Browse AMR Genes

Explore antimicrobial resistance genes from the literature

ResLit

folA

NCBI Pathogen Isolates

Bacterial genomes carrying this gene

NCBI Reference Gene Catalog

Known alleles and reference sequences

UniProt

Protein entries specific to folA

AMR Rules

Browse AMR rules for folA

Overview

Drug Classes: Trimethoprim, TRIMETHOPRIM, Trimethoprim/sulfamethoxazole, Cotrimoxazole, Trimethoprim-sulfamethoxazole
Organisms: Escherichia coli, Haemophilus influenzae, Streptococcus pneumoniae, non-typeable Haemophilus, Brucella melitensis
Papers: 14
Mutations: 36

Mutations

Protein Change	Nucleotide Change	Mechanism	Organism	Resistance To	Database	Validation Status
N147D	-	resistance	Escherichia coli	Trimethoprim	Reslit	Candidate
Y151D	-	-	Escherichia coli	Trimethoprim	Reslit	Candidate
L28R	-	resistance, increased substrate affinity	Escherichia coli	Trimethoprim	Reslit

Papers14

Directed evolution of multiple genomic loci allows the prediction of antibiotic resistance.

PMID 29871954 · 2018

Mutations in folA were identified as conferring resistance to trimethoprim.

Mutation Information

folA: p.N147D folA: p.L28R folA: p.A26S folA: p.P39R folA: p.W30C folA: p.P21P folA: p.A26D folA: p.C132G folA: p.A26T folA: p.H45R

Protein Change: N147D, L28R, A26S, P39R, W30C, P21P, A26D, C132G, A26T, H45R
Organisms: Escherichia coli
Confers Resistance To: Trimethoprim
Effect on Function: resistance
Source Database: Reslit

Proteostasis modulates gene dosage evolution in antibiotic-resistant bacteria.

PMID 40073078 · 2025

Mutations in folA were found to confer resistance to trimethoprim.

Mutation Information

folA: p.Y151D folA: p.W30R folA: c.A-64T folA: c.C-35T

Protein Change: Y151D, W30R
Nucleotide Change: A-64T, C-35T
Organisms: Escherichia coli
Confers Resistance To: Trimethoprim
Source Database: Reslit

Title of the Paper

PMID 32571917 · 2023

dominant mutation

Mutation Information

folA: p.L28R

Protein Change: L28R
Confers Resistance To: Trimethoprim
Source Database: Reslit

Assessment of trimethoprim-sulfamethoxazole susceptibility testing methods for fastidious Haemophilus spp.

PMID 31811916 · 2020

folA

Mutation Information

folA: p.F154V folA: p.F154S folA: p.I95L

Protein Change: F154V, F154S, I95L
Organisms: Haemophilus influenzae
Confers Resistance To: TRIMETHOPRIM
Effect on Function: type 3 dihydrofolate reductase FolA
Source Database: Reference Gene Catalog

Adaptation and compensation in a bacterial gene regulatory network evolving under antibiotic selection.

PMID 34591012 · 2021

Mutations in folA contribute to trimethoprim resistance, but are less frequent than mgrB mutations.

Mutation Information

folA: p.W30G folA: p.D27E folA: p.W30R

Protein Change: W30G, D27E, W30R
Confers Resistance To: Trimethoprim
Source Database: Reslit

Multiple Novel Traits without Immediate Benefits Originate in Bacteria Evolving on Single Antibiotics.

PMID 34865131 · 2022

Mutations in folA confer resistance to trimethoprim.

Mutation Information

folA: p.W30R folA: p.A26T folA: p.W30G

Protein Change: W30R, A26T, W30G
Organisms: Escherichia coli
Confers Resistance To: Trimethoprim
Source Database: Reslit

Antimicrobial resistance determinants and susceptibility profiles of pneumococcal isolates recovered in Trinidad and Tobago.

