Clinical pharmacology of antibiotics. Modern classification of antibiotics All about antibiotics pharmacology

Antibiotics are a huge group of bactericidal drugs, each of which is characterized by its own spectrum of action, indications for use and the presence of certain consequences

Antibiotics are substances that can inhibit the growth of microorganisms or destroy them. According to the GOST definition, antibiotics include substances of plant, animal or microbial origin. Currently, this definition is somewhat outdated, since it was created great amount synthetic drugs, but it was natural antibiotics that served as the prototype for their creation.

The history of antimicrobial drugs begins in 1928, when A. Fleming first discovered penicillin. This substance was discovered, and not created, since it has always existed in nature. In living nature, it is produced by microscopic fungi of the genus Penicillium, protecting themselves from other microorganisms.

In less than 100 years, more than a hundred different antibacterial drugs have been created. Some of them are already outdated and are not used in treatment, and some are just being introduced into clinical practice.

How do antibiotics work?

We recommend reading:

All antibacterial drugs can be divided into two large groups according to their effect on microorganisms:

bactericidal– directly cause the death of microbes;
bacteriostatic– prevent the proliferation of microorganisms. Unable to grow and reproduce, bacteria are destroyed by the immune system of a sick person.

Antibiotics exert their effects in many ways: some of them interfere with the synthesis nucleic acids microbes; others interfere with the synthesis of bacterial cell walls, others disrupt protein synthesis, and others block the functions of respiratory enzymes.

Antibiotic groups

Despite the diversity of this group of drugs, all of them can be classified into several main types. This classification is based on the chemical structure - drugs from the same group have a similar chemical formula, differing from each other by the presence or absence of certain molecular fragments.

The classification of antibiotics implies the presence of groups:

Penicillin derivatives. This includes all drugs created on the basis of the very first antibiotic. In this group, the following subgroups or generations of penicillin drugs are distinguished:

Natural benzylpenicillin, which is synthesized by fungi, and semi synthetic drugs: methicillin, nafcillin.
Synthetic drugs: carbpenicillin and ticarcillin, which have a wider spectrum of action.
Mecillam and azlocillin, which have even more wide range actions.

Cephalosporins- Closest relatives of penicillins. The very first antibiotic of this group, cefazolin C, is produced by fungi of the genus Cephalosporium. Most drugs in this group have a bactericidal effect, that is, they kill microorganisms. There are several generations of cephalosporins:

I generation: cefazolin, cephalexin, cefradine, etc.
II generation: cefsulodin, cefamandole, cefuroxime.
III generation: cefotaxime, ceftazidime, cefodizime.
IV generation: cefpirom.
V generation: ceftolozane, ceftopibrol.

The differences between the different groups are mainly in their effectiveness - later generations have a greater spectrum of action and are more effective. 1st and 2nd generation cephalosporins are now used extremely rarely in clinical practice, most of them are not even produced.

– drugs with a complex chemical structure that have a bacteriostatic effect on a wide range of microbes. Representatives: azithromycin, rovamycin, josamycin, leucomycin and a number of others. Macrolides are considered one of the safest antibacterial drugs - they can even be used by pregnant women. Azalides and ketolides are varieties of macorlides that have differences in the structure of the active molecules.

Another advantage of this group of drugs is that they are able to penetrate the cells of the human body, which makes them effective in the treatment of intracellular infections:,.

Aminoglycosides. Representatives: gentamicin, amikacin, kanamycin. Effective against a large number of aerobic gram-negative microorganisms. These drugs are considered the most toxic and can lead to quite serious complications. Used to treat genitourinary tract infections.
Tetracyclines. These are mainly semi-synthetic and synthetic drugs, which include: tetracycline, doxycycline, minocycline. Effective against many bacteria. The disadvantage of these drugs is cross-resistance, that is, microorganisms that have developed resistance to one drug will be insensitive to others from this group.
Fluoroquinolones. These are completely synthetic drugs that do not have their natural counterpart. All drugs in this group are divided into first generation (pefloxacin, ciprofloxacin, norfloxacin) and second generation (levofloxacin, moxifloxacin). They are most often used to treat infections of the ENT organs (,) and respiratory tract (,).
Lincosamides. This group includes the natural antibiotic lincomycin and its derivative clindamycin. They have both bacteriostatic and bactericidal effects, the effect depends on the concentration.
Carbapenems. These are some of the most modern antibiotics, acting on a large number of microorganisms. Drugs in this group belong to reserve antibiotics, that is, they are used in the most difficult cases when other drugs are ineffective. Representatives: imipenem, meropenem, ertapenem.
Polymyxins. These are highly specialized drugs used to treat infections caused by. Polymyxins include polymyxin M and B. The disadvantage of these drugs is toxic effects on the nervous system and kidneys.
Antituberculosis drugs. This is a separate group of drugs that have pronounced action on . These include rifampicin, isoniazid and PAS. Other antibiotics are also used to treat tuberculosis, but only if resistance to the drugs mentioned has developed.
Antifungal agents. This group includes drugs used to treat mycoses - fungal infections: amphothirecin B, nystatin, fluconazole.

Methods of using antibiotics

Antibacterial drugs are available in different forms: tablets, powder from which an injection solution is prepared, ointments, drops, spray, syrup, suppositories. The main uses of antibiotics:

Oral- oral administration. You can take the medicine in the form of a tablet, capsule, syrup or powder. The frequency of administration depends on the type of antibiotic, for example, azithromycin is taken once a day, and tetracycline is taken 4 times a day. For each type of antibiotic there are recommendations that indicate when it should be taken - before, during or after meals. The effectiveness of treatment and the severity of side effects depend on this. Antibiotics are sometimes prescribed to young children in syrup form - it is easier for children to drink the liquid than to swallow a tablet or capsule. In addition, the syrup can be sweetened to eliminate the unpleasant or bitter taste of the medicine itself.
Injectable– in the form of intramuscular or intravenous injections. With this method, the drug reaches the site of infection faster and is more active. The disadvantage of this method of administration is that the injection is painful. Injections are used for moderate and severe diseases.

Important:injections should only be given nurse in a clinic or hospital setting! It is strictly not recommended to inject antibiotics at home.

Local– applying ointments or creams directly to the site of infection. This method of drug delivery is mainly used for skin infections - erysipelas, as well as in ophthalmology - for infections of the eye, for example, tetracycline ointment for conjunctivitis.

The route of administration is determined only by the doctor. In this case, many factors are taken into account: the absorption of the drug in the gastrointestinal tract, the condition digestive system in general (for some diseases, the rate of absorption decreases and the effectiveness of treatment decreases). Some drugs can only be administered one way.

When injecting, you need to know what you can use to dissolve the powder. For example, Abactal can only be diluted with glucose, since when sodium chloride is used it is destroyed, which means the treatment will be ineffective.

Antibiotic sensitivity

Any organism sooner or later gets used to the harshest conditions. This statement is also true in relation to microorganisms - in response to prolonged exposure to antibiotics, microbes develop resistance to them. The concept of sensitivity to antibiotics was introduced into medical practice - the effectiveness with which a particular drug affects the pathogen.

