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Streptothricins
Streptothricins are a group of antibiotics in the aminoglycoside class. The first antibiotic in the group was isolated from ''Streptomyces lavendulae'' in 1942. It was later determined to be a mixture of closely-related compounds, and is now known as nourseothricin. Although initial interest was positive because it appeared to be the first broad-spectrum antibiotic, meaning it was effective against both Gram-positive and Gram-negative Gram-negative bacteria are bacteria that, unlike gram-positive bacteria, do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. Their defining characteristic is that their cell envelope consists ... bacteria, it never found clinical use due to toxicity. However, because of the increasing need for new antibiotics due to resistance to existing antibiotics, there is a current interest in developing new drugs based on the chemical scaffold of the streptothricins. References {{reflist Aminoglycos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Aminoglycoside
Aminoglycoside is a medicinal and bacteriologic category of traditional Gram-negative antibacterial medications that inhibit protein synthesis and contain as a portion of the molecule an amino-modified glycoside (sugar). The term can also refer more generally to any organic molecule that contains amino sugar substructures. Aminoglycoside antibiotics display bactericidal activity against Gram-negative aerobes and some anaerobic bacilli where resistance has not yet arisen but generally not against Gram-positive and anaerobic Gram-negative bacteria.ME Levison, MD, 2012, Aminoglycosides, The Merck Manua accessed 22 February 2014. Streptomycin is the first-in-class aminoglycoside antibiotic. It is derived from ''Streptomyces griseus'' and is the earliest modern agent used against tuberculosis. Streptomycin lacks the common 2-deoxystreptamine moiety (image right, below) present in most other members of this class. Other examples of aminoglycosides include the deoxystreptamine-containin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Streptomyces Lavendulae
''Streptomyces lavendulae'' is a species of bacteria from the genus ''Streptomyces''. It is isolated from soils globally and is known for its production of medically useful biologically active metabolites. To see a photo of this organism clichere Description and significance ''Streptomyces lavendulae'' was first isolated from soil in 1916, and has since been isolated from many soils throughout the world. It is characterized by colorless growth with lavender colored aerial mycelium, though white mutants have been observed . The order Actinomycetales is composed of organisms well known for their ability to make a wide range of biologically active metabolites. ''S. lavendulae'' produces many medically useful antibiotics including streptothricin and lavendamycin, although some mutant strains exist without aerial mycelium, which are unable to produce antibiotics. Cell morphology and physiology Actinomycetes are Gram-positive bacteria that resemble fungi in structure with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Nourseothricin
Nourseothricin (NTC) is a member of the streptothricin-class of aminoglycoside antibiotics produced by ''Streptomyces'' species. Chemically, NTC is a mixture of the related compounds streptothricin C, D, E, and F. NTC inhibits protein synthesis by inducing miscoding. It is used as a selection marker for a wide range of organisms including bacteria, yeast, filamentous fungi, and plant cells. It is not known to have adverse side-effects on positively selected cells, a property cardinal to a selection drug. Streptothricin F is effective against highly drug-resistant gram-negative bacteria, including carbapenem-resistant ''E. coli''. NTC can be inactivated by nourseothricin N-acetyl transferase (NAT) from '' Streptomyces noursei'', an enzyme that acetylates the beta-amino group of the beta-lysine residue of NTC. NAT can thus act as an antibiotic resistance Antimicrobial resistance (AMR or AR) occurs when microbes evolve mechanisms that protect them from antimicrobials, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Gram-positive
In bacteriology, gram-positive bacteria are bacteria that give a positive result in the Gram stain test, which is traditionally used to quickly classify bacteria into two broad categories according to their type of cell wall. The Gram stain is used by microbiologists to place bacteria into two main categories, gram-positive (+) and gram-negative bacteria, gram-negative (−). Gram-positive bacteria have a thick layer of peptidoglycan within the cell wall, and gram-negative bacteria have a thin layer of peptidoglycan. Gram-positive bacteria retain the crystal violet stain used in the test, resulting in a purple color when observed through an optical microscope. The thick layer of peptidoglycan in the bacterial cell wall retains the Stain (biology), stain after it has been fixed in place by iodine. During the decolorization step, the decolorizer removes crystal violet from all other cells. Conversely, gram-negative bacteria cannot retain the violet stain after the decolorization ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Gram-negative
Gram-negative bacteria are bacteria that, unlike gram-positive bacteria, do not retain the crystal violet stain used in the Gram staining method of bacterial differentiation. Their defining characteristic is that their cell envelope consists of a thin peptidoglycan cell wall sandwiched between an inner ( cytoplasmic) membrane and an outer membrane. These bacteria are found in all environments that support life on Earth. Within this category, notable species include the model organism '' Escherichia coli'', along with various pathogenic bacteria, such as '' Pseudomonas aeruginosa'', '' Chlamydia trachomatis'', and '' Yersinia pestis''. They pose significant challenges in the medical field due to their outer membrane, which acts as a protective barrier against numerous antibiotics (including penicillin), detergents that would normally damage the inner cell membrane, and the antimicrobial enzyme lysozyme produced by animals as part of their innate immune system. Furthe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
