Signs of selection in the stomach

Helicobacter pylori, a globally distributed gastric bacterium, is genetically highly adaptable. Microbiologists at LMU have now characterized its population structure in individual patients, demonstrating an important role ...

The extraordinary powers of bacteria visualized in real time

The global spread of antibiotic resistance is a major public health issue and a priority for international microbiology research. In a paper to be published in the journal Science, a team led by Christian Lesterlin, Inserm ...

Imported spices and frozen vegetables tested for 'superbugs'

A University of Saskatchewan research team has found that some food imported to Saskatoon from certain Asian countries has tested positive for "superbugs"—strains of antibiotic-resistant bacteria—but immediate health ...

Directed evolution opens door to new antibiotics

In the ongoing arms race with humans and their antibiotics on one side, and bacteria with their ability to evolve defenses to antibiotics on the other, humans have enlisted a new ally—other bacteria.

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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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