title: Distribution in nature of R factors that increase susceptibility to rifampin of rif-r mutants in Escherichia coli.
abstract: Among 117 gram-negative bacteria isolated from pathological materials, 46 were found to carry antibiotic resistances transferable to Escherichia coli K-12; we therefore concluded that they carry infectious R factors. When transferred to a type of rifampin-resistant mutant of E. coli, all these R factors decreased the resistance to rifampin, but only 10% of them lowered the resistance to one-tenth or less that of the isogenic R(-) strain. The relevance of these facts for the epidemiology of R factors in gram-negative bacteria is discussed.
authors.forename: R
authors.initials: R
authors.lastname: Scotti
authors.forename: L G
authors.initials: LG
authors.lastname: Silvestri
authors.forename: E
authors.initials: E
authors.lastname: Romero
mesh_terms: D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics*; D009154:Mutation; D011815:R Factors; D012293:Rifampin / Q000494:pharmacology*
chemical_list: D012293:Rifampin