Type B NfxB

Accession ARO:3004060
CARD Short NameType_B_NfxB
DefinitionType B NfxB mutants are more resistant to tetracycline and chloramphenicol, as well as ofloxacin, erythromycin, and the new zwitterionic cephems, than was PAO1, and they are four to eight times more susceptible to carbenicillin, sulbenicillin, imipenem, panipenem, biapenem, moxalactam, aztreonam, gentamicin, and kanamycin than PAO1. The mutation at the 46th amino acid position is sufficient for overproduction of OprJ and the multidrug resistance. nfxB corresponds to 2 loci in Pseudomonas aeruginosa PAO1 (gene name: esrC/nfxB) and 2 loci in Pseudomonas aeruginosa LESB58 (gene name: nfxB).
AMR Gene Familyresistance-nodulation-cell division (RND) antibiotic efflux pump
Drug Classtetracycline antibiotic, phenicol antibiotic, aminoglycoside antibiotic, aminocoumarin antibiotic, diaminopyrimidine antibiotic, penam, cephalosporin, macrolide antibiotic, fluoroquinolone antibiotic
Resistance Mechanismantibiotic efflux
Efflux Componentefflux pump complex or subunit conferring antibiotic resistance
Efflux Regulatorprotein(s) and two-component regulatory system modulating antibiotic efflux
Classification29 ontology terms | Show
Parent Term(s)3 ontology terms | Show

Srikumar R, et al. 1998. Antimicrob Agents Chemother 42(1): 65-71. Expression of Pseudomonas aeruginosa multidrug efflux pumps MexA-MexB-OprM and MexC-MexD-OprJ in a multidrug-sensitive Escherichia coli strain. (PMID 9449262)

Masuda N, et al. 1996. Antimicrob. Agents Chemother. 40(4):909-13 Quantitative correlation between susceptibility and OprJ production in NfxB mutants of Pseudomonas aeruginosa. (PMID 8849250)


Prevalence of Type B NfxB 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).

Prevalence: protein overexpression model

SpeciesNCBI ChromosomeNCBI PlasmidNCBI WGSNCBI GI
No prevalence data

Detection Models

Model Type: protein overexpression model

Model Definition: Protein Overexpression Models (POM) are similar to Protein Variant Models (PVM) in that they include a protein reference sequence, a curated BLASTP bitscore cut-off, and mapped resistance variants. Whereas PVMs are designed to detect AMR acquired via mutation of house-keeping genes or antibiotic targets, reporting only those with curated mutations conferring AMR, POMs are restricted to regulatory proteins and report both wild-type sequences and/or sequences with mutations leading to overexpression of efflux complexes. The former lead to efflux of antibiotics at basal levels, while the latter can confer clinical resistance. POMs include a protein reference sequence (often from wild-type alleles), a curated bit-score cut-off, and mapped resistance variants. Mapped resistance variants may include any or all of single point mutations, insertions, or deletions curated from the scientific literature. A Perfect RGI match is 100% identical to the wild-type reference protein sequence along its entire length, a Strict RGI match has a BLASTP bit-score above the curated BLASTP cutoff value may or may not contain at least one curated mutation from amongst the mapped resistance variants, while a Loose RGI match has a bit-score less than the curated BLASTP bit-score cut-off may or may not contain at least one curated mutation from amongst the mapped resistance variants.

Bit-score Cut-off (blastP): 310


  • discovered in clinical, agricultural, or environmental isolates

  • discovered via laboratory selection experiments

  • ReSeqTB https://platform.reseqtb.org

Published Variants:

PMID in progress (single): H87R

>gb|AAG07988.1|+|Type B NfxB [Pseudomonas aeruginosa PAO1]

>gb|AE004091.2|+|5155561-5156124|Type B NfxB [Pseudomonas aeruginosa PAO1]