Chal­lenging the the­ory of the nar­row host range of phages

Viruses that infect bacteria could one day replace antibiotics because they precisely attack only specific pathogens. Researchers at ETH Zurich are now showing that this is not always the case. This new finding is important ...

Study explores how bacteria become drug resistant

Researchers at Vanderbilt University and the University of Arizona have revealed more of the inner-workings of a two-stage "molecular motor" in the cell membrane that enables bacteria to become resistant to drugs.

New vaccine takes aim at koala chlamydia

A world-first nanoparticle vaccine against chlamydia is now safe to use for the thousands of koalas admitted for treatment in wildlife hospitals across Australia, say University of the Sunshine Coast researchers.

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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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