This may be possible as tolC from Ty21a strains unable to dock with AcrAB
in acute strain.
The acrAB gene operates within the complex MAR system.
Paratek projects that products related to its work on the mar operon and now the acrAB locus, could be used to enhance the potency of currently marketed antibiotics, such as fluoroquinolones, penicillins and cephalosporins.
Cheng, "First emergence of acrAB
and oqxAB mediated tigecycline resistance in clinical isolates of Klebsiella pneumoniae predating the use of tigecycline in a Chinese hospital," PLoS One, vol.
To assess the activity of AcrAB efflux pumps, minimal inhibitory concentrations (MICs) of ciprofloxacin were performed by microtiter plate method alone and in the presence of different putative efflux pump inhibitors (EPIs): carbonyl cyanide m-chlorophenylhydrazone (CCCP), norepinephrine (NOR) and trimethoprim (TMP) (Sigma, St.
However, no synergy was seen between trimethoprim and ciprofloxacin for strains of Salmonella Typhimurium in which acrA, acrB, acrAB or tolC were inactivated.
These are Algieba ([gamma] Leonis), Cor Caroli ([alpha] Canum Venaticorum), and Acrab
According to our previous study, Real Time PCR showed an increased expression level of OqxAB and AcrAB
efflux pumps in fluoroquinolone-resistant isolates in comparison with the sensitive ones (data not shown).
marA, (6) soxRS, (7) rob, (8) and ramA (9) have been found to activate acrAB
transcription by binding to the marbox sequence characterized in its promoter.
Additional resistance mechanisms, such as decreased cell envelope permeability (loss of outer membrane porins or alterations of the lipopolysaccharide), decreased cellular accumulation of quinolones involving the major multidrug active efflux pump (AcrAB
), or the presence of integrons, can also be responsible for fluoroquinolones resistance and resistance to a wide range of antimicrobial agents (31,35-39).
This type of resistance generally involves multiple mutations in the genes encoding the quinolone target enzymes, gyrase and topoisomerase IV (2), and mutations in regulatory systems (marORAB ) or soxRS ) or drug efflux systems (AcrAB
Selection of multiple antibiotic-resistant (mar) mutants of Escherichia coli by using the disinfectant pine oil: roles of the mar and acrAB