Antibiotics (from other Greek, ἀντί "against" + βίος "life") are substances of natural, semisynthetic or synthetic origin that suppress the growth of living cells, most often prokaryotic or protozoans.
Classification A huge variety of antibiotics and their effects on the human body was the reason for the classification and separation of antibiotics into groups. By the nature of the effect on the bacterial cell, antibiotics can be divided into two groups:
-Bacteriostatic (bacteria remain alive, but not able to reproduce), -Bactericidal (bacteria die, and then are excreted from the body). Classification of the chemical structure, which is widely used in the medical environment, consists of the following groups:
Beta-lactam antibiotics, divided into three subgroups: Penicillins - are produced by the colonies of the mold fungus Penicillinum; Cephalosporins - have a similar structure with penicillins. Used in relation to penicillin-resistant bacteria. Carbapenems - the structure is more resistant to lactamases than penicillins and cephalosporins, which greatly expands the spectrum of action. Macrolides are antibiotics with complex cyclic structure. The action is bacteriostatic. Tetracyclines - are used to treat infections of the respiratory and urinary tract, treatment of severe infections such as anthrax, tularemia, brucellosis. The action is bacteriostatic. Aminoglycosides - have a high toxicity. Used to treat severe infections such as blood or peritonitis infection. The action is bactericidal. Levomycetins - Use is limited due to the increased risk of serious complications - damage to the bone marrow that produces blood cells. The action is bacteriostatic. Glycopeptide antibiotics disrupt the synthesis of the bacterial cell wall. They have a bactericidal effect, but against enterococci, some streptococci and staphylococci act bacteriostatically. Lincosamides have a bacteriostatic effect, which is due to inhibition of protein synthesis by ribosomes. In high concentrations against highly sensitive microorganisms may exhibit a bactericidal effect. Anti-TB drugs - Isoniazid, Ftivazid, Salusid, Metazide, Ethionamide, Prothionamide. Antibiotics of different groups - Rifamycin, Ristomycin sulfate, Fusidine-sodium, Polymyxinum M sulfate, Polymyxin B sulfate, Gramicidin, Heliomycin. Antifungal antibiotics - destroy the membrane of the fungal cells and cause their death. Action - the lytic. Gradually replaced by highly effective synthetic antifungal drugs. Anti-leprosy drugs - Diphenylsulfone, Solesulfone, Dyuzifon. Beta-lactam antibiotics Beta-lactam antibiotics (β-lactam antibiotics, β-lactams) are a group of antibiotics that combine the presence of a β-lactam ring in the structure. To beta-lactams are subgroups of penicillins, cephalosporins, carbapenems and monobactams. The similarity of the chemical structure predetermines the same mechanism of action of all β-lactams (disruption of bacterial cell wall synthesis), as well as cross-allergy to them in some patients.
Penicillins
Penicillins are antimicrobials belonging to the class of β-lactam antibiotics. The ancestor of penicillins is benzylpenicillin (penicillin G, or just penicillin), used in clinical practice since the early 1940s.
Cephalosporins
Cephalosporins is a class of β-lactam antibiotics, whose chemical structure is based on 7-aminocephalosporanic acid (7-ACS). The main features of cephalosporins in comparison with penicillins are their greater resistance to β-lactamases - enzymes produced by microorganisms. As it turned out, the first antibiotics - cephalosporins, having high antibacterial activity, do not possess complete resistance to β-lactamases. Being resistant to plasmid lactamases, they are destroyed by chromosomal lactamases, which are produced by gram-negative bacteria. To increase the stability of cephalosporins, expand the spectrum of antimicrobial activity, improve pharmacokinetic parameters, their numerous semi-synthetic derivatives were synthesized.
Carbapenems
Carbapenems (English carbapenems) are a class of β-lactam antibiotics, with a wide range of actions, having a structure that determines their high resistance to beta-lactamases. Not resistant against a new type of beta-lactamase NDM1
Macrolides
Macrolides are a group of drugs, mostly antibiotics, the basis of the chemical structure of which is a macrocyclic 14- or 16-membered lactone ring to which one or more carbohydrate residues are attached. The effect of macrolides is due to a violation of protein synthesis on the ribosomes of microorganisms. Macrolides belong to the class of polyketides, compounds of natural origin. Macrolides are among the least toxic antibiotics.
Also macrolides include:
azalides, which are a 15-membered macrocyclic structure obtained by incorporating a nitrogen atom into a 14-membered lactone ring between 9 and 10 carbon atoms; Ketolides are 14-membered macrolides, in which a keto group is attached to the lactone ring at the 3-carbon atom. In addition, the group of macrolides nominally includes the drug tacrolimus related to immunosuppressants, the chemical structure of which is the 23-membered lactone ring.
Tetracyclines
Tetracyclines - a group of antibiotics belonging to the class of polyketides, close in chemical structure and biological properties. Representatives of this family are characterized by a common spectrum and mechanism of antimicrobial action, full cross-resistance, close pharmacological characteristics. The differences relate to certain physico-chemical properties, the degree of antibacterial effect, the characteristics of absorption, distribution, metabolism in the macroorganism, and tolerability.
Aminoglycosides
Aminoglycosides - a group of antibiotics, the common in the chemical structure of which is the presence in the molecule of aminosugar, connected by a glycosidic bond with an aminocyclic ring. As for the chemical structure, aminoglycosides are also close to spectinomycin, an aminocyclitol antibiotic. The main clinical significance of aminoglycosides lies in their activity against aerobic gram-negative bacteria.
