authors.lastname: Brigidi
mesh_terms: D000890:Anti-Infective Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001644:Bifidobacterium / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D012321:DNA-Directed RNA Polymerases / Q000235:genetics; D024881:Drug Resistance, Bacterial / Q000235:genetics; D015180:Electrophoresis, Gel, Two-Dimensional; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D013058:Mass Spectrometry; D009154:Mutation; D019936:Probiotics; D040901:Proteomics; D012294:Rifamycins / Q000494:pharmacology*; D000078262:Rifaximin
chemical_list: D000890:Anti-Infective Agents; D001426:Bacterial Proteins; D012294:Rifamycins; D012321:DNA-Directed RNA Polymerases; C105078:RNA polymerase beta subunit; D000078262:Rifaximin