Any prescription of antibiotics should be based on knowledge of the sensitivity of the pathogen. Ideally, before prescribing the drug, the doctor should conduct a sensitivity test and prescribe the most effective drug. But the time required to carry out such an analysis is, in the best case, several days, and during this time the infection can lead to the most disastrous result.

Therefore, in case of infection with an unknown pathogen, doctors prescribe drugs empirically - taking into account the most likely pathogen, with knowledge of the epidemiological situation in a particular region and medical institution. For this purpose, broad-spectrum antibiotics are used.

After performing a sensitivity test, the doctor has the opportunity to change the drug to a more effective one. The drug can be replaced if there is no effect from treatment for 3-5 days.

Etiotropic (targeted) prescription of antibiotics is more effective. At the same time, it becomes clear what caused the disease - using bacteriological research, the type of pathogen is established. Then the doctor selects a specific drug to which the microbe does not have resistance (resistance).

Are antibiotics always effective?

Antibiotics only act on bacteria and fungi! Bacteria are considered single-celled microorganisms. There are several thousand species of bacteria, some of which coexist quite normally with humans—more than 20 species of bacteria live in the large intestine. Some bacteria are opportunistic - they cause disease only under certain conditions, for example, when they enter an atypical habitat. For example, very often prostatitis is caused by E. coli, which enters through the ascending route from the rectum.

Note: Antibiotics are absolutely ineffective for viral diseases. Viruses are many times smaller than bacteria, and antibiotics simply do not have a point of application for their ability. That's why antibiotics have no effect on colds, since colds in 99% of cases are caused by viruses.

Antibiotics for coughs and bronchitis may be effective if they are caused by bacteria. Only a doctor can figure out what causes the disease - for this he prescribes blood tests, and, if necessary, an examination of sputum if it comes out.

Important:Prescribing antibiotics to yourself is unacceptable! This will only lead to the fact that some of the pathogens will develop resistance, and next time the disease will be much more difficult to cure.

Of course, antibiotics are effective for - this disease is exclusively bacterial in nature, caused by streptococci or staphylococci. To treat sore throat, the simplest antibiotics are used - penicillin, erythromycin. The most important thing in the treatment of angina is compliance with the frequency of dosing and the duration of treatment - at least 7 days. You should not stop taking the medicine immediately after the onset of the condition, which is usually noted on the 3-4th day. True tonsillitis should not be confused with tonsillitis, which can be of viral origin.

Note: untreated sore throat can cause acute rheumatic fever or!

Pneumonia (pneumonia) can be of both bacterial and viral origin. Bacteria cause pneumonia in 80% of cases, so even when prescribed empirically, antibiotics for pneumonia have good effect. For viral pneumonia, antibiotics do not have a therapeutic effect, although they prevent the bacterial flora from joining the inflammatory process.

Antibiotics and alcohol

Taking alcohol and antibiotics at the same time in a short period of time does not lead to anything good. Some drugs are broken down in the liver, just like alcohol. The presence of antibiotics and alcohol in the blood puts a strong strain on the liver - it simply does not have time to neutralize ethyl alcohol. As a result, the likelihood of developing unpleasant symptoms: nausea, vomiting, intestinal disorders.

Important: a number of drugs interact with alcohol at the chemical level, resulting in a direct decrease in therapeutic effect. These drugs include metronidazole, chloramphenicol, cefoperazone and a number of others. Concomitant use of alcohol and these drugs can not only reduce the therapeutic effect, but also lead to shortness of breath, seizures and death.

Of course, some antibiotics can be taken while drinking alcohol, but why risk your health? It’s better to abstain from alcoholic drinks for a while - course antibacterial therapy rarely exceeds 1.5-2 weeks.

Antibiotics during pregnancy

Pregnant women suffer from infectious diseases no less often than everyone else. But treating pregnant women with antibiotics is very difficult. The fetus grows and develops in the pregnant woman's body - unborn child, very sensitive to many chemicals. The entry of antibiotics into the developing body can provoke the development of fetal malformations, toxic damage to the central nervous system fetus

During the first trimester, it is advisable to avoid the use of antibiotics altogether. In the second and third trimesters, their use is safer, but should also be limited, if possible.

A pregnant woman cannot refuse to prescribe antibiotics for the following diseases:

Pneumonia;
angina;
infected wounds;
specific infections: brucellosis, borelliosis;
sexually transmitted infections: , .

What antibiotics can be prescribed to a pregnant woman?

Penicillin, cephalosporin drugs, erythromycin, and josamycin have almost no effect on the fetus. Penicillin, although it passes through the placenta, does not have a negative effect on the fetus. Cephalosporin and other named drugs penetrate the placenta in extremely low concentrations and are not capable of harming the unborn child.

Conditionally safe drugs include metronidazole, gentamicin and azithromycin. They are prescribed only for health reasons, when the benefit to the woman outweighs the risk to the child. Such situations include severe pneumonia, sepsis, and other severe infections, in which, without antibiotics, a woman can simply die.

Which drugs should not be prescribed during pregnancy?

The following drugs should not be used in pregnant women:

aminoglycosides– can lead to congenital deafness (with the exception of gentamicin);
clarithromycin, roxithromycin– in experiments they had a toxic effect on animal embryos;
fluoroquinolones;
tetracycline– disrupts the formation of the skeletal system and teeth;
chloramphenicol– dangerous for later pregnancy due to inhibition of bone marrow functions in the child.

For some antibacterial drugs there is no data on negative effects on the fetus. This is explained simply - experiments are not carried out on pregnant women to determine the toxicity of drugs. Experiments on animals do not allow us to exclude all negative effects with 100% certainty, since the metabolism of drugs in humans and animals can differ significantly.

Please note that you should also stop taking antibiotics or change your plans for conception. Some drugs have a cumulative effect - they can accumulate in a woman’s body, and for some time after the end of the course of treatment they are gradually metabolized and eliminated. It is recommended to become pregnant no earlier than 2-3 weeks after finishing taking antibiotics.

Consequences of taking antibiotics

The entry of antibiotics into the human body leads not only to the destruction of pathogenic bacteria. Like all foreigners chemicals, antibiotics have a systemic effect - to one degree or another they affect all systems of the body.

There are several groups of side effects of antibiotics:

Allergic reactions

Almost any antibiotic can cause allergies. The severity of the reaction varies: rash on the body, Quincke's edema (angioedema), anaphylactic shock. While an allergic rash is practically harmless, anaphylactic shock can be fatal. The risk of shock is much higher with antibiotic injections, which is why injections should only be done in medical institutions - emergency care can be provided there.

Antibiotics and other antimicrobial drugs that cause cross-allergic reactions:

Toxic reactions

Antibiotics can damage many organs, but the liver is most susceptible to their effects - toxic hepatitis can occur during antibiotic therapy. Certain drugs have a selective toxic effect on other organs: aminoglycosides - on hearing aid(cause deafness); tetracyclines inhibit growth bone tissue in children.

note: The toxicity of a drug usually depends on its dose, but in case of individual intolerance, sometimes smaller doses are sufficient to produce an effect.

