Knowing how to determine a viral or bacterial infection using a blood test, you can avoid mistakes in choosing medicines. This will not only make the therapy effective, but also prevent Negative consequences from the use of drugs such as antibiotics and sulfonamides.

A blood test will help in making a diagnosis

For decryption leukocyte formula you need to know the normal content of blood cells, as well as changes that are caused by various microorganisms. Despite the presence of exceptions to the rules, there are general patterns in changes in its composition.

Changes due to bacterial infection

When pathogenic bacteria multiply, the following occurs:

• increase in the number of leukocytes and neutrophils (in in rare cases do not exceed the norm);
• a slight decrease in the number of lymphocytes (sometimes normal);
• increase in ESR.

The presence of immature forms of granulocytes in the blood, which include metamyelocytes and myelocytes, indicates a severe form of pathology.

Changes due to viral infection

It is possible to assume that the body is infected with viruses if the picture of blood parameters during the analysis is as follows:

• the number of leukocytes is slightly reduced or normal;
• increase in the number of lymphocytes and monocytes;
• decrease in the number of neutrophils;
• slight increase in ESR.

When infected with the hepatitis C, B or HIV virus, no changes in blood test parameters are observed, since the body does not perceive these microorganisms as a foreign protein and does not produce antigens or interferon. For precise setting Diagnosis involves reactions using specific markers.

Specific markers will show the nature of the disease

The shift in the leukocyte formula and the erythrocyte sedimentation rate may change with prolonged chronic infection when organ cells are destroyed.

Exceptions to the rules

The penetration of tuberculosis and syphilis bacteria into the human body is accompanied by a slight increase in the number of lymphocytes and monocytes, which is typical for infections of viral etiology. This also happens with the development of fungal microflora.

A significant increase in ESR indicates the presence malignant tumors, heart attacks, dysfunction endocrine glands, kidneys, liver, autoimmune diseases.

A strong increase or decrease in the level of white blood cells indicates leukemia or leukopenia. In this case, bacterial and viral infections do not play a role, since these pathologies can be caused by long-term antiviral or chemotherapy, radiation exposure and other factors.

Leukocyte formula

Before determining a viral or bacterial infection, you should understand the concept of “leukocyte formula,” which in the medical literature is called a leukogram.

This term denotes the ratio different forms leukocytes in relation to each other, expressed as a percentage. Its determination occurs by counting cells in a smear under a microscope.

For healthy person characterized by the presence in the peripheral bloodstream of mature segmented neutrophils and a small number of young band forms. The development of severe pathologies can be indicated by the presence of immature granulocytes (metamyelocytes, myelocytes and promyelocytes), which should not normally be present. This occurs when the number of microbes significantly exceeds the number of mature immune cells that do not have time to cope with pathogenic agents.

The detection of young leukocytes in smears and an increase in the number of band forms is called a “shift of the leukocyte formula to the left.”

A liter of blood from a healthy person contains 4.5-9*10⁹ leukocytes. Viral infections do not have a significant effect on this indicator, but bacterial microflora increases it by 2-3 times.

Making a final diagnosis

A blood test is not the only indicator that is taken into account when making a diagnosis, since medical practice There are often cases when viral infections are complicated by the development bacterial microflora. On the background general decline level of immunity there is an increased reproduction of conditionally pathogenic microorganisms, causing development inflammation and pathologies. The doctor draws conclusions and prescribes treatment only after complete clinical examination. Sometimes it is necessary additional conduct studies (radiography, cardiogram, biopsy and others).

VIRUS or BACTERIA: how to tell?

• So, let me remind you that there is a common name “ARD” that describes all infectious diseases of the respiratory tract. They have special cases - viral (ARVI) and bacterial.
• I have already said that in the majority (~95%) the cause of acute respiratory infections is viruses, less often (~5%) - bacteria
• The first symptom of ANY infection is fever. When the temperature rises, the doctor’s primary task is to exclude a bacterial infection (and not to lower the temperature, as parents seem to think).
• The diagnosis is made by a DOCTOR based mainly on EXAMINATION. Other tests should be additional (blood and urine tests, x-rays, streptate tests, bacterial cultures from the hearth, etc.).
• For respiratory viruses, the “favorite” cells are the cells of the respiratory tract: most acute respiratory viral infections proceed in approximately the same way. The most frequent symptoms ARVI is: cough, runny nose, sneezing, fever, hoarseness, sore throat.
• There are no exact signs to differentiate between a viral or bacterial infection, but there are some indirect signs.

What can speak in favor of the virus?

