by Joshua Horn

Created on: November 14, 2009

Antibacterial soaps kill bacteria, but it is clear that they can play a role in developing bacteria that are immune to antibacterial chemicals. As these resistant strains grow, eventually our antibacterial soaps will be useless. But why does antibacterial soap cause this resistance? To answer this question, we have to look at how resistance is developed and the role that antibacterial soaps can play in this.

How is Occurs

There are two primary ways that antibiotic resistance is gained. The first involves simple genetic mutations. Single point mutations in the genome allow genes to mutate. If the mutation is negative, and it usually is, the bacterium will die. But if the mutation is neutral or even beneficial, the bacteria will grow and thrive. If this mutation affects a particular protein or pathway related to antibiotic resistance, it may make the bacteria more capable of surviving exposure to antibiotics.

The other method for gaining antibiotic resistance is through lateral gene transfer. Lateral gene transfer, or horizontal gene transfer, involves the sharing of genetic material between bacteria. If one bacterium has antibiotic resistance, it could spread that resistance to neighboring bacteria through lateral gene transfer. Also, when genetic material is transferred, it often recombines or mutates. This is similar to the way simple genetic mutations can create resistance.

The Problem With Antibacterial Soaps

The specific problem with antibacterial soaps involves its role in creating a new form of natural selection. Every time antibacterial soap is used, all the susceptible bacteria are killed. But most antibacterial products can only claim a 99.9% effectiveness. These surviving bacteria usually have some form of mutation that granted them the ability to survive the antibiotic. This bacteria reproduce and eventually you have a new colony full of bacteria with some resistance.

These bacteria mutate and propagate just as before, but this time when you hit them with the antibacterial product, fewer die. The survivors are resistant, grow and reproduce. This cycle continues until you have effectively built a strain of bacteria that are extremely resilient in the face of the particular antibacterial you are using. Because the antibacterial chemicals are no longer effective, these bacteria can grow and spread, causing infection.

This is the basic mechanism behind infections in hospitals as well. The overuse of a variety of antibiotics has developed strains with multiple forms of resistance. These spread and soon people have infections that cannot be killed with even a variety of antibiotics.

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