Effects on the gastrointestinal tract

When taking certain antibiotics, patients often complain of stomach pain, nausea, vomiting, and stool disorders (diarrhea). These reactions are most often caused by the locally irritating effect of the drugs. The specific effect of antibiotics on intestinal flora leads to functional disorders its activity, which is most often accompanied by diarrhea. This condition is called antibiotic-associated diarrhea, which is popularly known as dysbiosis after antibiotics.

Other side effects

Other side effects include:

immunosuppression;
emergence of antibiotic-resistant strains of microorganisms;
superinfection – a condition in which microbes resistant to a given antibiotic are activated, leading to the emergence of a new disease;
violation of vitamin metabolism - caused by inhibition of the natural flora of the colon, which synthesizes some B vitamins;
Jarisch-Herxheimer bacteriolysis is a reaction that occurs when using bactericidal drugs, when, as a result of the simultaneous death of a large number of bacteria, a large number of toxins are released into the blood. The reaction is clinically similar to shock.

Can antibiotics be used prophylactically?

Self-education in the field of treatment has led to the fact that many patients, especially young mothers, try to prescribe themselves (or their child) an antibiotic at the slightest sign of a cold. Antibiotics do not have preventive action– they treat the cause of the disease, that is, they eliminate microorganisms, and in their absence they only appear side effects drugs.

Exists limited quantity situations when antibiotics are administered before clinical manifestations of infection, in order to prevent it:

surgery– in this case, the antibiotic present in the blood and tissues prevents the development of infection. As a rule, a single dose of the drug administered 30-40 minutes before the intervention is sufficient. Sometimes even after an appendectomy, antibiotics are not injected in the postoperative period. After “clean” surgical operations, antibiotics are not prescribed at all.
major injuries or wounds(open fractures, soil contamination of the wound). In this case, it is absolutely obvious that an infection has entered the wound and it should be “crushed” before it manifests itself;
emergency prevention of syphilis carried out during unprotected sexual contact with a potentially sick person, as well as among health workers who have had the blood of an infected person or other biological fluid come into contact with the mucous membrane;
penicillin can be prescribed to children for the prevention of rheumatic fever, which is a complication of tonsillitis.

Antibiotics for children

The use of antibiotics in children is generally no different from their use in other groups of people. For children small age Pediatricians most often prescribe antibiotics in syrup. This dosage form more convenient to take, unlike injections, completely painless. Older children may be prescribed antibiotics in tablets and capsules. In severe cases, infections progress to parenteral route administration - injections.

Important: main feature in the use of antibiotics in pediatrics lies in dosages - children are prescribed smaller doses, since the drug is calculated in terms of per kilogram of body weight.

Antibiotics are very effective drugs, which at the same time have a large number of side effects. In order to be cured with their help and not harm your body, they should be taken only as prescribed by a doctor.

What types of antibiotics are there? In what cases is taking antibiotics necessary and in what cases is it dangerous? The main rules of antibiotic treatment are explained by pediatrician Dr. Komarovsky:

Gudkov Roman, resuscitator

An antibiotic is an anti-life substance - a drug that is used to treat diseases caused by living agents, usually various pathogenic bacteria.

Antibiotics are divided into many types and groups for a variety of reasons. The classification of antibiotics makes it possible to most effectively determine the scope of application of each type of drug.

1. Depending on the origin.

Natural (natural).
Semi-synthetic - at the initial stage of production, the substance is obtained from natural raw materials, and then the drug continues to be artificially synthesized.
Synthetic.

Strictly speaking, only drugs obtained from natural raw materials are antibiotics. All other medications are called “antibacterial drugs.” IN modern world The term “antibiotic” means all types of drugs that can fight living pathogens.

What are natural antibiotics made from?

from mold fungi;
from actinomycetes;
from bacteria;
from plants (phytoncides);
from tissues of fish and animals.

2. Depending on the impact.

Antibacterial.
Antitumor.
Antifungal.

3. According to the spectrum of impact on a particular number of different microorganisms.

Antibiotics with a narrow spectrum of action.
These drugs are preferable for treatment because they act specifically on certain type(or group) of microorganisms and do not suppress the healthy microflora of the patient’s body.
Antibiotics with a wide spectrum of effects.

4. By the nature of the effect on the bacterial cell.

Bactericidal drugs – destroy pathogens.
Bacteriostatics – stop the growth and reproduction of cells. Subsequently the immune system The body must independently cope with the bacteria remaining inside.

5. By chemical structure.
For those studying antibiotics, classification by chemical structure is decisive, since the structure of the drug determines its role in the treatment of various diseases.

1. Beta-lactam drugs

1. Penicillin is a substance produced by colonies of mold fungi of the Penicillium species. Natural and artificial penicillin derivatives have a bactericidal effect. The substance destroys the cell walls of bacteria, which leads to their death.

Pathogenic bacteria adapt to medications and become resistant to them. The new generation of penicillins is supplemented with tazobactam, sulbactam and clavulanic acid, which protect the drug from destruction inside bacterial cells.

Unfortunately, penicillins are often perceived by the body as an allergen.

Groups penicillin antibiotics:

Penicillins of natural origin are not protected from penicillinase, an enzyme that is produced by modified bacteria and which destroys the antibiotic.
Semi-synthetics – resistant to bacterial enzymes:
biosynthetic penicillin G - benzylpenicillin;
aminopenicillin (amoxicillin, ampicillin, becampicillin);
semisynthetic penicillin (preparations of methicillin, oxacillin, cloxacillin, dicloxacillin, flucloxacillin).

2. Cephalosporin.

Used in the treatment of diseases caused by bacteria resistant to penicillin.

Today, 4 generations of cephalosporins are known.

Cephalexin, cefadroxil, ceporin.
Cefamezin, cefuroxime (Axetil), cefazolin, cefaclor.
Cefotaxime, ceftriaxone, ceftizadime, ceftibuten, cefoperazone.
Cefpirom, cefepime.

Cephalosporins also cause allergic reactions in the body.

Cephalosporins are used during surgical interventions to prevent complications, in the treatment of ENT diseases, gonorrhea and pyelonephritis.

2. Macrolides
They have a bacteriostatic effect - they prevent the growth and division of bacteria. Macrolides act directly on the site of inflammation.
Among modern antibiotics, macrolides are considered the least toxic and cause a minimum of allergic reactions.

Macrolides accumulate in the body and are used in short courses of 1-3 days. They are used in the treatment of inflammation of the internal ENT organs, lungs and bronchi, and infections of the pelvic organs.

Erythromycin, roxithromycin, clarithromycin, azithromycin, azalides and ketolides.

3. Tetracycline

A group of drugs of natural and artificial origin. They have a bacteriostatic effect.

Tetracyclines are used in the treatment of severe infections: brucellosis, anthrax, tularemia, respiratory and urinary tract. The main disadvantage of the drug is that bacteria adapt to it very quickly. Tetracycline is most effective for local application in the form of ointments.

Natural tetracyclines: tetracycline, oxytetracycline.
Semi-sentitic tetracyclines: chlortetrine, doxycycline, metacycline.

