What are the mechanisms of antibiotic resistance used by Pseudomonas aeruginosa and Burkholderia cepacia complex?

Answer 1

Both bacteria use efflux pumps to remove drugs from the cell and enzymatic degradation to detoxify antibiotics.

Answer 2

Some cursory research on both of the bacteria in the question indicates that they are both indeed resistant to antibiotics, and suggest that efflux pumps are a key factor. This leads into the question of what an efflux pump is, how it can be understood in terms of other concepts in microbiology, and precisely how it contributes to bacteria's lowered susceptibility to antibiotic drugs.

On a basic level, an efflux pump is just a mechanism in a cell which moves things, usually toxic or harmful, out of the cell. (ef=out, flux=flow. Efflux pump makes things flow out. Pretty intuitive.) This process involves the expenditure of energy, making efflux pumps facilitators of active transport (a familiar concept, I hope).¹ Harmful materials such as antibiotics, heavy metals, or pollutants bind to a specific site on the efflux pump, and this binding facilitates transport out via changes in protein folding and resulting signaling pathways within the pump (again, these terms should all sound familiar).³ How a cellular mechanism which simply removes harmful substances from the cell contributes to antibiotic resistance should be obvious.

Hopefully this answer got you thinking about how broader mechanisms like signaling pathways and active transport can contribute to a variety of different cellular functions.

Efflux pumps are also found in all sorts of microorganisms in more or less the same recognizable form, suggesting that that they are key to general survival of microorganisms, and did not evolve as a specific adaptation to the pressures of clinical antibiotics, if you want to approach things from an evolutionary angle.²

1:Rhodes KA, Schweizer HP. Antibiotic resistance in Burkholderia species. Drug Resist Updat. 2016;28:82‐90. doi:10.1016/j.drup.2016.07.003

2: Blanco P, Hernando-Amado S, Reales-Calderon JA, Corona F, Lira F, Alcalde-Rico M, Bernardini A, Sanchez MB, Martinez JL. Bacterial Multidrug Efflux Pumps: Much More Than Antibiotic Resistance Determinants. Microorganisms. 2016; 4(1):14. https://doi.org/10.3390/microorganisms4010014

3: https://en.wikipedia.org/wiki/Efflux_(microbiology)