Antibiotic resistance happens when an antibiotic loses its ability to effectively kill or control the growth of bacteria. The bacteria become resistant and continue to spread and multiply in the presence of an antibiotic.
Resistance to antibiotics is a natural phenomenon. When you use an antibiotic, the bacteria which can resist that antibiotic have a bigger chance of survival compared to those which are susceptible.
An antibiotic kills susceptible bacteria, resulting in a selective pressure for the survival of bacteria’s resistant strains. However, there are some bacteria which can produce and use antibiotics against other bacteria, resulting in resistance without human interaction. This may lead to a low-level of natural selection for resistance to antibiotics. On the other hand, the higher-levels of antibiotic-resistant bacteria are resulted by the overuse and abuse of antibiotics.
Antibiotics can be purchased without a doctor’s prescription over the internet and in some countries. People usually use antibiotics unnecessarily in order to treat viral illnesses, such as flu and cold. There are some bacteria which are naturally resistant to some types of antibiotics. However, bacteria can also become resistant by acquiring resistance from another bacterium or by a genetic mutation.
Rare, spontaneous changes of the genetic material of bacteria, mutations are thought to occur in about 1 to 1 million to 1 in 1o millions cells. Different types of resistance are yielded by different genetic mutations. Some mutations eliminate the cell target which the antibiotic attacks, while other mutations enable the bacteria to produce potent chemicals which inactivate antibiotics.
Others mechanisms export the antibiotic back outside so the antibiotic never reaches the target, and other close up the entry ports which allow antibiotics into the cell. There are several ways in which bacteria can acquire the resistance of antibiotic genes from other bacteria. By undergoing a simple mating process which is called conjugation, bacteria are able to shift genetic material from one bacterium to another, including genes encoding resistance to antibiotics.
Another mechanism for passing resistance traits between bacteria are viruses. The traits of resistance from one bacterium are packaged into the virus. The resistance traits are then injected into any new bacteria which is attacked by the virus. In addition, bacteria can also acquire free DNA from their environment. Any bacteria which acquire resistance genes have the ability to resist one or more antibiotics, whether by genetic exchange with other bacteria or by spontaneous mutation.
Bacteria can become resistant to many different families of antibiotics, because they can collect multiple resistance traits over time. Genetically, the resistance of antibiotic spreads through bacteria populations both horizontally, when bacteria exchange or share sections of genetic material with other bacteria, and vertically, when new generations inherit antibiotic resistance genes. Environmentally, the resistance of antibiotic spreads as bacteria move from one place to another.
Bacteria can travel via wind, water and airplane. Also, people can pass the resistance bacteria to others. This can be done, for example, by contact with unwashed hands or by coughing. The antibiotic resistance traits can be lost. However, this reverse process happens more slowly. The bacterial population can revert to a bacteria population which responds to antibiotics, if the selective pressure which is applied by the presence of an antibiotic is removed.