| Accession | ARO:3004642 |
| CARD Short Name | dfrA3b |
| Definition | A dihydrofolate reductase that confers resistance to trimethoprim. |
| AMR Gene Family | trimethoprim resistant dihydrofolate reductase dfr |
| Drug Class | diaminopyrimidine antibiotic |
| Resistance Mechanism | antibiotic target replacement |
| Resistomes with Perfect Matches | Citrobacter freundiip, Klebsiella oxytocap, Klebsiella pneumoniaewgs, Shigella sonneiwgs |
| Resistomes with Sequence Variants | Citrobacter freundiip, Klebsiella oxytocap, Klebsiella pneumoniaewgs, Shigella sonneiwgs |
| Classification | 9 ontology terms | Show + process or component of antibiotic biology or chemistry + mechanism of antibiotic resistance + determinant of antibiotic resistance + antibiotic molecule + antibiotic target replacement [Resistance Mechanism] + antibiotic target replacement protein + diaminopyrimidine antibiotic [Drug Class] + antibiotic resistant dihydrofolate reductase + trimethoprim [Antibiotic] |
| Parent Term(s) | 2 ontology terms | Show + confers_resistance_to_antibiotic trimethoprim [Antibiotic] + trimethoprim resistant dihydrofolate reductase dfr [AMR Gene Family] |
| Publications | Arduino SM, et al. 2003. Antimicrob Agents Chemother 47(12): 3945-3949. Molecular epidemiology of orf513-bearing class 1 integrons in multiresistant clinical isolates from Argentinean hospitals. (PMID 14638506) |
Prevalence of dfrA3b among the sequenced genomes, plasmids, and whole-genome shotgun assemblies available at NCBI or IslandViewer for 413 important pathogens (see methodological details and complete list of analyzed pathogens). Values reflect percentage of genomes, plasmids, genome islands, or whole-genome shotgun assemblies that have at least one hit to the AMR detection model. Default view includes percentages calculated based on Perfect plus Strict RGI hits. Select the checkbox to view percentages based on only Perfect matches to AMR reference sequences curated in CARD (note: this excludes resistance via mutation as references in protein variant models are often wild-type, sensitive sequences).
| Species | NCBI Chromosome | NCBI Plasmid | NCBI WGS | NCBI GI |
|---|---|---|---|---|
| Citrobacter freundii | 0% | 0.62% | 0% | 0% |
| Klebsiella oxytoca | 0% | 0.68% | 0% | 0% |
| Klebsiella pneumoniae | 0% | 0% | 0.01% | 0% |
| Shigella sonnei | 0% | 0% | 0.44% | 0% |
Model Type: protein homolog model
Model Definition: Protein Homolog Models (PHM) detect protein sequences based on their similarity to a curated reference sequence, using curated BLASTP bitscore cut-offs. Protein Homolog Models apply to all genes that confer resistance through their presence in an organism, such as the presence of a beta-lactamase gene on a plasmid. PHMs include a reference sequence and a bitscore cut-off for detection using BLASTP. A Perfect RGI match is 100% identical to the reference protein sequence along its entire length, a Strict RGI match is not identical but the bit-score of the matched sequence is greater than the curated BLASTP bit-score cutoff, Loose RGI matches have a bit-score less than the curated BLASTP bit-score cut-off.
Bit-score Cut-off (blastP): 280