4. Aminoglycosides

Aminoglycosides are highly toxic bactericidal drugs active against gram-negative aerobic bacteria.
Aminoglycosides quickly and effectively destroy pathogenic bacteria even with weakened immunity. To start the mechanism of destruction of bacteria, aerobic conditions are required, that is, antibiotics of this group do not “work” in dead tissues and organs with poor blood circulation(cavities, abscesses).

Aminoglycosides are used in the treatment of the following conditions: sepsis, peritonitis, furunculosis, endocarditis, pneumonia, bacterial kidney damage, urinary tract infections, inflammation of the inner ear.

Aminoglycoside drugs: streptomycin, kanamycin, amikacin, gentamicin, neomycin.

5. Levomycetin

A drug with a bacteriostatic mechanism of action on bacterial pathogens diseases. Used to treat serious intestinal infections.

An unpleasant side effect of treatment with chloramphenicol is bone marrow damage, which disrupts the production of blood cells.

6. Fluoroquinolones

Preparations with a wide spectrum of action and a powerful bactericidal effect. The mechanism of action on bacteria is to disrupt DNA synthesis, which leads to their death.

Fluoroquinolones are used for local treatment eyes and ears, due to severe side effects. The drugs affect joints and bones and are contraindicated in the treatment of children and pregnant women.

Fluoroquinolones are used against the following pathogens: gonococcus, shigella, salmonella, cholera, mycoplasma, chlamydia, Pseudomonas aeruginosa, legionella, meningococcus, mycobacterium tuberculosis.

Drugs: levofloxacin, gemifloxacin, sparfloxacin, moxifloxacin.

7. Glycopeptides

Antibiotic mixed type effects on bacteria. It has a bactericidal effect against most species, and a bacteriostatic effect against streptococci, enterococci and staphylococci.

Glycopeptide preparations: teicoplanin (targocid), daptomycin, vancomycin (vankacin, diatracin).

8. Anti-tuberculosis antibiotics
Drugs: ftivazide, metazide, saluzide, ethionamide, protionamide, isoniazid.

9. Antibiotics with antifungal effect
They destroy the membrane structure of fungal cells, causing their death.

10. Anti-leprosy drugs
Used to treat leprosy: solusulfone, diuciphone, diaphenylsulfone.

11. Antitumor drugs – anthracyclines
Doxorubicin, rubomycin, carminomycin, aclarubicin.

12. Lincosamides
According to their own medicinal properties are very close to macrolides, although in terms of chemical composition they are a completely different group of antibiotics.
Drug: delacin S.

13. Antibiotics that are used in medical practice, but do not belong to any of the known classifications.
Fosfomycin, fusidine, rifampicin.

Table of drugs - antibiotics

Classification of antibiotics by groups, the table distributes some types of antibacterial drugs depending on the chemical structure.

Group of drugs	Drugs	Scope of application	Side effects
Penicillin	Penicillin. Aminopenicillin: ampicillin, amoxicillin, becampicillin. Semi-synthetic: methicillin, oxacillin, cloxacillin, dicloxacillin, flucloxacillin.	Antibiotic with a wide spectrum of effects.	Allergic reactions
Cephalosporin	1st generation: Cephalexin, cefadroxil, ceporin. 2: Cefamezin, cefuroxime (Axetil), cefazolin, cefaclor. 3: Cefotaxime, ceftriaxone, ceftizadime, ceftibuten, cefoperazone. 4: Cefpirom, cefepime.	Surgical operations (to prevent complications), ENT diseases, gonorrhea, pyelonephritis.	Allergic reactions
Macrolides	Erythromycin, roxithromycin, clarithromycin, azithromycin, azalides and ketolides.	ENT organs, lungs, bronchi, pelvic infections.	Least toxic, do not cause allergic reactions
Tetracycline	Tetracycline, oxytetracycline, chlortetrine, doxycycline, metacycline.	Brucellosis, anthrax, tularemia, infections of the respiratory and urinary organs.	Quickly addictive
Aminoglycosides	Streptomycin, kanamycin, amikacin, gentamicin, neomycin.	Treatment of sepsis, peritonitis, furunculosis, endocarditis, pneumonia, bacterial kidney damage, urinary tract infections, inflammation of the inner ear.	High toxicity
Fluoroquinolones	Levofloxacin, gemifloxacin, sparfloxacin, moxifloxacin.	Salmonella, gonococcus, cholera, chlamydia, mycoplasma, Pseudomonas aeruginosa, meningococcus, shigella, legionella, mycobacterium tuberculosis.	Affects the musculoskeletal system: joints and bones. Contraindicated for children and pregnant women.
Levomycetin	Levomycetin	Intestinal infections	Bone marrow damage

The main classification of antibacterial drugs is carried out depending on their chemical structure.

Conditions for action of antibiotics 1) A system biologically important for the life of bacteria must respond to exposure low concentrations the drug through a specific point of application (presence of a “target”) 2) The antibiotic must have the ability to penetrate the bacterial cell and act on the point of application; 3) The antibiotic should not be inactivated before it interacts with the biological active system bacteria. T D

Principles of rational prescribing of antibiotics (4-5) General principles 6. Maximum doses until the disease is completely overcome; The preferred method of drug administration is parenteral. Local and inhaled use of antibacterial drugs should be kept to a minimum. 7. Periodic replacement of drugs with newly created or rarely prescribed (reserve) drugs.

Principles of rational prescribing of antibiotics (5-5) General principles 8. Conducting a program of cyclic replacement of antibacterial drugs. 9. Combined use drugs to which resistance develops. 10. One antibacterial drug should not be replaced with another to which cross-resistance exists.

Semi-synthetic: 1. Isoxazolylpenicillins (penicillinase-stable, antistaphylococcal): oxacillin 2. Aminopenicillins: ampicillin, amoxicillin 3. Carboxypenicillins (antipseudomonas): carbenicillin, ticarcillin 4. Ureidopenicillins: azlocillin, piperacillin 5. Inhibitor protected penicillins: amoxicillin/clavulanate, ampicillin/sulbactam Gr "+" Gr "-"

Mechanism of action of β-lactamines The target of action is penicillin-binding proteins of bacteria, which act as enzymes at the final stage of the synthesis of peptidoglycan, a biopolymer that is the main component of the bacterial cell wall. Blocking peptidoglycan synthesis leads to the death of the bacterium. The effect is bactericidal. Peptidoglycan and penicillin-binding proteins are absent in mammals => specific toxicity towards the macroorganism is not typical for -lactams. Specific toxicity towards a macroorganism is not typical for -lactams.">

To overcome the acquired resistance of microorganisms that produce special enzymes - -lactamase (destroying -lactams), irreversible inhibitors of -lactamase have been developed - clavulanic acid (clavulanate), sulbactam, tazobactam. They are used to create combined (inhibitor-protected) penicillins.

Drug interactions (1-2) Penicillins cannot be mixed in the same syringe or in the same infusion system with aminoglycosides due to their physicochemical incompatibility. When ampicillin is combined with allopurinol, the risk of ampicillin rash increases. Use of high doses of benzylpenicillin potassium salt in combination with potassium-sparing diuretics, potassium supplements or ACE inhibitors determines an increased risk of hyperkalemia.

