Medications

Why does tuberculosis find a 65-year-old drug so hard to resist?

Since its discovery in 1954, there have been almost no recorded cases of tuberculosis becoming resistant to the antibiotic drug D-cycloserine (DCS) in patients. With resistance to many other drugs on the rise, a team of ...

Diseases, Conditions, Syndromes

Tracing travelers' typhoid to get an early warning of emerging threats

Salmonella enterica serovar Typhi causes more than 20 million cases of typhoid fever each year, and disproportionately infects children in low and middle income countries. Now, in a paper published in PLOS Neglected Tropical ...

Medical research

Deadly infections on the increase: Urgent need for new antibiotics

Globally, the number of deaths from infections is on the rise as more bacteria become resistant to antibiotics. New classes are desperately needed. A promising resistance inhibitor is now being developed by the research group ...

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Antibiotic

In common usage, an antibiotic (from the Ancient Greek: ἀντί – anti, "against", and βίος – bios, "life") is a substance or compound that kills bacteria or inhibits their growth. Antibiotics belong to the broader group of antimicrobial compounds, used to treat infections caused by microorganisms, including fungi and protozoa.

The term "antibiotic" was coined by Selman Waksman in 1942 to describe any substance produced by a microorganism that is antagonistic to the growth of other microorganisms in high dilution. This original definition excluded naturally occurring substances that kill bacteria but are not produced by microorganisms (such as gastric juice and hydrogen peroxide) and also excluded synthetic antibacterial compounds such as the sulfonamides. Many antibiotics are relatively small molecules with a molecular weight less than 2000 Da.[citations needed]

With advances in medicinal chemistry, most antibiotics are now semisynthetic—modified chemically from original compounds found in nature, as is the case with beta-lactams (which include the penicillins, produced by fungi in the genus Penicillium, the cephalosporins, and the carbapenems). Some antibiotics are still produced and isolated from living organisms, such as the aminoglycosides, and others have been created through purely synthetic means: the sulfonamides, the quinolones, and the oxazolidinones. In addition to this origin-based classification into natural, semisynthetic, and synthetic, antibiotics may be divided into two broad groups according to their effect on microorganisms: those that kill bacteria are bactericidal agents, while those that only impair bacterial growth are known as bacteriostatic agents.

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