Diseases, Conditions, Syndromes

New study uncovers weakness in C. diff toxin

A new study, led by researchers from the University of California, Irvine (UCI), uncovers the long-sought-after, three-dimensional structure of a toxin primarily responsible for devastating Clostridium difficile infection ...

Diseases, Conditions, Syndromes

Current antibiotic stewardship program practices characterized

(HealthDay)—Current infection prevention and antibiotic stewardship program practices continue to include a main focus on surveillance for multidrug-resistant organisms, according to a report published online July 17 in ...

Immunology

Home birth may start babies off with health-promoting microbes

For all of human history, babies have been born where their mothers lived—whether in a house, hut or cave. Only in the last century has birth moved out of the home and into the hospital. How has that changed the types of ...

Medical research

Gut microbes may affect the course of ALS

Researchers at the Weizmann Institute of Science have shown in mice that intestinal microbes, collectively termed the gut microbiome, may affect the course of amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's ...

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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