Drug interactions (2-2) Caution is required when combining penicillins active against Pseudomonas aeruginosa with anticoagulants and antiplatelet agents due to the potential risk of increased bleeding. The use of penicillins in combination with sulfonamides should be avoided, as this may weaken their bactericidal effect.

IV generation Parenteral Cefepime, Cefpirome Active against some strains resistant to III generation cephalosporins. Higher resistance to broad and extended spectrum β-lactamases. Indications: treatment of severe nosocomial infections caused by multidrug-resistant flora; infections due to neutropenia.

Drug interactions When combined with aminoglycosides and/or loop diuretics, especially in patients with impaired renal function, the risk of nephrotoxicity may increase. Antacids reduce the absorption of oral cephalosporins in the gastrointestinal tract. There should be intervals of at least 2 hours between doses of these drugs. When cefoperazone is combined with anticoagulants, thrombolytics and antiplatelet agents, the risk of bleeding, especially gastrointestinal bleeding, increases. If you drink alcohol during treatment with cefoperazone, a disulfiram-like reaction may develop.

Lactam antibiotics Carbapenems: imipenem, meropenem Reserve drugs, more resistant to the action of bacterial β-lactamases, more quickly penetrate the outer membrane of gram-negative bacteria, have a wider spectrum of activity and are used for severe infections of various localizations, including nosocomial (nosocomial) infections. Gr "+" Gr "-" Anaerobes

Lactam antibiotics Monobactams: (monocyclic -lactams) aztreonam Reserve drug, narrow spectrum of action, it should be prescribed in combination with drugs active against gram-positive cocci (oxacillin, cephalosporins, lincosamides, vancomycin) and anaerobes (metronidazole) ~ ~ ~ Gr « - » aerobes

Mechanism of action Bactericidal effect, disruption of protein synthesis by ribosomes. Degree antibacterial activity aminoglycosides depends on their concentration. When used together with penicillins or cephalosporins, synergism is observed against gram-negative and gram-positive aerobic microorganisms.

Basics clinical significance aminoglycosides are used in the treatment of nosocomial infections caused by aerobic gram-negative pathogens, as well as infective endocarditis. Streptomycin and kanamycin are used in the treatment of tuberculosis. Neomycin, as the most toxic among aminoglycosides, is used only orally and topically.

Drug interactions Do not mix in the same syringe or infusion system with β-lactam antibiotics or heparin due to physicochemical incompatibility. Increased toxic effects when two aminoglycosides are administered simultaneously or when they are combined with other nephro- and ototoxic drugs: polymyxin B, amphotericin B, ethacrynic acid, furosemide, vancomycin. Strengthening neuromuscular blockade with simultaneous use of inhalation anesthesia, opioid analgesics, magnesium sulfate and transfusion of large amounts of blood with citrate preservatives. Indomethacin, phenylbutazone and other NSAIDs that interfere with renal blood flow slow down the rate of elimination of aminoglycosides.

Group of aminocyclitols (structurally similar to aminoglycosides) Natural: Spectinomycin Mechanism of action Bacteriostatic effect, suppression of protein synthesis by ribosomes of bacterial cells. Narrow spectrum of antimicrobial activity - gonococci, including strains resistant to penicillin

Group of quinolones/fluoroquinolones I generation (non-fluorinated quinolones): 3 acids - nalidixic, oxolinic and pipemidic (pipemidic) narrow spectrum, 2nd line drugs for urinary tract and intestinal infections II generation (fluoroquinolones): lomefloxacin, norfloxacin, ofloxacin, pefloxacin, ciprofloxacin . Gr "-" Gr "+"

Drug interactions (1-4) When used simultaneously with antacids and other drugs containing magnesium, zinc, iron, bismuth ions, the bioavailability of quinolones may decrease due to the formation of non-absorbable chelate complexes. May slow down the elimination of methylxanthines and increase the risk of their toxic effects. With concomitant use of NSAIDs, nitroimidazole derivatives and methylxanthines increases the risk of neurotoxic effects.

Drug interactions (2-4) Quinolones exhibit antagonism with nitrofuran derivatives, so combinations of these drugs should be avoided. First generation quinolones, ciprofloxacin and norfloxacin can interfere with the metabolism of indirect anticoagulants in the liver, which leads to an increase in prothrombin time and the risk of bleeding. With simultaneous use, dose adjustment of the anticoagulant may be necessary.

Drug interactions (3-4) Increase the cardiotoxicity of drugs that prolong the QT interval on the electrocardiogram, as the risk of developing cardiac arrhythmias increases. When prescribed simultaneously with glucocorticoids, the risk of tendon ruptures increases, especially in the elderly.

Drug interactions (4-4) When ciprofloxacin, norfloxacin and pefloxacin are prescribed together with drugs that alkalinize urine (carbonic anhydrase inhibitors, citrates, sodium bicarbonate), the risk of crystalluria and nephrotoxic effects increases. When used simultaneously with azlocillin and cimetidine, due to a decrease in tubular secretion, the elimination of fluoroquinolones slows down and their concentrations in the blood increase.

Group of macrolides 14-membered: Natural - Erythromycin Semi-synthetic - Clarithromycin, Roxithromycin 15-membered (azalides): Semi-synthetic - Azithromycin 16-membered: Natural - Spiramycin, Josamycin, Midecamycin Semi-synthetic - Midecamycin acetate Gr "+"

Mechanism of action Macrolides temporarily stop the reproduction of gram-positive cocci. The effect is due to disruption of protein synthesis by the ribosomes of the microbial cell. As a rule, macrolides have a bacteriostatic effect, but in high concentrations they can act bactericidal against group A beta-hemolytic streptococcus, pneumococcus, and the causative agents of whooping cough and diphtheria. They have moderate immunomodulatory and anti-inflammatory activity. Inhibits cytochrome P-450 in the liver.

Drug interactions (1-2) Macrolides inhibit metabolism and increase the blood concentration of indirect anticoagulants, theophylline, carbamazepine, valproic acid, disopyramide, ergot drugs, cyclosporine. It is dangerous to combine macrolides with terfenadine, astemizole and cisapride due to the risk of developing severe violations heart rate caused by prolongation of the QT interval. Macrolides increase the bioavailability of digoxin when taken orally by reducing its inactivation by intestinal microflora.

Drug interactions (2-2) Antacids reduce the absorption of macrolides, especially azithromycin, from the gastrointestinal tract. Rifampin increases the metabolism of macrolides in the liver and reduces their concentration in the blood. Macrolides should not be combined with lincosamides due to their similar mechanism of action and possible competition. Erythromycin, especially when administered intravenously, can enhance the absorption of alcohol in the gastrointestinal tract and increase its concentration in the blood.

Group of tetracyclines Natural: tetracycline Semi-synthetic: doxycycline Retain clinical significance for chlamydial infections, rickettsiosis, borreliosis and some particularly dangerous infections, severe acne. Mechanism of action They have a bacteriostatic effect, disrupting protein synthesis in the microbial cell. Gr "+" Gr "-"

Drug interactions (1-2) When taken orally simultaneously with antacids containing calcium, aluminum and magnesium, sodium bicarbonate and cholestyramine, their bioavailability may decrease due to the formation of non-absorbable complexes and an increase in the pH of the gastric contents. Therefore, between doses listed drugs and antacids, it is necessary to observe intervals of 1-3 hours. It is not recommended to combine tetracyclines with iron preparations, since this may interfere with their mutual absorption.

