The Genetic Battle Against Infection

Bacteria: According to Taber’s Cyclopedic Medical Dictionary, are one-celled organisms without a true nucleus and belonging to the kingdom Monera.

Sounds simple, primitive and uncomplicated and yet genetic research into the biochemistry of these organisms is proving otherwise.

Information about science and technology is no longer confined to scientific journals. A recent article in The Economist yielded information on the uncanny ability of bacteria to develop antibiotic resistance. We hear much on this topic. It is believed that the overuse and inappropriate use of antibiotics in humans and livestock contribute to this evolutionary resistance. There is also speculation that the widespread use of popular antibiotic soaps and detergents increases the pressure on bacteria to develop resistance.

How do they do this? Let’s consider three methods:

The production of precise resistance enzymes to dangerous chemicals by bacteria. The use of an "efflux" system by bacteria to eject chemicals through the cell membrane. The production of a "biofilm"- a protected layer of bacteria that adheres to soft tissue resulting in infection.

If we hope to win the battle against illness and disease, what can we do to counteract these resistance methods by bacteria?

Genetic researchers in Boston have identified a regulon (a combination of genes whose expression is controlled by one protein) in the bacterium Escherichia coli. This regulon, called Mar, controls E. coli’s antibiotic defense. When E. coli detects a foreign chemical, it produces a protein called MarA which activates the regulon. The Mar regulon initiates the efflux system and flushes the chemical from the bacterium. MarR, Mar repressor protein, is secreted and turns off the regulon when the antibiotic threat is over.

Genetic researchers have also discovered that without MarA, bacteria are unable to layer and create the biofilm that serves to protect the bacteria.

The primary implication of this genetic research is that by inactivating MarA, infections would not form, bacteria would not gain a foothold in the body and the host’s immune system could easily expel the bacteria from the body. Antibiotics could then be used more sparingly and in reduced dosages and bacteria would decelerate their evolutionary resistance patterns.