• someone else in the house is sick
• symptoms characteristic of ARVI are noted
• after the temperature drops, the child feels well and is active (runs, plays, etc.)
• the temperature is quite high (38C and above), rises sharply

What should alert you and can speak in favor of bacterial infections?

• no one except the child got sick
• severe intoxication (weakness, lethargy, drowsiness, refusal to eat and drink, photophobia) (influenza is an exception; with influenza, intoxication will also be very pronounced)
• there are some symptoms that are not characteristic of ARVI (this is assessed by the doctor when examining the child)
• against the background of a decrease in temperature, the child continues to be weak
• there are changes in the blood test characteristic of a bacterial infection
• changes in the blood test are not always present, but in most cases. They are assessed by a doctor.

- Among the most common bacterial infections in children are: otitis media, lymphadenitis, abscesses, arthritis, pneumonia, in children >3 years old - also sinusitis (sinusitis, from 5 years old - sphenoiditis, from 7-8 years old - frontal sinusitis)

— These differences must be established by the DOCTOR during the first examination of the child

— The doctor makes a diagnosis that indicates the location infectious process(only in 20% of cases the focus cannot be identified).

1️. The following diseases are usually associated with bacteria:

• pyelonephritis
• adenoiditis
• skin and soft tissue infection
• less often: meningitis, osteomyelitis, arthritis, etc.

2️. The most common causes of viruses are:

• bronchitis and bronchiolitis
• rhinitis and nasopharyngitis
• false croup
• gastroenteritis

PLEASE NOTE: BOTH VIRUSES AND BACTERIA can be caused by:

• pharyngitis, tonsillitis, pneumonia, otitis media, sinusitis, stomatitis, lyphadenitis and other diseases
• There are more than 200 viruses. For a doctor or parent, it does not matter which virus causes the disease. Treatment exists only for the influenza virus, the herpes virus. For other viruses, the tactics are the same and there are no drugs that destroy the virus; therefore, there is no point in treating a “red throat”, runny nose, “cough”, etc. We can alleviate the symptoms of a child’s illness, but this will not affect the cause itself (the virus).
• The likelihood of developing bacterial infections is reduced by hardening, other restorative procedures, as well as vaccination, first of all, against pneumococcus, Haemophilus influenzae, influenza, meningococcus, and other vaccines included in the national calendar.
• If confirmed bacterial infection, then taking an antibiotic is NECESSARY.

Take care of your children!

Candidate of Sciences and mother, pediatrician and neonatologist, Levadnaya Anna Viktorovna

If a child gets sick, it is very important to distinguish a viral infection from a bacterial one in time, because they require different approach in treatment and errors in therapy can be costly. The final diagnosis, of course, remains with the doctor, but parents must have at least basic knowledge in order to be able to provide first aid to their child in a timely manner. first aid. We will tell you how to distinguish a viral infection from a bacterial one in this material.

Main differences

The main difference between a viral disease and a bacterial one lies in the causative agent of the disease itself. Viral diseases are caused by viruses, bacterial - by bacteria. With regard to childhood diseases, especially during the cold season, the most common are viral diseases - influenza, ARVI. The famous pediatrician Evgeny Komarovsky claims that 95% of all cases of childhood morbidity with respiratory and general manifestations(runny nose, cough, fever) are exclusively viral in origin.

• Viruses cannot exist anywhere and anyhow, they are quite capricious in choosing their location. Typically, each viral infection has its own localization, its own site of replication of the causative virus. In case of influenza, the corresponding virus infects at the first stage exclusively the cells of the ciliated epithelium of the upper respiratory tract; in case of hepatitis - only liver cells; rotavirus infection the pathogen is activated exclusively in thin section intestines.
• Bacteria are less fastidious. They begin to multiply where there is already a lesion. When a cut occurs, the wound begins to fester; when bacteria enter the larynx, if the integrity of the mucous membranes is damaged, severe purulent inflammation pharynx and larynx, for example, with bacterial sore throat. The bacterium can spread throughout the body, “settling” where local immunity is reduced.

Knowing the difference and being able to distinguish one from the other is necessary in order to correctly approach the care and treatment of a child. Viral diseases should never, under any circumstances, be treated with antibiotics. Antibacterial drugs are not effective against viruses and only increase the likelihood of developing severe complications.

To treat viral infections, there are drugs - antiviral and immunostimulating. And with a bacterial infection it is impossible to do without antibiotics.

Symptom difference

In order to understand the difference viral disease from bacterial, parents need to carefully monitor their child. The difference is noticeable already at the very initial stage.