Drug interactions (2-2) Carbamazepine, phenytoin and barbiturates increase the hepatic metabolism of doxycycline and reduce its concentration in the blood, which may require dose adjustment this drug or replacing it with tetracycline. When combined with tetracyclines, the reliability of estrogen-containing oral contraceptives may be reduced. Tetracyclines may enhance the effect of indirect anticoagulants due to inhibition of their metabolism in the liver, which requires careful monitoring of prothrombin time.

Group of lincosamides Natural: lincomycin Its semi-synthetic analogue: clindamycin Mechanism of action They have a bacteriostatic effect, which is caused by inhibition of protein synthesis by ribosomes. In high concentrations they can exhibit a bactericidal effect. Narrow spectrum of antimicrobial activity - (gram-positive cocci (as second-line drugs) and non-spore-forming anaerobic flora. Gr "+"

Drug interactions Antagonism with chloramphenicol and macrolides. Respiratory depression may occur when used concomitantly with opioid analgesics, inhaled narcotics or muscle relaxants. Kaolin- and attapulgite-containing antidiarrheal drugs reduce the absorption of lincosamides in the gastrointestinal tract, so intervals of 3-4 hours are necessary between doses of these drugs.

Group of glycopeptides Natural: vancomycin and teicoplanin Mechanism of action They disrupt the synthesis of the bacterial cell wall. They have a bactericidal effect, but are bacteriostatic against enterococci, some streptococci and coagulase-negative staphylococci. Drugs of choice for infections caused by MRSA, as well as enterococci resistant to ampicillin and aminoglycosides Gr “+”

Drug interactions When used simultaneously with local anesthetics the risk of developing hyperemia and other symptoms of a histamine reaction increases. Aminoglycosides, amphotericin B, polymyxin B, cyclosporine, loop diuretics increase the risk of neurotoxic effects of glycopeptides. Aminoglycosides and ethacrynic acid increase the risk of ototoxicity from glycopeptides.

Group of polymyxins Polymyxin B - parenteral Polymyxin M - oral Mechanism of action They have a bactericidal effect, which is associated with a violation of the integrity of the cytoplasmic membrane of the microbial cell. Narrow spectrum of activity, high toxicity. Polymyxin B is a reserve drug used in the treatment of Pseudomonas aeruginosa infection, Polymyxin M is used for gastrointestinal infections. Gr "-"

Group of rifamycins Natural: rifamycin SV, rifamycin S Semi-synthetic: rifampicin, rifabutin Mechanism of action Bactericidal effect, specific inhibitors of RNA synthesis. Wide range of activities. Rifampicin is a first-line anti-tuberculosis drug, Rifabutin is a second-line anti-tuberculosis drug. Gr « -» Gr « +»

Drug interactions Rifampicin is an inducer of microsomal enzymes of the cytochrome P-450 system; accelerates the metabolism of many drugs: indirect anticoagulants, oral contraceptives, glucocorticoids, oral antidiabetic agents; digitoxin, quinidine, cyclosporine, chloramphenicol, doxycycline, ketoconazole, itraconazole, fluconazole. Pyrazinamide reduces the plasma concentration of rifampicin as a result of its effect on the hepatic or renal clearance of the latter.

Chloramphenicol Natural: Chloramphenicol (chloramphenicol) Mechanism of action Bacteriostatic effect, due to disruption of protein synthesis by ribosomes. In high concentrations it has a bactericidal effect against pneumococcus, meningococcus and H.influenzae. It is used as a second-line drug in the treatment of meningitis, rickettsiosis, salmonellosis and anaerobic infections.

Drug interactions Antagonist of macrolides and lincosamides. Reduces the effectiveness of iron supplements, folic acid and vitamin B 12 by weakening their stimulating effect on hematopoiesis. Inhibitor of microsomal liver enzymes, enhances the effects of oral antidiabetic drugs, phenytoin, warfarin. Inducers of microsomal liver enzymes (rifampicin, phenobarbital and phenytoin) reduce the concentration of chloramphenicol in the blood serum.

Content

Human body every day is attacked by many microbes that try to settle and develop due to internal resources bodies. The immune system usually copes with them, but sometimes the resistance of microorganisms is high and you have to take medications to fight them. There are different groups of antibiotics that have a certain spectrum of action and belong to different generations, but all types of this drug effectively kill pathological microorganisms. Like all powerful medications, this drug has its side effects.

What is an antibiotic

This is a group of drugs that have the ability to block protein synthesis and thereby inhibit the reproduction and growth of living cells. All types of antibiotics are used to treat infectious processes which are caused by different strains of bacteria: staphylococcus, streptococcus, meningococcus. The drug was first developed in 1928 by Alexander Fleming. Antibiotics of certain groups are prescribed for the treatment of oncological pathologies in the composition combination chemotherapy. In modern terminology, this type of medication is often called antibacterial drugs.

Classification of antibiotics by mechanism of action

The first drugs of this type were medications based on penicillin. There is a classification of antibiotics according to groups and mechanism of action. Some of the drugs have a narrow focus, others have a broad spectrum of action. This parameter determines how much the medicine will affect a person’s health (both positively and negatively). Medicines help cope with or reduce the mortality rate of such serious diseases:

sepsis;
gangrene;
meningitis;
pneumonia;
syphilis.

Bactericidal

This is one of the types from the classification of antimicrobial agents according to pharmacological action. Bactericidal antibiotics are medicinal product, which cause lysis, death of microorganisms. The medication inhibits membrane synthesis and suppresses the production of DNA components. The following groups of antibiotics have these properties:

carbapenems;
penicillins;
fluoroquinolones;
glycopeptides;
monobactams;
fosfomycin.

Bacteriostatic

The action of this group of medications is aimed at inhibiting the synthesis of proteins by microbial cells, which prevents them from further multiplying and developing. The effect of the drug results in a limitation further development pathological process. This effect is typical for the following groups of antibiotics:

lincosamines;
macrolides;
aminoglycosides.

Classification of antibiotics by chemical composition

The main division of drugs is based on their chemical structure. Each of them is based on different active substance. This division helps to fight specifically against a specific type of microbe or to have a broad spectrum of action on a large number of varieties. This prevents bacteria from developing resistance (resistance, immunity) to a specific type of medication. The main types of antibiotics are described below.

Penicillins

This is the very first group that was created by man. Antibiotics of the penicillin group (penicillium) have a wide range of effects on microorganisms. Within the group there is an additional division into:

natural penicillin - produced by fungi in normal conditions(phenoxymethylpenicillin, benzylpenicillin);
semisynthetic penicillins are more resistant to penicillinases, which significantly expands the spectrum of action of the antibiotic (methicillin, oxacillin medications);
extended action – preparations of ampicillin, amoxicillin;
medicines with a wide spectrum of action - azlocillin, mezlocillin.

