The region upstream of the multiple antibiotic resistance efflux operon mexA-mexB-oprM in Pseudomonas aeruginosa was sequenced, and a gene, mexR, was identified. The predicted MexR product contains 147 amino acids with a molecular mass of 16,964 Da, which is consistent with the observed size of the overexpressed mexR gene product. MexR was homologous to MarR, the repressor of MarA-dependent mul...

OBJECTIVES To investigate the mechanisms of carbapenem resistance in the 175 Pseudomonas aeruginosa isolates (39%; 175/448) showing non-susceptibility (European Committee on Antimicrobial Susceptibility Testing breakpoints) to imipenem (35%), meropenem (33%) and/or doripenem (33%) recovered in 2008-09 from 16 Spanish hospitals during the Comparative Activity of Carbapenem Testing (COMPACT) surv...

BACKGROUND Holarrhena antidysenterica has been employed as an ethnobotanical plant for the treatment of dysentery, diarrhoea, fever, and bacterial infections. Biological activities of the principle compound, conessine including anti-diarrhoea and anti-plasmodial effects were documented. Our previous study reported potency of Holarrhena antidysenterica extract and conessine as resistance modifyi...

MexA-MexB-OprM is an efflux system in Pseudomonas aeruginosa. OprM overproduced from the cloned gene was able to complement OprM-deficient mutants but did not alter the resistance of a wild-type P. aeruginosa strain to the different antimicrobial agents tested. This suggests that OprM cannot function by itself to efflux antibiotics, including beta-lactams targeted to the periplasm.

An intragenic probe derived from the multidrug resistance gene oprM hybridized with genomic DNA from all 20 serotypes of Pseudomonas aeruginosa and from all 34 environmental and clinical isolates tested, indicating that the MexA-MexB-OprM multidrug efflux system is highly conserved in this organism. The oprM probe also hybridized with genomic DNA from Pseudomonas aureofaciens, Pseudomonas chlor...

The MexAB-OprM drug efflux pump is central to multidrug resistance of Pseudomonas aeruginosa. The ability of the tripartite protein to confer drug resistance on the pathogen is crucially dependent on the presence of all three proteins of the complex. However, the role of each protein in the formation of the intact functional complex is not well understood. One of the key questions relates to th...