Aminoglycosides are a group of antibiotics that are effective against certain types of bacteria. They include amikacin, gentamicin, kanamycin, neomycin, netilmicin, paromomycin, streptomycin, tobramycin and apramycin. Aminoglycosides that are derived from Streptomyces genus are named with the suffix -mycin, while those which are derived from Micromonospora are named with the suffix -micin. This nomenclature system is not specific for aminoglycosides, as vancomycin is a glycopeptide antibiotic and erythromycin, clarithromycin, azithromycin are macrolides - all of which differ in their mechanism of actions. An antibiotic is a drug that kills or slows the growth of bacteria. ... Phyla/Divisions Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Omnibacteria Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria (singular, bacterium) are a major group of living organisms. ... Amikacin is an aminoglycoside antibiotic used to treat different types of bacterial infections. ... Gentamicin is an aminoglycoside antibiotic, and can treat many types of bacterial infections, particularly Gram-negative infection. ... This article does not cite any references or sources. ... Neomycin is an aminoglycoside antibiotic that is found in many topical medications such as creams, ointments and eyedrops. ... Netilmicin is an aminoglycoside antibiotic. ... Paromomycin sulfate (brand name Humatin) is a drug that fights intestinal amoeba infection, or amebiasis. ... Streptomycin is an antibiotic drug, the first of a class of drugs called aminoglycosides to be discovered, and was the first antibiotic remedy for tuberculosis. ... Tobramycin sulfate is an aminoglycoside antibiotic used to treat various types of bacterial infections, particularly Gram-negative infections. ... Apramycin (also Nebramycin II) is an aminoglycoside antibiotic. ... Streptomyces is a genus of Actinobacteria. ... For other uses, see Genus (disambiguation). ... Species see text Micromonospora is a genus of bacteria of the family Micromonosporaceae. ... Crystal structure of a short peptide L-Lys-D-Ala-D-Ala (bacterial cell wall precursor, in green) bound to vancomycin (blue) through hydrogen bonds. ... This page may meet Wikipedias criteria for speedy deletion. ...

Mechanism of action

Aminoglycosides work by binding to the bacterial 30S ribosomal subunit (some work by binding to the 50S subunit), inhibiting the translocation of the peptidyl-tRNA from the A-site to the P-site and also causing misreading of mRNA, leaving the bacterium unable to synthesize proteins vital to its growth. However, their exact mechanism of action is not fully known. There is no significant relationship between the dose administered and the resultant plasma level in blood. TDM, therapeutic drug monitoring, is necessary to obtain the correct dose. These agents exhibit a post-antibiotic effect in which there is no or very little drug levels detectable in blood, but there still seems to be inhibition of bacterial re-growth. This is due to strong, irreversible binding to the ribosome, and remains intracellular long after plasma levels drop. This allows a prolonged dosage interval. Depending on their concentration they act as bacteriostatic or bacteriocidial agents. Centuries: 1st century BC - 1st century - 2nd century Decades: 20s BC - 10s BC - 0s - 10s - 20s - 30s - 40s - 50s - 60s - 70s - 80s 30 31 32 33 34 35 36 37 38 39 Sometimes the 30s is used as shorthand for the 1930s, the 1830s, or other such decades in various... Figure 1: Ribosome structure indicating small subunit (A) and large subunit (B). ... Centuries: 1st century BC - 1st century - 2nd century Decades: 0s - 10s - 20s - 30s - 40s - 50s - 60s - 70s - 80s - 90s - 100s 50 51 52 53 54 55 56 57 58 59 Sometimes the 50s is used as shorthand for the 1950s, the 1850s, or other such decades in various centuries Events... Bacteriostatic antibiotics hamper the growth of bacteria by interfering with bacterial: Protein production, DNA replication, Cellular metabolism. ... A bacteriocide or bactericide is a substance that kills bacteria and, preferably, nothing else. ...

Blocks initiation of protein synthesis, blocks translation, and incorporates incorrect amino acid into chain.