In order to reduce bacterial resistance to this type of antibiotics, penicillinase inhibitors are added: sulbactam, tazobactam, clavulanic acid. Vivid examples of such medications are: Tazocin, Augmentin, Tazrobida. Medicines are prescribed for the following pathologies:

respiratory system infections: pneumonia, sinusitis, bronchitis, laryngitis, pharyngitis;
genitourinary: urethritis, cystitis, gonorrhea, prostatitis;
digestive: dysentery, cholecystitis;
syphilis.

Cephalosporins

The bactericidal property of this group has a wide spectrum of action. The following generations of cephalosporins are distinguished:

I-e, drugs cefradine, cephalexin, cefazolin;
II, products with cefaclor, cefuroxime, cefoxitin, cefotiam;
III, medications ceftazidime, cefotaxime, cefoperazone, ceftriaxone, cefodizime;
IV, products with cefpirome, cefepime;
V-e, medications fetobiprole, ceftaroline, fetolosan.

Exists most of antibacterial medications of this group are only in the form of injections, so they are used more often in clinics. Cephalosporins are the most popular type of antibiotics for inpatient treatment. This class of antibacterial agents is prescribed for:

pyelonephritis;
generalization of infection;
inflammation of soft tissues, bones;
meningitis;
pneumonia;
lymphangitis.

Macrolides

Natural. They were synthesized for the first time in the 60s of the 20th century, these include spiramycin, erythromycin, midecamycin, and josamycin.
Prodrugs, the active form is taken after metabolism, for example, troleandomycin.
Semi-synthetic. These are clarithromycin, telithromycin, azithromycin, dirithromycin.

Tetracyclines

This species was created in the second half of the 20th century. Antibiotics of the tetracycline group have an antimicrobial effect against a large number of strains of microbial flora. At high concentration a bactericidal effect is manifested. A feature of tetracyclines is their ability to accumulate in tooth enamel and bone tissue. This helps in the treatment of chronic osteomyelitis, but also disrupts skeletal development in young children. This group It is prohibited for use by pregnant girls and children under 12 years of age. These antibacterial medications are represented by the following drugs:

Oxytetracycline;
Tigecycline;
Doxycycline;
Minocycline.

Contraindications include hypersensitivity to components, chronic liver pathologies, porphyria. Indications for use are the following pathologies:

Lyme disease;
intestinal pathologies;
leptospirosis;
brucellosis;
gonococcal infections;
rickettsiosis;
trachoma;
actinomycosis;
tularemia.

Aminoglycosides

The active use of this series of medications is carried out in the treatment of infections caused by gram-negative flora. Antibiotics have a bactericidal effect. The drugs show high efficiency, which is not related to the indicator of the patient’s immune activity, making these medications indispensable for weakening of the immune system and neutropenia. The following generations of these antibacterial agents exist:

The drugs kanamycin, neomycin, chloramphenicol, streptomycin belong to the first generation.
The second includes products with gentamicin and tobramycin.
The third includes amikacin drugs.
The fourth generation is represented by isepamycin.

The following pathologies are indications for the use of this group of medications.

(meronem), doripenem (doriprex), ertapenem (invanz).

Aminoglycosides

II generation – gentamicin, tobramycin, netilmicin.

Quinolones/fluoroquinolones:

I generation – non-fluorinated quinolones (nalidixic acid, oxolinic acid, pipemidic acid)

II generation - Gram-negative fluoroquinolones (lomefloxacin, norfloxacin, ofloxacin, pefloxacin,).

III generation - respiratory fluoroquinolones (sparfloxacin).

IV generation – respiratory antianaerobic fluoroquinolones (moxifloxacin, gemifloxacin).

Distribution of macrolides by chemical structure

Goals of antibacterial therapy– therapeutic effectiveness; preventing pathogen resistance to antimicrobial agents(limiting the selection of resistant strains of microorganisms).

Before prescribing an antibiotic, it is necessary to take a material (smear, secretion, etc.) and send it for bacteriological examination. Taking into account the results of bacteriological examination of the material and assessment of the sensitivity of the isolated pathogen to antibiotics, targeted antibiotic therapy.

Empirical antibiotic prescription has to be carried out according to the expected microflora, since the doctor will receive the results of the bacteriological examination no earlier than in 4–5 days. When choosing an antibacterial drug, the tropism of the microorganism to tissues is taken into account. For example, erysipelas most often caused by streptococci; soft tissues, purulent mastitis, – staphylococci; pneumonia – pneumococci, mycoplasmas; - Escherichia coli.

Having decided the question of the suspected pathogen, the doctor selects an antibacterial drug to which the microorganism should be sensitive. Currently, it is recommended to give preference to drugs with a narrow spectrum of action, which allows limiting the formation of microflora resistance.

Semi-synthetic penicillins with a narrow spectrum of action (antistaphylococcal, penicillinase-stable): the spectrum of activity is similar to that of natural penicillins, but the drug is resistant to penicillinases and is active against penicillin-resistant strains of Staphylococcus aureus (PRSA). No effect on methicillin-resistant staphylococci (MRSA).

III. Semi-synthetic broad-spectrum penicillins (aminopenicillins): and, unlike natural and antistaphylococcal penicillins, act on some aerobic Gram-negative enterobacteria (Escherichia coli, Salmonella, Shigella) and Haemophilus influenzae (). active against Helicobacter pylory.

However, strains of staphylococci that produce beta-lactamases are not sensitive to aminopenicillins, so a new generation of penicillin antibiotics has emerged, combined with beta-lactamase inhibitors (clavulanic acid, sulbactam, tazobactam).

Inhibitor-protected penicillins: amoxicillin/clavulanic acid acts on all microorganisms sensitive to amoxicillin. The drug has higher antistaphylococcal activity (including penicillin-resistant strains of Staphylococcus aureus), and is active against gram-negative bacteria that produce beta-lactamases (for example, Escherichia coli, Proteus).

Ampicillin/sulbactam has an antimicrobial spectrum similar to amoxicillin/clavulanic acid.

Spectrum of antimicrobial action of cephalosporins

I generation – active against Gram-positive flora (streptococci, staphylococci, including PRSA). MRSA, as well as most strains of enterobacteria and anaerobes, are resistant to the drugs.

II generation: spectrum of action is close to 1st generation cephalosporins.

IV generation - compared to III generation cephalosporins, they are more active against Gram-positive cocci and have antipseudomonal activity. acts on streptococci, staphylococci (except MRSA), meningococci, N. influenzae. Enterobacteriaceae (Escherichia coli, Proteus, Klebsiella, Serration, etc.) are highly sensitive to the drug.

Antimicrobial spectrum of carbapenems

Compared to other beta-lactam antibiotics, they have a wider spectrum of antimicrobial activity, including strains of Gram-negative bacteria (Escherichia coli, Klebsiella, Serration, Enterobacter, Citrobacter, etc.), and anaerobes. The drugs act on staphylococci (except MRSA), streptococci, most penicillin-resistant pneumococci, meningococci, gonococci.

A distinctive feature of ertapenem is the lack of activity against Pseudomonas aeruginosa.

Antimicrobial spectrum of quinolones/fluoroquinolones

The first generation (quinolones) acts predominantly on Gram-negative bacteria of the Enterobacteriaceae family.

