title: A multidrug resistance regulatory chromosomal locus is widespread among enteric bacteria.
abstract: Constitutive expression of the mar operon (marRAB) in Escherichia coli produces a multiple antibiotic resistance phenotype mediated by the expression of multiple genetic loci in response to regulatory proteins in the operon. A mar-specific DNA probe was used to search for the operon in bacterial strains representing 53 species and 27 genera. Among these, 6 other Enterobacteriaceae, Salmonella, Shigella, Klebsiella, Citrobacter, Hafnia, and Enterobacter species, contained DNA sequences that hybridized to the probe under high-stringency conditions. By use of a selection protocol developed to obtain multiple antibiotic resistant mutants of E. coli, multiply resistant mutants that showed increased expression of mar-specific RNA were obtained from Enterobacter agglomerans and Salmonella species.
authors.affiliation: Center for Adaptation Genetics and Drug Resistance, Tufts University School of Medicine, Boston, MA 02111.
authors.forename: S P
authors.initials: SP
authors.lastname: Cohen
authors.forename: W
authors.initials: W
authors.lastname: Yan
authors.forename: S B
authors.initials: SB
authors.lastname: Levy
mesh_terms: D015152:Blotting, Northern; D015139:Blotting, Southern; D002876:Chromosomes, Bacterial; D004269:DNA, Bacterial / Q000032:analysis / Q000235:genetics; D004352:Drug Resistance, Microbial / Q000235:genetics; D004755:Enterobacteriaceae / Q000187:drug effects* / Q000235:genetics*; D004756:Enterobacteriaceae Infections / Q000382:microbiology; D009154:Mutation; D009876:Operon; D012045:Regulatory Sequences, Nucleic Acid; D012475:Salmonella / Q000187:drug effects / Q000235:genetics
chemical_list: D004269:DNA, Bacterial