Antibiotics

Antibiotics are medicines that act against bacteria by killing them or stopping their growth. In everyday clinical use, the term usually refers to antibacterial drugs; the broader term antimicrobial also covers medicines directed against other kinds of microbes, including fungi and parasites. Antibiotics are used to prevent or treat particular bacterial infections, but the choice of drug depends on which bacteria are involved and whether they are susceptible to it.

Antibiotics target processes or structures that bacteria need to survive and reproduce. Some, including penicillins, interfere with construction of the bacterial cell wall. Other classes disrupt bacterial protein production, DNA or RNA processes, or the production of folate needed to make nucleic acids. Depending on the medicine and organism, a drug may kill bacteria or inhibit their growth. Because drugs differ in their targets and the bacteria they affect, antibiotics are not interchangeable.

Antibiotics can be critical in treating bacterial diseases, including severe and life-threatening infections. They do not work against viruses: taking them for a cold, influenza, or another viral infection will not cure the illness. Some illnesses can have similar symptoms but different causes, and not every infection caused by bacteria necessarily needs antibiotic treatment. Antibiotics can also cause side effects, ranging from nausea, diarrhea, or rash to serious allergic reactions. Decisions about whether an antibiotic is appropriate belong with a qualified health professional.

In 1928, Scottish bacteriologist Alexander Fleming noticed that a Penicillium mold contaminating a culture plate inhibited nearby bacteria. The substance became known as penicillin. In the late 1930s and early 1940s, Howard Florey, Ernst Chain, and colleagues at Oxford worked to purify, test, and develop penicillin for medical use; wartime research and industrial production helped make it available on a much larger scale. Fleming, Chain, and Florey shared the 1945 Nobel Prize in Physiology or Medicine for the discovery of penicillin and its curative effect in various infectious diseases. The development of other antibiotic classes followed, greatly expanding treatment options.

Antibiotic resistance is a property of bacteria, not a person's body. Within a bacterial population, organisms carrying traits that reduce a drug's effect may survive exposure and reproduce; resistance traits can also move between bacteria. When susceptible competitors are suppressed, resistant bacteria can become more common. Unnecessary or inappropriate antibiotic use adds selection pressure and can contribute to this process. Resistant infections may be harder, and sometimes impossible, to treat with the medicines that previously worked.

The effectiveness of antibiotics depends on using them when they are likely to help and selecting a medicine that fits the infection. Public-health guidance emphasizes taking antibiotics only when needed and following the directions of the prescribing health professional. They should not be used for viral illnesses or shared with another person. Responsible use reduces avoidable side effects and helps slow the spread of resistance, while preserving these medicines for infections that require them.