Second generation fluoroquinolones have a much wider spectrum; they are active against a number of Gram-positive aerobic bacteria (Staphylococcus spp., Streptococcus spp., etc.), most Gram-negative bacteria and intracellular pathogens (Chlamydia spp., Mycoplasma spp.).

Fluoroquinolones of the III and IV generations (respiratory) are highly active against pneumococci and staphylococci, and are also more active than drugs of the II generation against intracellular pathogens.

Spectrum of antimicrobial action of aminoglycosides

Aminoglycosides of the II and III generations are characterized by bactericidal activity against Gram-negative microorganisms of the Enterobacteriaceae family (E. coli, Proteus spp., Klebsiella spp., Enterobacter spp., Serratia spp., etc.) as well as non-fermenting Gram-negative rods (P. aeruginosa ). active against staphylococci, except MRSA. and act on M. tuberculosis. not active against pneumococci and anaerobes (Clostridium spp., etc.).

Spectrum of antimicrobial action of macrolides

– in the lungs, bronchial secretions (macrolides, penicillins, respiratory fluoroquinolones, cephalosporins);

– in the central nervous system (cephalosporins of the III and IV generations);

– in the skin, mucous membranes (penicillins, macrolides, lincosamides), etc.

The dosage regimen of antibiotics largely depends on the rate of their elimination, which consists of the processes of hepatic biotransformation and renal excretion. The transformation of macrolides (and others) occurs in the liver, but the main route of excretion of antibiotics is the kidneys, through which penicillins, cephalosporins, fluoroquinolones, carbapenems, and aminoglycosides are excreted.

In case of renal failure, adjustment of the dosage regimen of the above drugs is required, taking into account the value of serum creatinine. If endogenous creatinine clearance is less than 80 ml/min (stage I–II renal failure), it is necessary to reduce the single dose and/or frequency of administration of the following antibiotics - aminoglycosides, first generation cephalosporins, tetracyclines (except doxycycline), glycopeptides, carbapenems. If endogenous creatinine clearance is less than 30 ml/min (stage III renal failure), there is a danger of using antibiotics such as aminopenicillins, cephalosporins, and carbapenems.

In clinical practice, an individual dosage regimen for drugs in patients with chronic renal failure (CRF) is carried out after calculating creatinine clearance (CC). Special formulas have been developed that can be used to calculate CC in adult patients, taking into account the patient’s body weight, age and gender. The most famous and generally accepted is the Cockroft formula:

for men

for women the indicator is additionally multiplied by 0.85

The given formulas are applicable to patients with normal or reduced body weight. In obese patients, CC is calculated using the same formulas, but instead of the actual weight, the proper body weight is used.

For example : Patient A ., 76 years old, admitted to the department intensive care with a diagnosis: Community-acquired bilateral lower lobe polysegmental, severe course. DN III. Due to severe clinical condition, the patient was prescribed Meronem. To calculate the dosage regimen, age (76 years), weight (64 kg), serum creatinine (180 µmol/ml) were taken into account -

Taking into account the information presented in the reference literature, a dosage regimen for the drug “meronem” was determined for a patient with impaired renal elimination function - with a CC value of 28.4 ml/min, an individual dosage regimen of the drug 1 g every 12 hours, 2 times a day .

Dosage regimen for the drug “meropenem” (reference book “Vidal”, 2007)

It should be emphasized that the rate of renal excretion of antibiotics may decrease with dehydration, chronic circulatory failure, hypotension, and urinary retention. Due to the fact that in case of renal failure, the period of elimination of drugs excreted by the kidneys is prolonged, the daily dose of the drug is reduced either by reducing the single dose or by increasing the interval between doses. On the contrary, in clinical practice, in case of renal failure, individual drugs (, ) do not require dose adjustment due to their dual route of elimination from the body (renal and hepatic clearance), which ensures their elimination.

To maintain the average therapeutic concentration of antibiotics, it is important to take into account their pharmacokinetic interaction with drugs from other groups. For example, antacids reduce the absorption of tetracyclines; affect the rate of excretion of aminoglycosides, which are excreted unchanged by the kidneys.

Evaluation of the effectiveness and side effects of antibacterial therapy

Evaluation of the effectiveness of antibacterial therapy includes clinical and laboratory-instrumental indicators:

dynamics of symptoms of the disease (decrease and decrease in the severity of signs of organ damage);
dynamics of activity indicators inflammatory process (clinical analysis blood, urine analysis, etc.);
dynamics of bacteriological indicators (culture of pathological material with determination of flora sensitivity to antibiotics).

If there is no positive dynamics, a change of drug is necessary after 3 days. This issue is resolved taking into account the spectrum of action of the previously prescribed antibiotic and the most likely pathogen, which could not be influenced by previously carried out pharmacotherapy.

Side effects of antibacterial therapy

Allergic reactions (a cross-allergic reaction between beta-lactam antibiotics of the penicillin group, cephalosporins, carbapenems is possible).
Direct toxic effect of drugs on organs:

a) defeat gastrointestinal tract(, , erosions and ulcers). In particular, taking tetracyclines can lead to stomatitis and colitis, lincomycin - to pseudomembranous colitis, amoxicillin/clavulanate (amoxiclav) - to antibiotic-associated diarrhea;

b) neurotoxicity (polyneuritis), the possibility of slowing down neuromuscular conduction is characteristic of aminoglycosides and lincosamides, convulsive syndrome can be caused by the carbapenem antibiotic thienam;

c) nephrotoxicity (glomerulonephritis, renal failure) occurs when using aminoglycosides, glycopeptides, cephalosporins;

d) hepatotoxicity with the appearance of cholestasis is characteristic of macrolides and lincosamides;

e) hematotoxicity (inhibition of leukopoiesis, thrombocytopoiesis, erythropoiesis, hemolytic reactions, hemocoagulation disorders) is more common with the use of tetracyclines and chloramphenicol;

f) cardiotoxicity (prolongation of the QT interval) – while taking fluoroquinolones;

g) damage to bone tissue (growth retardation), disruption of the structure of tooth enamel is caused by tetracyclines;

h) adverse effect on growth cartilage tissue provide fluoroquinolones;

i) photosensitivity () is observed during therapy with fluoroquinolones and tetracyclines.

Most antibacterial drugs that affect Gram-negative flora cause disruption of the intestinal microflora with the development of dysbiosis.
Candidiasis local and/or systemic.

Possible errors when carrying out antibacterial therapy:

unreasonable prescription of an antibiotic (viral infection; the isolated microorganism does not cause the disease);
drug resistance (or secondary);
incorrect dosage regimen of drugs (late treatment, use of low doses, non-compliance with the frequency of administration, interruption of the course of therapy);
incorrectly chosen route of administration;
ignorance of pharmacokinetic parameters (danger of accumulation);
insufficient consideration of concomitant pathology (implementation of undesirable effects);
irrational combination of several antibiotics;
irrational choice of drug in patients with an underlying condition (pregnancy, lactation);
incompatibility (pharmacodynamic, pharmacokinetic and physicochemical) of the antibiotic with other medicines when administered simultaneously.