PMID 28818574 · 2017

When combined with the folP insertion, the I100L substitution in folA results in a resistant phenotype (MIC ≥ 4 mg/L).

Mutation Information

folA: p.I100L

Protein Change: I100L
Confers Resistance To: Trimethoprim/sulfamethoxazole
Source Database: Reslit

Characterization of Pneumococcal Colonization Dynamics and Antimicrobial Resistance Using Shotgun Metagenomic Sequencing in Intensively Sampled South African Infants.

PMID 33072693 · 2020

Mutation Information

folA: p.I100L

Protein Change: I100L
Organisms: Streptococcus pneumoniae
Confers Resistance To: Cotrimoxazole
Source Database: Reslit

Strength of selection pressure is an important parameter contributing to the complexity of antibiotic resistance evolution.

PMID 24962091 · 2014

Mutations in folA confer resistance to trimethoprim.

Mutation Information

folA: p.G123R

Protein Change: G123R
Organisms: Escherichia coli
Confers Resistance To: Trimethoprim
Source Database: Reslit

TMP-Free Enzymatic Velocities of DHFR Mutants Correlate Well with TMP-Free Growth Rates of E. coli Mutants Carrying Corresponding DHFR Mutations

PMID 30982891 · 2023

Mutations in the folA gene encoding DHFR are responsible for TMP resistance

Mutation Information

folA: p.W30G folA: p.W30R folA: p.I94L folA: p.P21L folA: p.A26T folA: p.L28R folA: c.C-15A folA: c.C-35T folA: c.G-31A folA: c.G-9A

Protein Change: W30G, W30R, I94L, P21L, A26T, L28R
Nucleotide Change: C-15A, C-35T, G-31A, G-9A
Confers Resistance To: Trimethoprim
Source Database: Reslit

Molecular characterization of multidrug-resistant non-typeable Haemophilus influenzae with high-level resistance to cefuroxime, levofloxacin, and trimethoprim-sulfamethoxazole.

PMID 37407940 · 2023

Mutation Information

folA: p.M21I folA: p.K107Q folA: p.L67P folA: p.I95L folA: p.N13S folA: p.N84Y

Protein Change: M21I, K107Q, L67P, I95L, N13S, N84Y
Organisms: non-typeable Haemophilus
Confers Resistance To: Trimethoprim-sulfamethoxazole
Source Database: Reslit

Kinetic Barrier to Enzyme Inhibition Is Manipulated by Dynamical Local Interactions in E. coli DHFR.

PMID 37491825 · 2023

The L28R mutation in the folA gene was shown to confer resistance to trimethoprim.

Mutation Information

folA: p.L28R

Protein Change: L28R
Organisms: Escherichia coli
Confers Resistance To: Trimethoprim
Effect on Function: increased substrate affinity
Source Database: Reslit

Whole-genome sequencing and antimicrobial resistance in Brucella melitensis from a Norwegian perspective.

PMID 29867163 · 2018

Mutation in folA was not associated with trimethoprim resistance as determined by phenotypic testing.

Mutation Information

folA: p.R217L

Protein Change: R217L
Organisms: Brucella melitensis
Confers Resistance To: Trimethoprim
Source Database: Reslit

Holistic understanding of trimethoprim resistance in Streptococcus pneumoniae using an integrative approach of genome-wide association study, resistance reconstruction, and machine learning.

PMID 39120145 · 2024

Mutations in intergenic region upstream of sulABCD operon lead to increased expression of sulA

Mutation Information

folA: p.I100L / c.A300C folA: p.T164S / c.C493G folA: p.P70S / c.CCC->AGC folA: p.M53I / c.G161T folA: p.L135F / c.G407C

Protein Change: I100L, T164S, P70S, M53I, L135F
Nucleotide Change: A300C, C493G, CCC->AGC, G161T, G407C
Organisms: Streptococcus pneumoniae
Confers Resistance To: Trimethoprim
Source Database: Reslit