Bacteremia is characteristic of. Description of the disease bacteremia

Doctors have long established that the inflammatory processes that accompany many serious diseases are a reaction of the body’s immune system to infection, helping to destroy pathogens. But inflammation is also observed in diseases that are traditionally considered unrelated to microbial attacks: heart attacks, strokes, Alzheimer's disease and diabetes.

• Reuters

In parallel with inflammation in the body, blood clotting usually increases, the level of iron in it increases and so-called abnormal proteins appear, resulting from mutagenic errors in synthesis or due to external chemical influences. Scientists do not yet know why such different diseases are associated with such similar symptoms. But a discovery made by Douglas Kell of the University of Manchester and Recia Pretorius of the University of Pretoria, reported by The New Scientist, may shed light on the mystery.

Traditionally, it was believed that the blood of a healthy person is free of bacteria, since when sown in a nutrient medium in a Petri dish (a special vessel used in microbiology), no growth of microorganisms was observed. However, recent studies using DNA sequencing methods have shown that about a thousand bacteria “sleep” in every milliliter of our blood. In a dormant, “dormant” state, they practically do not divide and do not pose a serious threat to the body (although they do not react to medications). But an increase in the level of iron in the blood brings bacteria out of “hibernation”, and they begin their destructive work. Microorganisms begin to synthesize lipopolysaccharides (LPS) - large molecules found on their outer cell membrane. They awaken the immune system and, as a result, cause inflammation.

Unusual Suspect

Kell and Pretorius decided to find out whether there was a connection between LPS and the formation of blood clots. Since most bacteria enter the bloodstream from the intestines, the experiment used the common E. coli (Escherichia coli), which lives in the lower intestines of most warm-blooded animals, including humans. This bacterium has long been used as a model microorganism in laboratory research and has been well studied. Scientists mixed the lipopolysaccharides secreted by E. coli with fibrinogen, a colorless protein found in blood plasma that plays an important role in the blood clotting process. During inflammatory processes and death of body tissue, the level of fibrinogen increases sharply. In the blood of a healthy person, during enzymatic cleavage during the coagulation process, fibrinogen polymerizes and precipitates into an insoluble fibrin precipitate of a filamentous shape. However, when exposed to E. coli LPS, fibrinogen has been shown to form abnormal fibrin clots, similar in shape and size to those seen in heart attacks, strokes, and deep vein thrombosis. Due to the abnormal structure of these clots, they are not broken down by blood enzymes, which leads to blood clots entering the bloodstream and can cause a stroke or heart attack. Moreover, to begin the process of formation of abnormal clots, only one molecule of LPS per several hundred million molecules of fibrinogen is enough.

According to the researchers, this proves that LPS works as a catalyst for the process, changing the structure of fibrinogen, and the reaction is of a chain nature, transmitted from protein to protein, similar to the deformation of prion proteins that cause the notorious Creutzfeldt-Jakob disease (spongiform encephalopathy, in commonly known as “mad cow disease”). And since LPS is a trigger of inflammation, as a result of which the amount of fibrinogen in the blood increases, the process becomes an avalanche.

“There is no big discovery there. As for thousands of bacteria in one milliliter of blood, this is not entirely true. Finnish researchers have long ago established that many viruses and nanobacteria (less than 0.1-0.2 microns) live in our blood. In general, we coexist with bacteria and viruses; life on Earth began with them and will end with them. The fact that lipopolysaccharides are an important element of our immune system is also a well-known fact; they knew this half a century ago. And it has long been known that bacteria play a big role in it. If a child does not fall or hurt his knees in childhood, then he does not develop immunity to many microorganisms. That’s why, by the way, people in villages get sick less often than in cities. So I don’t see any revelation in this work. Unfortunately, I have come across a lot of young researchers who pass off any of their experiments as some kind of discovery. Still, the history of science must be studied and known.”
Valery Fedorovich Galchenko, corresponding member of the Russian Academy of Sciences, head of the scientific direction "Microbiology" of the Federal Research Center of Biotechnology of the Russian Academy of Sciences

Inflammatory processes are usually accompanied by an increased level of free iron in the blood - this is observed, in particular, in diseases such as Alzheimer's disease and rheumatoid arthritis. Scientists believe that bacteria in the blood that have emerged from a dormant state may be associated with these diseases, forming amyloids. This is confirmed by data obtained by researchers at Harvard Medical School, published this spring. Scientists injected bacteria into the brains of mice and found that amyloid deposits formed in the rodents within 24 hours.

Stroke is considered the leading cause of death in the modern world, and the number of people suffering from Alzheimer's disease may rise to 100 million by 2050. Kell and Pretorius's discovery could be an important factor in the search for treatments for these and other diseases related to the circulatory system. Likely ways, according to The New Scientist, could be, for example, removing dormant bacteria from the body or blocking the proteins they produce.

Vladislav Krylov

Bacteria surround us all the time. There are a huge number of them on the surface of the skin; opportunistic bacteria are also present in the intestines. In addition, they can enter the genitourinary, respiratory and other systems of the body. However, the most dangerous condition is the presence of bacteria in the bloodstream, or bacteremia (forumdisplay).