Lincosamides
Lincosamides - a group of antibiotics, which includes the natural antibiotic lincomycin and its semisynthetic analog clindamycin. Possess bacteriostatic or bactericidal properties, depending on the concentration in the body and the sensitivity of microorganisms. The effect is due to the suppression of protein synthesis in bacterial cells by binding the 30S subunit of the ribosomal membrane. Lincosamides are resistant to the action of hydrochloric acid of gastric juice. After oral administration, they are rapidly absorbed. Used for infections caused by gram-positive cocci (mainly as second-line drugs) and non-spore-forming anaerobic flora. They are usually combined with antibiotics that affect the gram-negative flora (eg, aminoglycosides).
Chloramphenicol
Chloramphenicol (levomycetin) is a broad-spectrum antibiotic. Colorless crystals of a very bitter taste. Applied for the treatment of typhoid fever, dysentery and other diseases. Toxic. CAS registration number: 56-75-7. Racemic form - sintomycin
Glycopeptide antibiotics
Glycopeptide antibiotics - a class of antibiotics, consists of glycosylated cyclic or polycyclic non-ribosomal peptides. This class of antibiotics inhibits the synthesis of cell walls in sensitive microorganisms, inhibiting the synthesis of peptidoglycans.
Polymyxin
Polymyxins are a group of bactericidal antibiotics that have a narrow spectrum of activity against gram-negative flora. The main clinical significance is the activity of polymyxins against P. aeruginosa. By chemical nature, these are polyene compounds that include residues of polypeptides. In normal doses, the drugs of this group act bacteriostatically, in high concentrations - have a bactericidal effect. Of the drugs are mainly used polymyxin B and polymyxin M. They have a pronounced nephro- and neurotoxicity.
Sulfanilamide antibacterial preparations
Sulfanilamides (Latin sulfanilamide) is a group of chemicals derived from para-aminobenzenesulfonamide-sulfanilic acid amide (para-aminobenzenesulfonic acid). Many of these substances have been used since the middle of the twentieth century as antibacterial drugs. para-Aminobenzenesulfamide - the simplest compound of the class - is also called white streptocide and has been used in medicine to this day. A somewhat more complex sulfanilamide structure, Pronozil (red streptocide) was the first drug of this group and in general the world's first synthetic antibacterial drug.
Quinolones
Quinolones are a group of antibacterial drugs, also including fluoroquinolones. The first drugs of this group, primarily nalidixic acid, have been used for many years only with infections of the urinary tract. But after receiving fluoroquinolones it became obvious that they can be of great importance in the treatment of systemic bacterial infections. In recent years, this is the most dynamically developing group of antibiotics.
Fluoroquinolones (English fluoroquinolones) - a group of drugs with a pronounced antimicrobial activity, widely used in medicine as broad-spectrum antibiotics. According to the breadth of the spectrum of antimicrobial action, activity and indications for use, they are really close to antibiotics, but differ from them in chemical structure and origin. (Antibiotics are products of natural origin or similar synthetic analogues of such, while fluoroquinolones do not have a natural analogue). Fluoroquinolones are divided into the first (pefloxacin, ofloxacin, ciprofloxacin, lomefloxacin, norfloxacin) and the second generation (levofloxacin, sparfloxacin, moxifloxacin). Of the preparations of the group of fluoroquinolones, lomefloxacin, ofloxacin, ciprofloxacin, levofloxacin, sparfloxacin and moxifloxacin are on the List of vital and essential drugs.
Nitrofuran derivatives
Nitrofurans are a group of antibacterial agents. Nitrofurans are sensitive to gram-positive and gram-negative bacteria, as well as chlamydia and some protozoa (Trichomonas, Giardia). Normally, Nitrofurans act bacterially on microorganisms, but in high doses they can have a bactericidal effect. Nitrofurans rarely develop resistance to microflora.
Anti-TB drugs
Antituberculosis drugs - preparations active against the stick Koch (Latin Mycobactérium tuberculósis). According to the international anatomical-therapeutic-chemical classification ("ATC", English ATC), the code is J04A.
By activity, antituberculous drugs are divided into three groups:
the most effective (isoniazid, rifampicin), moderately effective (streptomycin, kanamycin, amikacin, ethambutol, pyrazinamide, ofloxacin, ciprofloxacin, ethionamide, prothionamide, capreomycin, cycloserine), low effective (PAS, thioacetazone)
Antifungal antibiotics Nystatin - an antifungal agent of the polyene series, is used in the therapy of candidiasis. First isolated from Streptomyces noursei in 1950. Amphotericin B is a drug, an antifungal drug. Polyene macrocyclic antibiotic with antifungal activity. Streptomyces nodosus is produced. It has a fungicidal or fungistatic effect depending on the concentration in biological fluids and the sensitivity of the pathogen. It binds to sterols (ergosterols) located in the cell membrane of the fungus and is embedded in the membrane, forming a low-selective ion channel with very high conductivity. As a result, the intracellular components exit into the extracellular space and lysis of the fungus. It is active against Candida spp., Cryptococcus neoformans, Aspergillus spp. and other fungi. Does not affect bacteria, rickettsia, viruses.
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