Accession ARO:3003012
DefinitiondfrA13 is an integron-encoded dihydrofolate reductase found in Escherichia coli
AMR Gene Familytrimethoprim resistant dihydrofolate reductase dfr
Drug Classdiaminopyrimidine antibiotic
Resistance Mechanismantibiotic target replacement
Classification10 ontology terms | Show
Parent Term(s)2 ontology terms | Show

Ahmed MO, et al. 2010. Ann Clin Microbiol Antimicrob 9: 12. Antimicrobial resistance in equine faecal Escherichia coli isolates from North West England. (PMID 20374640)

Gassama A, et al. 2004. Microb Drug Resist 10(1): 27-30. Integron-associated antibiotic resistance in enteroaggregative and enteroinvasive Escherichia coli. (PMID 15140390)

Tang X, et al. 2011. Microb Pathog 50(5): 207-212. Antimicrobial resistances of extraintestinal pathogenic Escherichia coli isolates from swine in China. (PMID 21237262)


Prevalence of dfrA13 among the sequenced genomes, plasmids, and whole-genome shotgun assemblies available at NCBI for 85 important pathogens (see methodological details and complete list of analyzed pathogens). Values reflect percentage of genomes, plasmids, 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).

Prevalence: protein homolog model

SpeciesNCBI ChromosomeNCBI PlasmidNCBI WGS
No prevalence data

Detection Models

Model Type: protein homolog model

Model Definition: The protein homolog model is an AMR detection model. Protein homolog models detect a protein sequence based on its similarity to a curated reference sequence. A protein homolog model has only one parameter: a curated BLASTP bitscore cutoff for determining the strength of a match. Protein homolog model matches to reference sequences are categorized on three criteria: perfect, strict and loose. A perfect match is 100% identical to the reference sequence along its entire length; a strict match is not identical but the bitscore of the matched sequence is greater than the curated BLASTP bitscore cutoff. Loose matches are other sequences with a match bitscore less than the curated BLASTP bitscore.

Bit-score Cut-off (blastP): 300

>gb|CAA90683.1|+|dfrA13 [Escherichia coli]

>gb|Z50802|+|718-1215|dfrA13 [Escherichia coli]