Main reasons

Bacteremia is a pathological process that can be caused by many different reasons, because there are a huge number of ways for bacteria to enter the body. Most often they enter the bloodstream for the following reasons:

• Violation of the rules of asepsis (preventing microorganisms from entering a sterile environment) and antiseptics (eliminating microorganisms where they may be) during surgical interventions.
• Long-term severe illnesses that require long-term injection interventions or artificial ventilation. Prolonged presence of foreign objects in the human body increases the chances of bacteria entering the bloodstream.
• Secondary bacteremia during infections is a condition that is characterized by the colonization of bloodstream bacteria against the background of an existing infection (gastrointestinal tract, respiratory system, genitourinary system).
• Risk factors for the development of this condition are injection drug addicts, as well as people with immunodeficiency (HIV-infected).

Thus, bacteremia is typical for people with weakened immune systems and for those whose skin integrity is constantly compromised.

Pathophysiology

Bacteremia is a condition that may not cause any harm to the body for a certain period of time. However, if this process has been observed for a long time, bacteria can migrate to any internal organ, forming a focus of infection and inflammation there. As a result of this, abscesses (purulent foci limited by a capsule) and phlegmon (diffuse purulent inflammations) are formed. Damage to the brain and heart is most dangerous.

In addition, when the valves and internal (endocardium) are damaged, a disease called infective endocarditis occurs. If not diagnosed and treated promptly, this disease causes destruction of the heart valves and leads to the development of heart failure.

Symptoms

As noted above, bacteremia is a process that can be asymptomatic for a long time, without causing any complaints in the patient. However, over time it makes itself felt.

The most typical symptoms are:

• disturbance of general well-being: severe fatigue, weakness;
• fever accompanied by sweating and chills;
• dizziness and headache;
• increased heart rate and breathing;
• Symptoms such as a drop in blood pressure and impaired consciousness may also indicate the development of septic shock.

Sepsis

Perhaps someone has the opinion that bacteremia and sepsis are two inseparable concepts, but this is not so. The first characterizes only the fact of the presence of bacteria in the body, while sepsis is a more serious condition. And to make such a diagnosis, the following signs must be present:

• body temperature above 38 °C or below 36 °C;
• heartbeat more than 90 beats per minute;
• respiratory rate more than 20 cycles per minute;
• the number of leukocytes in the blood is more than 12 thousand/mm 3 or less than 4 thousand/mm 3;
• presence of bacteria in the bloodstream during blood culture.

Although, according to recent studies, the presence of bacteria in the blood is no longer a mandatory criterion for sepsis. That is, simply put, sepsis is an excessive reaction of the body to an infection.

Septic shock and multiple organ failure

Septic shock is considered the next stage of sepsis, which is accompanied by a drop in systolic blood pressure below 90 mm Hg. Art. Moreover, this hypotension is unable to be corrected by infusion of saline solutions. This means that the function of the cardiovascular system is so impaired that even increasing the volume of circulating blood using saline solutions cannot increase blood pressure.

Multiple organ failure is a term that refers to dysfunction of almost all organs and systems of the body. It manifests itself as a decrease in the amount of urine excreted (oliguria), an even greater drop in blood pressure, respiratory depression, etc.

Thus, the concepts of bacteremia, septicemia and toxinemia are closely interrelated. The presence of bacteria and their breakdown in the blood causes the accumulation of toxins (toxemia), and these two conditions, in turn, lead to the development of septicemia.

Diagnostics

When a patient presents any of the complaints listed above, the doctor first issues a referral for a general blood test. If this analysis confirms the presence of a bacterial infection in the body (increased number of white blood cells - leukocytosis, mainly due to an increase in neutrophils - neutrophilosis), the next step will be a bacteriological examination using blood culture to determine bacteremia.

In addition, if the presence of bacteria was detected during culture, it is necessary to perform an x-ray of the chest organs, an ultrasound examination of the chest and abdominal cavities, and pelvic organs. These examination methods are necessary for the timely detection of purulent foci in the internal organs.

Treatment

Even before blood culture results are obtained, a patient with suspected bacteremia is prescribed broad-spectrum antibiotics. This type of therapy is called empirical therapy. Based on the results of the culture (this may take several days), it is possible to change the antibiotic, depending on which drug the type of bacteria cultured is sensitive to.

As a rule, with the right antibiotic, your health improves on the second day of therapy. However, there is no need to interrupt antibiotic therapy before the time prescribed by the attending physician.

In addition to antibiotics, symptomatic therapy is also necessary to alleviate the patient’s condition:

• antipyretics at high temperatures (“Paracetamol”, “Ibuprofen”);
• infusion of saline solutions for low blood pressure (isotonic sodium chloride solution, Disol, Acesol).

If there are purulent foci in the internal organs, surgical intervention is possible.

Bacteremia is a truly dangerous condition. When it is detected, it is necessary not only to eliminate the presence of bacteria in the bloodstream, but also to find out the root cause of their appearance and fight it.

