Sulfonamide resistance mechanism in Escherichia coli: R plasmids can determine sulfonamide-resistant dihydropteroate synthases.
Several natural isolate E. coli strains highly resistant to sulfonamides and antibiotics are shown to contain a sulfonamide-resistant dihydropteroate synthase (2-amino-4-hydroxy-6-hydroxymethyl-7,8-dihydropteridine-diphosphate:4-aminobenzoate 2-amino-4-hydroxydihydropteridine-6-methenyltransferase, EC 2.5.1.15) in addition to the normal sensitive enzyme. The resistant dihydropteroate synthases examined are determined by an R plasmid and are smaller and less heat stable than the normal sulfonamide-sensitive enzyme. One synthase resistant to any sulfonamide tested, and to sulfanilic and arsanilic acids, was still inhibited by several non-sulfonamide analogs of p-aminobenzoate. Citrobacter and Klebsiella pneumoniae strains also show similar mechanisms of sulfonamide resistance.
D062365:Aminobenzoates / Q000494:pharmacology; D000667:Ampicillin / Q000494:pharmacology; D002954:Citrobacter / Q000187:drug effects / Q000378:metabolism; D004094:Dihydropteroate Synthase / Q000378:metabolism*; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology*; D005111:Extrachromosomal Inheritance / Q000187:drug effects*; D006358:Hot Temperature; D010403:Penicillin Resistance; D010957:Plasmids / Q000187:drug effects*; D013045:Species Specificity; D013432:Sulfathiazoles / Q000494:pharmacology; D013449:Sulfonamides / Q000494:pharmacology*; D013997:Time Factors; D014166:Transferases / Q000378:metabolism*
D062365:Aminobenzoates; D013432:Sulfathiazoles; D013449:Sulfonamides; D000667:Ampicillin; D014166:Transferases; D004094:Dihydropteroate Synthase