Browse AMR Genes

Explore antimicrobial resistance genes from the literature

cfxA3

beta-lactamase

NCBI Pathogen Isolates

Bacterial genomes carrying this gene

NCBI Reference Gene Catalog

Known alleles and reference sequences

Protein entries specific to cfxA3

Browse AMR rules for cfxA3

Validation StatusConfirmed2+ DBs

Overview

Mechanism: Enzymatic inactivation
Validation Method: cloning in E. coli + MIC testing
Drug Classes: Ceftazidime, Cefotaxime, AMPICILLIN, CEPHALOSPORIN, Beta-lactams, Penicillin, Amoxicillin, Cephalosporin, Cefuroxime
Organisms: Capnocytophaga ochracea, Escherichia coli, Prevotella spp., Capnocytophaga spp., Porphyromonas spp., Bacteroides spp., Bacteroides, Alistipes indistinctus
Geographic Location: Japan, North America|Eastern Europe, Norway, South Africa
Alleles: 2
Papers: 6
Databases: Card DatabaseReference Gene CatalogResFinder DatabaseReslit

Allele Variants2

Allele	Database	Papers	Drug Classes	Organisms	Countries	Years	Sequence Accession	Protein Accession
CfxA3	Card DatabaseReference Gene CatalogResFinder DatabaseReslit	9	Ceftazidime, Cefotaxime +7	Capnocytophaga ochracea

Papers6

1

Genetic analysis of an ambler class A extended-spectrum beta-lactamase from Capnocytophaga ochracea.

PMID 14766881 · 2004

The study identifies and characterizes the cfxA3 gene, encoding an Ambler class A extended-spectrum beta-lactamase from Capnocytophaga ochracea, which confers resistance to ceftazidime and cefotaxime.

Gene Information

Gene Name: cfxA3
Allele: CfxA3
Encodes: beta-lactamase
Source Database: Reslit
Confers Resistance To: CeftazidimeCefotaxime
Organisms Tested In: • Capnocytophaga ochracea
• Escherichia coli
Validation Method: cloning in E. coli + MIC testing
Sequence Accession: AF472622

2

Genetic analysis of an ambler class A extended-spectrum beta-lactamase from Capnocytophaga ochracea.

PMID 14766881 · 2004

Gene Information

Gene Name: cfxA3
Allele: CfxA3
Encodes: extended-spectrum class A beta-lactamase CfxA3
Source Database: Reference Gene Catalog
Mechanism: Enzymatic inactivation
Confers Resistance To: AMPICILLINCEPHALOSPORIN
Organisms Tested In: • Capnocytophaga ochracea
Sequence Accession: AF472622.2
Protein Accession: AAL79549.2
Notes: Chromosomal

3

Genetic analysis of an ambler class A extended-spectrum beta-lactamase from Capnocytophaga ochracea.

PMID 14766881 · 2004

Gene Information

Gene Name: cfxA3
Allele: CfxA3
Encodes: extended-spectrum class A beta-lactamase CfxA3
Source Database: ResFinder Database
Mechanism: Enzymatic inactivation
Confers Resistance To: AMPICILLINCEPHALOSPORIN
Organisms Tested In: • Capnocytophaga ochracea
Sequence Accession: AF472622.2
Protein Accession: AAL79549.2
Notes: Chromosomal

4

Genetic analysis of an ambler class A extended-spectrum beta-lactamase from Capnocytophaga ochracea.

PMID 14766881 · 2004

Gene Information

Gene Name: cfxA3
Allele: CfxA3
Encodes: extended-spectrum class A beta-lactamase CfxA3, CfxA beta-lactamase
Source Database: Card Database
Mechanism: Enzymatic inactivation, antibiotic inactivation
Confers Resistance To: AMPICILLINCEPHALOSPORIN
Organisms Tested In: • Capnocytophaga ochracea
Sequence Accession: AF472622.2
Protein Accession: AAL79549.2
Notes: Chromosomal, ARO:3003003

5

Genetic analysis of an ambler class A extended-spectrum beta-lactamase from Capnocytophaga ochracea.

