What are antibiotics?

Antibiotics - agents of microbial, animal or plant origin, selectively inhibit the viability of microorganisms.

Most antibiotics applied in clinical practice, derived from actinomycetes (ray fungi). Antibiotics are very effective in the treatment of many infectious diseases caused by bacteria, fungi, protozoa, spirochetes, rickettsia, large viruses. The doctrine of antibiotics is closely linked with the problem of antagonism between different microbial species.

Currently, 2000 is described in more antibiotics, partially or fully studied the structure 600 from which a number of synthesized. However, in practice, use of about 50 drugs, as many antibiotics are toxic to humans. Antibiotics are classified depending on the origin, chemical structure, spectrum. For clinical practice important indicator to the use of a drug is a range of activities - the circle of micro-organisms for which the active antibiotic.

There are narrow spectrum antibiotics (penicillin), a broad-spectrum (tetracyclines), intermediate spectrum (macrolides). Moreover, there are products which possess antifungal activity (polyene antibiotics), antitumor activity (actinomycin, mitomycins et al.).

On the mechanism of action of antibiotics can be divided into:

1) violates the formation and function of membranes of the microorganism,

2) violates the synthesis of ribonucleic and deoxyribonucleic acids and protein microbial cells.

Therapeutic value of antibiotics (if any sensitivity to the causative agent) depends on the nature of absorption of the antibiotic and drug distribution in the body, and on paths and the dynamics of its removal from the body.

Of great importance in the creation of the maximum concentration in a particular organ and tissue has a method of administration.
When the use of antibiotics can result in various side effects. Of particular note is the emergence of multiple antibiotic resistant forms of microorganisms, which is associated with excessive and often unjustified use of antibiotics. Resistance of microorganisms to antibiotics develops selectively. An important factor is the emergence of microbes resistant to multiple antibiotics (polyresistance, cross-resistance).

In diseases caused by resistant forms of microorganisms are recommended new drugs, as well as a combination treatment of several antibiotics.
Antibiotics Production is carried out biological, synthetic and semi-synthetic routes. Great attention is paid to the production of antibiotics by semisynthetic. So I managed to get a large number of derivatives of penicillin, differing from it by their pharmacological and antibacterial properties.

Antibiotics (from the Greek of anti -. Against and bios - life) - products of microbial metabolism, especially of lower plants that have the ability to suppress the vital activity of other microorganisms or development of cells of some cancers.

In a broader sense, it called antibiotics and antimicrobial agents which are part of the higher plants or animals. The relatively small number of natural antibiotics can have a specific effect in a sick body, ie. E. Serve as drugs. In this sense, very similar to antibiotics synthesized chemotherapeutic agents, differing from them only in the way of preparation.

Classification.

Antibiotics can be classified not only by their producing microorganisms, but also the direction of action and the chemical structure.
For example, usually distinguished anticancer antibiotics, antivirals, antibiotics active against pathogenic fungi against Mycobacterium tuberculosis, etc.

According to the chemical structure of antibiotics are divided into the following groups:..

1) A. acyclic structure, of which the most important polyene antifungals such as nystatin,

2) A. alicyclic structure,

3) the tetracyclines,

4) A. an aromatic structure,

5) chloramphenicol (chloramphenicol),

6) quinones,

7) oxygen-containing heterocyclic compounds, of which the most important griseofulvin active against dermatophytes,

8) the macrolides, which include erythromycin, oleandomycin, magnamitsin et al.,

9) and streptomycin streptomitsinopodobnye A., including neomycin mitserin, monomitsin, kanamycin, paromomycin et al.,

10) nitrogen-containing heterocyclic compounds, including cycloserine and one of the first anti-a .- puromycin,

11) penicillins,

12) polypeptides and proteins, which include gramicidin, bacitracin, polymyxins, lysozyme, kolimitsiny, grizein, albomitsin et al.,

13) depsipeptides,

14) actinomycins having antineoplastic properties generally, and

15) streptothricins.

Getting.

Higher plants produce a large number of antibiotic substances, but because of the low efficiency in the infected organism, they are not used in the clinic, with the exception of a few occupying a special position of quinine.

The antibiotic substances of animal origin - lysozyme, and ekmolin erythrite - are of limited use. Major producers of antibiotics used in medicine are microorganisms - bacteria and microscopic fungi.
Isolation of microorganisms these antibiotics based on the phenomenon of antagonism microbes.

For natural antibiotic industrial way it should accumulate in the culture medium in large quantities. For this purpose, as a rule, it requires preliminary work on the selection of the most active strains - producers and on drawing up the nutrient medium, which would ensure the highest production of antibiotics. Upon completion of the fermentation the culture liquid is separated from the mycelium and purified. Production of some antibiotics relatively simple structure (eg, chloramphenicol and cycloserine) is also carried out by chemical synthesis.

The action on the microbial cell antibiotics may be bacteriostatic or bactericidal. The nature of the action of antibiotics on the microbial cell depends not only on the nature of the substance but also on the state of the cell, which is determined by its hereditary characteristics and physiological activity. Hereditarily fixed increase in microbial resistance to A. is called drug resistance and is the result of changes in the genetic characteristics of a microorganism as a result of its interaction with A. The ability to quickly produce especially drug-resistant staphylococci are different.