Comparison of dihydrofolate reductases from trimethoprim- and sulfonamide-resistant strains of Neisseria gonorrhoeae.
The dihydrofolate reductases were purified from Neisseria gonorrhoeae strains CDC 9 and 7134, for which MICs of trimethoprim differ twofold and MICs of sulfadiazine differ sixtyfold. Although affinities of the dihydropteroate synthetases from the two strains for sulfonamide were known to differ markedly, no conclusive difference in the extents of binding of trimethoprim by the dihydrofolate reductases from these organisms could be demonstrated. Thus, it was concluded that permeability of the cell envelope or increased production of dihydrofolate reductase may be an important factor among strains of N. gonorrhoeae that have low- and middle-range resistance to trimethoprim.
D000892:Anti-Infective Agents, Urinary / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D009344:Neisseria gonorrhoeae / Q000187:drug effects* / Q000201:enzymology*; D013449:Sulfonamides / Q000494:pharmacology*; D013762:Tetrahydrofolate Dehydrogenase / Q000378:metabolism*; D014295:Trimethoprim / Q000494:pharmacology*