It is well known that a clinical blood test of a person can provide detailed information about the state of the body. Standard general analysis gives a small number of indicators: five to six. These include data on whether the body is affected by a bacterial infection (this is indicated by the level of leukocytes). But this is not information that can indicate the presence of bacteria in the blood. Bacterial contamination is revealed by more detailed examination.

Human blood should not contain strains of bacteria or viruses. Any presence of microorganisms is a pathology and requires identification of the cause of bacterial contamination and subsequent treatment.

But deviations from the norm are not uncommon. Bacteremia is bacterial contamination of human blood plasma. The presence of bacteria is determined by conducting a bacteriological blood test.

To conduct a bacteriological study, blood is taken from a vein for analysis with a sterile syringe. Next, bacterial cultures are performed in the laboratory to identify the microflora and, if necessary, determine antibacterial therapy.

The main types of bacteria that can be found in blood plasma (it is plasma that is studied):

• staphylococci;
• coli;
• streptococcus;
• Klebsiella

If these microorganisms are present in the plasma, this indicates that the cause of their appearance is microbial damage to some internal organ. Bacteria entered the plasma only as a result of the spread of infection from the affected areas of certain tissues. There can be no other way for them to spread.

Treatment of microbial infection of the body is carried out using antibiotics. Treatment can be stopped after the symptoms disappear and based on the results of a study of blood plasma, which should not contain strains of microorganisms.

Helicobacter

One of the most common bacterial contaminations of the human body is the detection of the Helicobacter pylori bacterium in the stomach and gastrointestinal tract. Its presence can be detected in both children and adults.

However, if the test for Helicobacter is positive, this does not mean that there is a possibility of developing symptoms, the relief of which will require a long course of treatment.

A few facts about the presence of Helicobacter pylori in humans:

1. In most cases, these microorganisms can cause stomach or duodenal ulcers.
2. Even completely healthy people can be carriers of Helicobacter.
3. Microorganisms themselves cannot be detected in blood plasma. Their presence is established by the presence of antibodies that the body produces when a foreign protein is detected (the protein that Helicobacter synthesizes).
4. When conducting research, a standard for the presence of antibodies was established, by which it can be determined: whether there is a danger from the presence of these microorganisms, or whether their vital activity will not cause harm to the gastrointestinal tract (1:5 is the norm, more than 1:20 is time to sound the alarm).

Due to the fact that the Helicobacter test shows a reaction to the presence of a pathogenic microbe, an immune response (exceeding the norm of antibodies) may be present for some time after antibacterial therapy.

When conducting research, not only bacteria, but also viruses can be detected. The presence of viruses is determined by the remnants of individual genetic material - RNA (organic molecules responsible for protein synthesis) or DNA.

RNA determines whether a child or adult is infected with the rubella virus. This analysis is carried out in the presence of specific symptoms (rash and swollen lymph nodes).

Based on DNA residues, if symptoms exist in both a child and an adult, the presence of the herpes virus (Epstein-Barr) in the body is determined. Also, by RNA, in the presence of symptoms, the genetic material of the hepatitis C virus is detected in the blood.

A certain amount of hepatitis C viruses can also be present in the human body without causing much harm. The quantitative indicators of this norm should be consulted in the laboratory that carried out the blood study, since this norm is different for a child and for an adult. In addition, the indicators depend on the research design.

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Presence of bacteria in the blood.

Reasons

Penetration of the pathogen into the blood is observed in many infectious diseases and is an integral or probable component of their development.

Mild, short-term bacteremia can also occur even when a person clenches his jaw, since bacteria living on the gums within the teeth enter the bloodstream. Bacteria often enter the bloodstream from the intestines, but they are quickly destroyed as the blood passes through the liver.

The number of microorganisms per unit volume of blood depends on the virulence of the pathogen and the resistance of the patient’s body. With prolonged and severe bacteremia, generalized and, in particular, septic forms of the infectious process traditionally form.

Symptoms

Because the body can deal with a small number of bacteria quickly, symptoms of temporary bacteremia appear in rare cases. However, as soon as sepsis develops, chills occur, body temperature rises, weakness, nausea, vomiting and diarrhea are detected.

If treatment is not started, the infectious agents spread throughout the body and so-called metastatic foci of infection are formed.

The consequence of this may be meningitis - inflammation of the lining of the brain, pericarditis - inflammation of the outer lining of the heart, endocarditis - inflammation of the inner lining of the heart, osteomyelitis - inflammation of bone tissue. With sepsis, abscesses (collections of pus) can form throughout the body.

Diagnostics

A person who has a focus of infection in any organ suddenly experiences a sharp rise in body temperature. If sepsis develops, the number of white blood cells traditionally increases significantly. To identify the “culprit” microorganism, blood cultures are performed. However, it is difficult to isolate bacteria in a blood culture, especially if the person is taking antibiotics. For culture, sputum material from the lungs, urine, discharge from wounds and from places where catheters are inserted are also taken.

Treatment

Bacteremia associated with surgery or catheter insertion into the urinary tract traditionally requires no treatment, especially if the catheter is promptly removed. However, before such procedures are performed, people at increased risk of developing inflammation in response to bacteremia, such as patients with heart valve disease or a weakened immune system, are given prophylactic antibiotics.