title: R-factor-mediated resistance to tetracycline in Proteus mirabilis.
abstract: The expression of R-factor-mediated resistance to tetracycline has been compared in Proteus mirabilis and Escherichia coli. Resistance to a range of concentrations of tetracycline was significantly lower in P. mirabilis than in E. coli in both induced and repressed states. Indirect evidence showed that conditions which result in a marked increase in the level of resistance of P. mirabilis harboring the R factor NR1 to chloramphenicol, streptomycin, and spectinomycin due to an amplification in the number of copies of r-determinants per cell do not detectably increase the level of resistance to tetracycline. Tetracycline resistance was inducible in early stationary-phase P. mirabilis NR1 although not after 5 h in this state. Double isotope labeling of control and tetracycline-induced P. mirabilis NR1 in early stationary phase revealed isotopic enrichment of certain peaks in extracts from induced cells subjected to polyacrylamide gel electrophoresis.
mesh_terms: D000123:Acetyltransferases / Q000378:metabolism; D001426:Bacterial Proteins / Q000096:biosynthesis; D002247:Carbon Isotopes; D002701:Chloramphenicol / Q000494:pharmacology; D004352:Drug Resistance, Microbial; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000187:drug effects; D005827:Genetics, Microbial; D007930:Leucine / Q000378:metabolism; D011511:Proteus / Q000187:drug effects*; D011513:Proteus mirabilis / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D013045:Species Specificity; D000198:Spectinomycin / Q000494:pharmacology; D013307:Streptomycin / Q000494:pharmacology; D013449:Sulfonamides / Q000494:pharmacology; D013752:Tetracycline / Q000494:pharmacology*; D014316:Tritium
chemical_list: D001426:Bacterial Proteins; D002247:Carbon Isotopes; D013449:Sulfonamides; D014316:Tritium; D002701:Chloramphenicol; D000198:Spectinomycin; D000123:Acetyltransferases; D013752:Tetracycline; D007930:Leucine; D013307:Streptomycin