Spectrum of activity

Aminoglycosides are useful primarily in infections involving aerobic, gram-negative bacteria, such as Pseudomonas, Acinetobacter, and Enterobacter. In addition, some Mycobacteria, including the bacteria that cause tuberculosis, are susceptible to aminoglycosides. The most frequent use of aminoglycosides is empiric therapy for serious infections such as septicemia, complicated intraabdominal infections, complicated urinary tract infections, and nosocomial respiratory tract infections. Usually, once cultures of the causal organism are grown and their susceptibilities tested, aminoglycosides are discontinued in favor of less toxic antibiotics. Aerobic and anaerobic bacteria can be identified by growning them in liquid culture: 1: Obligate aerobic bacteria gather at the top of the test tube in order to absorb maximal amount of oxygen. ... Bacteria that are Gram-negative are not stained dark blue or violet by Gram staining, in contrast to Gram-positive bacteria. ... Type species Pseudomonas aeruginosa Species group P. aeruginosa P. alcaligenes P. anguilliseptica P. argentinensis P. borbori P. citronellolis P. flavescens P. mendocina P. nitroreducens P. oleovorans P. pseudoalcaligenes P. resinovorans P. straminea group P. aurantiaca P. aureofaciens P. chlororaphis P. fragi P. lundensis P. taetrolens group P. antarctica P. azotoformans... Species A. baumannii A. lwoffii etc. ... Species etc. ... Species see text Mycobacterium is the a genus of actinobacteria, given its own family, the Mycobacteriaceae. ... Tuberculosis (abbreviated as TB for tubercle bacillus or Tuberculosis) is a common and deadly infectious disease caused by mycobacteria, mainly Mycobacterium tuberculosis. ...

Streptomycin was the first effective drug in the treatment of tuberculosis, though the role of aminoglycosides such as streptomycin and amikacin has been eclipsed (because of their toxicity and inconvenient route of administration) except for multiple drug resistant strains.

Infections caused by gram-positive bacteria can also be treated with aminoglycosides, but other types of antibiotics are more potent and less damaging to the host. In the past the aminoglycosides have been used in conjunction with beta-lactam antibiotics in streptococcal infections for their synergistic effects, particularly in endocarditis. One of the most frequent combinations is ampicillin (a beta-lactam, or penicillin-related antibiotic) and gentamicin. Often, hospital staff refer to this combination as "amp and gent" or more recently called "pen and gent" for penicillin and gentamicin. Gram-positive bacteria are those that are stained dark blue or violet by gram staining, in contrast to gram-negative bacteria, which are not affected by the stain. ... Endocarditis is an inflammation of the inner layer of the heart, the endocardium. ...

Aminoglycosides are mostly ineffective against anaerobic bacteria, fungi and viruses.

Experimentation with Aminoglycosides as a treatment in Cystic Fibrosis has shown some promising results. In about 10% of Cystic Fibrosis cases, it is caused by a mutation in the genetic code that leads to early termination of elongation in protein synthesis, leading to a truncated and non-functioning CFTR (Cystic Fibrosis Transmembrane Conductance Regulator) protein. It is believed that Gentamicin distorts the structure of the ribosome-RNA complex, leading to a mis-reading of the codon. The misreading causes the ribosome to "skip" over the stop sequence, leading to normal elongation and production of the CFTR protein. The treatment is still experimental, but promising.

Toxicity

The toxicity of these agents are dose-related, and therefore every individual can get these side effects provided the dose is sufficiently high enough. Because of their potential for ototoxicity and nephrotoxicity (kidney toxicity), aminoglycosides are administered in doses based on body weight. Vestibular damage, hearing loss and tinnitus are irreversible, so care must be taken not to achieve a sufficiently high dose. Concomitant administration of a cephalosporin may lead to increased risk of nephrotoxicity while administration with a loop diuretic increases the risk of ototoxicity. Blood drug levels and creatinine are monitored during the course of therapy, as there is a highly variable dose to plasma level in blood. Serum creatinine measurements are used to estimate how well the kidneys are functioning and as a marker for kidney damage caused by these drugs. They may react with and prolong the actions of neuromuscular agents. Impaired renal function necessitates a reduced dose.^{[citation needed]} Ototoxicity is damage of the ear (oto), specifically the cochlea or auditory nerve and sometimes the vestibulum, by a toxin (often medication). ... Nephrotoxicity is a poisonous effect of some substances, both toxins and medication, on the kidney. ... The kidneys are the organs that filter wastes (such as urea) from the blood and excrete them, along with water, as urine. ... // Toxic and Intoxicated redirect here – toxic has other uses, which can be found at Toxicity (disambiguation); for the state of being intoxicated by alcohol see Drunkenness. ... The cephalosporins, are a class of β-lactam antibiotics. ... Loop diuretics are diuretics that act on the ascending loop of Henle in the kidney. ... Creatinine is a breakdown product of creatine phosphate in muscle, and is usually produced at a fairly constant rate by the body (depending on muscle mass). ...

Routes of administration

Since they are not absorbed from the gut, they are administered intravenously and intramuscularly. Some are used in topical preparations for wounds. Oral administration can be used for gut decontamination (e.g. in hepatic encephalopathy). An intravenous drip in a hospital Intravenous therapy or IV therapy is the administration of liquid substances directly into a vein. ... Intramuscular injection is an injection of a substance directly into a muscle. ...

External links

• MedlinePlus drug information - Aminoglycosides (Systemic)