What Are the Effects of Antibiotics on Bacteria Evolution?

Bacteria are constantly evolving in an attempt to survive, and the use of antibiotics is a key player in their survival game. When bacteria do evolve, they often decrease the effects of antibiotics, making bacterial infections more difficult to treat. This can worsen the severity of many kinds of bacterial infections, such as strep throat, tuberculosis and staph infections. The key to preventing the evolution of superbugs is to know when antibiotics work and to use them under the supervision of a doctor.

History of Antibiotics

Alexander Fleming first found that a type of mold called penicillin prevented the growth of bacteria in 1928. In the 1940s, penicillin became available to the general public. Fleming grew critical of its widespread use, because he had bred resistant bacteria in his lab that avoided the effects of penicillin. Indeed, until the 1950s, penicillin was available without a doctor's prescription. Without guidance, penicillin's effectiveness was greatly reduced as bacteria grew resistant to it.

How Bacteria Evolve

Whenever antibiotics are used, the potential for bacteria evolution exists. Antibiotics kill bacteria or keep them from growing, which helps the body conquer the infection. The bacteria that survive, however, can grow to be resistant to antibiotic treatment. According to the CDC's "Antibiotic Resistance 101," bacteria grow resistant in many different ways. They can learn how to render the antibiotic ineffective, how to pump it out of the bacteria's interior or change the area of the bacteria that the antibiotic attacks. These defenses can easily multiply among bacteria populations, causing many different defenses.

Agriculture and Bacterial Evolution

In modern agriculture, large animal populations live together in a close environment, which can contribute to the spread of disease. To combat this, animals are often given low doses of antibiotics constantly and high doses of antibiotics when ill. This can lead to the evolution of bacteria such as E. coli, which are difficult to treat with antibiotics and can be deadly.

Effects of Human Antibiotic Misuse

Among humans, the misuse of antibiotics has caused the evolution of several bacterial diseases. One of the diseases that has gained the most attention is methicillin-resistant Staphylococcus aureus, or MRSA---a dangerous skin infection that can cause death. Born in hospitals, this staph infection has caused isolated outbreaks in several communities, immune to all but the strongest antibiotic treatment. Antibiotic misuse has also caused evolution in tuberculosis, gonorrhea, malaria and typhoid fever.

Inhibiting Bacterial Evolution

Proper use of antibiotics can help slow the evolution of drug-resistant bacteria. Follow the guidance of your doctor when asking for antibiotics---many respiratory infections, for example, are viral infections that are not helped by antibiotics and can actually contribute to more severe infection. When you are prescribed antibiotics, take the full cycle so that all the bacteria will be killed. Do not take antibiotics without a doctor's diagnosis of bacterial infection. Protect yourself from bacteria in the first place by washing your hands often. Finally, advocate for more appropriate use of antibiotics in animals, as well as safer living conditions for the animals we eat.

References

• Mayo Clinic Fact Sheet on Antibiotic Resistance
• CDC Antibiotic Resistance 101
• Stuart B. Levy; The Antibiotic Paradox; 2007

Resources

• CDC Fact Sheet on MRSA