• Most viral diseases have an acute onset– the baby’s temperature rises to high levels (38.0-40.0 degrees), he suddenly becomes ill. With the flu, the nose usually remains dry; with other acute respiratory viral infections, one of the first signs is liquid nasal mucus. This condition is described as “running from the nose.”

• Bacterial runny nose(rhinitis) differs in color, consistency and smell. Snot with such a runny nose has a thick consistency, green or dark yellow color, sometimes with blood streaks, bad smell pus. The onset of a bacterial disease is not acute or abrupt. Usually the temperature does not rise immediately, but gradually, but gradually it can reach high values, but more often it is of a low-grade, long-term nature, and the state of health also gradually worsens.
• With a viral infection, the general condition is disrupted literally from the first hours of illness. There are signs of intoxication, muscle and joint pain, severe headache, sometimes - nausea and vomiting due to high fever. At bacterial disease the discomfort zone is usually localized quite clearly. If the bacteria infect the throat, a sore throat is observed; if it gets into the eyes, it is conjunctivitis; if it is in the lungs, it is pneumonia. Bacteria can cause meningitis and severe bronchitis.
• The incubation period also varies. Viral infections develop in the body after infection in a few hours or a couple of days, and bacteria need about 10 days to two weeks to “get comfortable”, multiply in sufficient quantities and begin to secrete a large number of toxins.

• Almost any viral “sore” goes away on its own in 3-6 days in the absence of complications. Bacterial diseases will require some “tinkering”; you usually cannot manage without a course (or even several courses) of antibiotics, and recovery is delayed.
• Among the people, symptoms of acute respiratory viral infections, acute respiratory infections, influenza and bacterial rhinitis or sore throats are very often called the single word “cold”. This is wrong.

A cold is nothing more than a weakening of the child’s immunity, made possible as a result of hypothermia. A cold may well precede a viral or bacterial infection, but is not considered an independent disease. A cold can be distinguished from a virus or bacteria by the absence of fever and acute catarrhal symptoms. The only one reliable way distinguish one from the other, and at the same time find out which viruses or bacteria have infected the child - laboratory diagnostics

. Analysis of blood, urine, throat and nasal swabs is a sufficient basis for laboratory determination of either viral particles and antibodies, or specific bacteria. About what is different viral infection

from bacterial, you can learn from specialists below. Don't know how to distinguish a viral infection from a bacterial one? Then first of all pay attention to whether there is sharp pain in the throat, what is the dynamics of the increase in body temperature. If your throat is sore or sore, but there is no temperature, then you are dealing with a bacterial infection, but a high body temperature without signs of local pain is evidence of viruses. These are two signs by which the nature of pathogens can be distinguished. But even if you think that you have identified the cause of the disease, do not neglect a visit to the therapist. It won't take long, but it may save you from unpleasant consequences

self-medication.

The most common causes of colds A cold is a disease associated with hypothermia.

This is a simple truth that humanity figured out a long time ago. But whether a viral or bacterial infection was the cause of the disease, people were able to distinguish much later. But today not everyone knows what happens to tissues during hypothermia, why they become inflamed and stop functioning normally. While the answers to these questions would help shape the right tactics

As is known, painful changes in human tissues and organs occur only under the influence of pathogenic microorganisms. The throat itself does not become inflamed. Qatar is a tissue reaction to the activity of pathogenic microbes (viral or bacterial origin). Sometimes the pathogens are fungi or protozoan microorganisms, but colds are not affected by such agents.

Most frequent illnesses cold-related:

• influenza and ARVI (viral infections);
• pharyngitis and laryngitis (can be viral or bacterial in nature);
• pneumonia and tonsillitis (bacterial diseases).

What process that promotes damage to the tissues of the upper respiratory tract by pathogens is triggered when the body is hypothermic? Staying in a cold environment causes a decrease in temperature human body. Such a decrease signals that it is necessary to increase blood flow to internal organs, and the blood supply to the upper respiratory tract is noticeably reduced.

Normal human body temperature (36.6°C) is high for viral and bacterial agents. When they find themselves in such conditions, they die. But as the temperature decreases, a favorable environment for pathogenic microbes appears in the tissues of the nasopharynx; they take root and begin to multiply.

At the moment of hypothermia, they weaken significantly protective functions body. If pathogens enter the mucous membrane, they practically do not encounter immune resistance and begin to actively multiply, poisoning this area with the products of their vital activity. For a viral pathogen or bacterium to cause acute inflammation, just a little time (several hours) is enough. Then the preventive measures of the immune system will not cope with the toxins of pathogenic microorganisms.