PMID 14766881 · 2004

Gene Information

Gene Name: cfxA3
Allele: cfxA3
Source Database: ResFinder Database
Mechanism: Enzymatic inactivation
Confers Resistance To: AMPICILLIN
Organisms Tested In: • Capnocytophaga ochracea
Sequence Accession: AF472622
Notes: Chromosomal

6

Metagenomic Analysis of Antibiotic Resistance Genes in Dairy Cow Feces following Therapeutic Administration of Third Generation Cephalosporin.

PMID 26258869 · 2015

Ceftiofur treatment led to an increase in β-lactam resistance genes, including CfxA2 and CfxA3, in dairy cow feces, indicating a rapid and measurable impact on the fecal metagenome.

Gene Information

Gene Name: cfxA3
Allele: CfxA3
Encodes: Class A beta-lactamase
Source Database: Reslit
Confers Resistance To: Beta-lactams
Organisms Tested In: • Prevotella spp.
• Capnocytophaga spp.
Validation Method: metagenomic analysis

7

Detection of cfxA2, cfxA3, and cfxA6 genes in beta-lactamase producing oral anaerobes.

PMID 27119762 · 2016

The study identified cfxA2, cfxA3, and cfxA6 genes in beta-lactamase-producing oral anaerobes, with 76.7%, 14%, and 9.3% of isolates carrying these genes, respectively. These genes conferred resistance to penicillin and amoxicillin.

Gene Information

Gene Name: cfxA3
Allele: CfxA3
Encodes: beta-lactamase
Source Database: Reslit
Confers Resistance To: PenicillinAmoxicillin
Organisms Tested In: • Prevotella spp.
• Porphyromonas spp.
• Bacteroides spp.
Geographic Location: South Africa
Validation Method: PCR and sequencing
Sequence Accession: AM940016|AY860640|FN376426

8

Ribaxamase, an Orally Administered beta-lactamase, Diminishes Changes to Acquired Antimicrobial Resistance of the Gut Resistome in Patients Treated with Ceftriaxone.

PMID 32801790 · 2020

The study identified several beta-lactamase and vancomycin resistance genes that were significantly increased in placebo-treated patients compared to ribaxamase-treated patients following ceftriaxone exposure.

Gene Information

Gene Name: cfxA3
Allele: CfxA3
Encodes: beta-lactamase
Source Database: Reslit
Confers Resistance To: Cephalosporin
Organisms Tested In: • Escherichia coli
Geographic Location: North America|Eastern Europe
Validation Method: whole-genome shotgun sequencing and qPCR
Sequence Accession: PRJNA589866

9

Differential response to prolonged amoxicillin treatment: long-term resilience of the microbiome versus long-lasting perturbations in the gut resistome.

PMID 36576106 · 2023

The study found that prolonged amoxicillin treatment leads to an increase in the abundance and diversity of antimicrobial resistance genes (ARGs) in the gut microbiome, particularly beta-lactamase genes such as cfxA and its variants, as well as tetracycline and macrolide resistance genes.

Gene Information

Gene Name: cfxA3
Allele: CfxA3
Encodes: beta-lactamase
Source Database: Reslit
Confers Resistance To: Beta-lactams
Organisms Tested In: • Bacteroides
Geographic Location: Norway
Validation Method: shotgun metagenomic sequencing

10

Alistipes Bacteremia in Older Patients with Digestive and Cancer Comorbidities, Japan, 2016-2023.

PMID 40133031 · 2025

The study identified several antimicrobial resistance genes in Alistipes strains, including adeF, tet(Q), cfxA3, cfxA4, and ermG, which confer resistance to various antibiotics such as minocycline, cefuroxime, and clindamycin.

Gene Information

Gene Name: cfxA3
Allele: CfxA3
Encodes: cephalosporinase
Source Database: Reslit
Confers Resistance To: Cefuroxime
Organisms Tested In: • Alistipes indistinctus
Geographic Location: Japan
Validation Method: antimicrobial susceptibility testing