Resistance Mechanisms

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Bacteria have many different mechanisms encoded in their genome to protect themselves from antibiotic-induced destruction. some examples include:[1]

Efflux Pumps

  • Pumps that recognize chemical structures of antibiotics and actively expell the drug from the cell before it causes DNA damage or cellular lysis. May only be able to pump the drug in the space between the bacteria and the outer cell wall.

Drug Target Modifications

  • Genes encode proteins or enzymes to change the site that the antibiotic would bind to so that it cannot attach.

Antibiotic Modifying Enzymes

  • Enzymes that bind to the drug and deactivate it without destroying it.

Modification of Outer Membrane

  • Create a new barrier or decrease the permeability of the outer membrane by increasing the amount of peptidoglycans or other proteins/carbohydrates to thicken the cell wall. This does not allow the drug to passively diffuse across the membrane.

Regulation of Porins

  • Nutrition channels that are modified to take the antibiotic inside of the cell and expel it beyond the outer cell membrane.

Antibiotic Degrading Enzymes

  • Enzymes that target the drug and completely breakdown the antibiotic.

Mimicking Drug Target Sites

  • Proteins with 3D structures similar to the target; one will mimic DNA's shape and the antibiotic will bind to the protein instead of the bacteria's DNA, causing no damage to the bacteria.


  1. Nguyen L, and Thompson CJ. (2006). Foundations of antibiotic resistance in bacterial physiology: The mycobacterial paradigm. TRENDS in Microbiology. 14,304-312.

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