Except infectious diseases associated with hypothermia, diseases caused by infection from carriers of pathogenic microbes are also common. Such infections include meningitis, measles, whooping cough, etc.

Why do you need to be able to distinguish the cause of a cold?

If we consider the initial symptoms of infections caused by different pathogens, they are similar. Determining what the difference is is very difficult. Typical cold symptoms include:

• aching bones;
• sore throat;
• headache;
• runny nose;
• general weakness and malaise.

Even a doctor cannot always immediately distinguish ARVI from pharyngitis. But already at this stage of the disease it is necessary to start treatment, because developing infection It's becoming more dangerous every hour. The first measures must be taken with extreme caution: products that fight bacteria cannot destroy viral infection, A antiviral drugs are useless in the fight against bacterial infections.

For this reason, recognition of the cause of the disease should not be neglected. Until this reason is clarified, it is only recommended to increase the general immunity of the body, which in itself will have a positive effect on treatment.

How to distinguish a bacterial infection

Microbiology deals with the scientific basis of how to distinguish different infectious agents. But even with the current level of development of science, it has not yet been developed operational methods determining the nature of pathogens in patients. The difference can only be established on the basis laboratory tests blood and urine. The difference is recorded in the content of leukocytes.

A good opportunity to distinguish one from the other would be a test for respiratory infection caused by viruses or bacteria. But the production of such tests is only in the future, and this moment they are not on sale. Therefore, in everyday life we ​​will have to try for a long time to distinguish pathogens, relying only on our own knowledge and an attentive approach to health.

To understand how to distinguish the pathogenic effects of pathogenic bacteria from the destructive effects of viruses, you need to have a minimal understanding of the nature of both.

A bacterium is a single-celled microorganism that can live and function independently. Tissue affected pathogenic bacteria, exposed to bacterial toxins. To access nutrients, the bacterium poisons the cells human body. With a sufficient amount of organic matter and the absence of immune resistance, the bacterial colony grows very quickly in the affected area.

Symptoms of bacterial infection are:

• rapidly growing inflammation in a localized area of ​​tissue (a focus of inflammation can be observed in visible areas of the upper respiratory tract);
• absence of high temperature in the first stages.

If your throat hurts and burns, but there is no fever and your general condition is satisfactory, then most likely the upper Airways infected with streptococcus or staphylococcus. These are bacteria that are symbionts of humans. As long as the immune system is functioning properly, they exist on the surface of tissues in a suppressed state. But if immunity weakens, then favorable conditions arise for these pathogens.

Most often, bacterial infections are treated with antibiotics. But if a person initially strong immunity and after a slight decline it has recovered, then there is a high probability that the disease will recede even without antibiotics.

How to distinguish a viral infection

Viral infection – more common colds. To get sick, only two conditions are enough:

• penetration of the virus into the body;
• lack of developed immunity in humans this species viruses.

The virus itself is not even an organism, but a part of a DNA or RNA molecule that has a mechanism for insertion into living full-fledged cells. That is, a foreign molecule with its own program of action penetrates into tissue cells of the human body containing its own DNA and RNA and begins to multiply in favorable environment. The donor cell dies, releasing a mass of multiplied viruses into the intercellular space that infect healthy cells.

The infection spreads very quickly, and already in the first hours of infection the body responds high temperature, headache and runny nose. There are practically no foci of inflammation on the visible surfaces of the respiratory tract. This is the difference between a virus and the action of a bacterial pathogen.

A generalized viral infection spreads until the body finds an immune response to such an attack. The patient’s task at this moment is to provide maximum support protective forces your immunity, for which it is recommended bed rest, drinking plenty of fluids, taking vitamins and a gentle diet.

Childhood diseases

Colds in children are the same as in adults. The only difference is that an adult can independently analyze internal state, and the parents should help the child. To determine whether a viral or bacterial infection is the cause of a child's illness:

• inspect the upper respiratory tract for inflammation;
• control body temperature;
• watch for mucous discharge.

The information collected over a few hours of observation will help you make preliminary conclusion and distinguish the pathogen by choosing between a viral and bacterial infection.

Cases cannot be excluded when both viral and bacterial infectious agents, the so-called mixed infections. They are possible with a sharp weakening of the immune system. It’s too late to figure out whether it’s a bacteria or a virus. Self-medication in such cases is strictly contraindicated, since it is impossible to mix antibacterial and antiviral therapy. Therefore, if you suspect a complication, contact your doctor immediately.