Blood for typhoid. Tests for typhoid fever: types and results. When to take an analysis

Typhoid fever- an acute infectious disease that affects the intestines and its lymph nodes. The disease is accompanied by an increase in the liver and spleen, severe intoxication with high fever and clouding of consciousness.

Although the frequency of the disease has decreased over the past hundred years, the problem still remains very relevant. About 20 million people are infected with typhoid every year in the world, and 800 thousand die from this disease. More often people get sick in developing countries, where there is not enough drinking water, low sanitary culture and street food trade flourishes. Therefore, tourists who go to Central Asia, Africa or South America should be extremely careful.

It is especially dangerous to swim in ponds that can be contaminated with sewage and buy ready-made meals in the markets. The highest risk is associated with dairy and meat products, in which the bacterium at a temperature of +18 C begins to actively multiply.

In Russia, thanks to sanitary control, it was possible to almost completely defeat typhoid fever. But in recent years, a new danger has emerged. Migrants who come to work and our tourists bring typhoid salmonella from other countries. One sick person can infect many people, especially if he works in the food industry.

You can get typhoid fever from a sick person and from a carrier who feels completely healthy. The route of transmission is fecal-oral. This means that the bacterium is excreted from the intestines of a sick person and enters the mouth of a healthy person through food, drinking water, dirty hands or household items.

Large outbreaks and epidemics occur in the summer-autumn period. At high temperatures, the typhoid fever bacillus multiplies rapidly. In addition, flies contribute to its spread.

Susceptibility to the bacterium that causes typhoid fever is high and people of any age can become infected. But according to statistics, children and young people under 30 are more likely to get sick. This is due to the fact that they are more active: they travel more often and eat away from home.

The causative agent of typhoid fever

Typhoid fever is distinguished from other diseases by the following symptoms:

• heat
• skin is pale and dry
• enlarged dry tongue, coated in the center and clean around the edges
• soreness and rumbling under the right rib
• slight rash in the form of red spots in the upper abdomen and lower chest (appear on days 8-9)
• decrease in heart rate at high temperatures
• signs of intoxication: weakness, lethargy, depression, lethargy, headache

General clinical tests

1. Hemogram or clinical (general) blood test. Determines the amount of all the elements that make up the blood. With typhoid fever, the following changes appear:
   • moderate leukocytosis - in the first days of the disease, the number of leukocytes slightly increases and the ratio of their types changes. but during the week their number sharply decreases.
   • leukopenia - low white blood cell count
   • aneosinophilia - the absence of eosinophils in the blood
   • relative lymphocytosis - an increase in the percentage of lymphocytes compared to all other leukocytes.
   • increased ESR - the erythrocyte sedimentation rate increases, but not significantly
2. General urine analysis. Urinalysis in the laboratory. The laboratory assistant studies the physicochemical characteristics and examines the sediment under a microscope. With typhoid fever in the urine are found:
   • erythrocytes
   • cylinders

For laboratory diagnosis, blood, urine, bile and feces are taken. They are inoculated on nutrient media and placed in a thermostat, where the temperature is constantly maintained at 37 C. If there are typhoid bacteria in the tests, they form colonies that can be examined under a microscope. Bacteria in the blood can only be found in sick people, and in feces and urine, salmonella can be found in both a sick person and a bacteriocarrier.

1. Hemoculture- isolation of salmonella typhoid fever from the blood. This is the earliest and most accurate diagnostic method. Bacteria appear in the blood during the incubation period and remain until the end of the disease. To detect them, blood (10 ml) is taken from the cubital vein and inoculated on Rappoport's liquid nutrient medium. A preliminary result can be obtained on the second day, but the entire study lasts 4 days.


2. coproculture- isolation of typhoid bacteria from feces. Salmonella in the contents of the intestine is found from 8-10 days of illness. In this case, dense nutrient media are used.


3. Urinoculture– detection of typhoid bacteria in urine. It is examined not earlier than on the 7th-10th day of illness.


4. bile culture- for the study of bile, a probe is inserted into the small intestine. Bile is collected in sterile test tubes and inoculated. This study is carried out after recovery.


5. Bone marrow culture- the sample is taken during the puncture in the second third week of illness. It is carried out if there is a suspicion that typhoid fever has severely damaged the bone marrow.

Serological testing methods

Starting from the second week, special antigens appear in the blood. These are particles of the shell and flagella of Salmonella typhoid. They can be detected using studies based on immune responses. For analysis, blood is taken from a finger and serum is separated from it.

1. Vidal reaction- determines whether there are O- and H- antigens in the serum of venous blood. After interacting with special substances, cells containing particles of typhoid bacteria stick together and precipitate. A positive result can be not only in a patient, but also in a person who has been ill, a carrier, or after vaccination. To know for sure that bacteria multiply in the blood, the reaction is carried out several times. In case of illness, the titer (level) of antibodies is 1:200 and is constantly increasing.
2. Passive hemagglutination reaction (RPHA with cysteine)- the blood serum of a sick person glues (aggluten) erythrocytes coated with antigens. This study also needs to be done several times to see if the antibody titer increases. In a sick person, it is 1:40 and can increase 3 times. The first analysis is taken on day 5, and then as needed with an interval of 5 days. Vi and H antibodies may be elevated in convalescents and carriers.

Treatment for typhoid fever

Treatment of typhoid fever goes in several directions at once.

Infection control

In severe forms, a combination of antibiotics Ampicillin and Gentamicin is used. Or new generation drugs Azithromycin, Ciprofloxacin.

If antibiotics do not work or are poorly tolerated, then antimicrobials of other groups are prescribed: Biseptol, Bactrim, Septrim, Cotrimoxazole. They are taken 2 tablets 2 times a day. The course is 3-4 weeks.

Fight against intoxication and dehydration

In a moderate condition, it is necessary to cleanse not only the intestines, but also the blood. To do this, glucose-salt solutions are administered intravenously so that toxins are quickly excreted by the kidneys. Use drugs: Lactasol, Quartasol, Acesol, 5% glucose solution. They are prescribed up to 1.5 liters per day.

If, despite all efforts, intoxication increases, then Prednisolone is prescribed in tablets for 5 days.
Oxygen therapy helps to fight intoxication well. Oxygen is administered through catheters into the nose or a special oxygen pressure chamber is used.

If the medicines do not help, and the condition continues to worsen for three days, then a blood transfusion is done.

Improvement in general condition

Angioprotector Askorutin helps to improve the functioning of small capillaries, normalize metabolism and blood circulation.

Tincture of ginseng, magnolia vine or eleutherococcus improves the general condition, gives strength and improves the tone of the nervous system. Natural herbal preparations are used together with a complex of vitamins: A, B, C, E.

Diet for typhoid fever

After discharge from the hospital (6-7 weeks of illness), the menu can be gradually expanded. Do not immediately lean on the forbidden smoked and fatty foods. Try small portions of new foods for 7-10 days.

Folk remedies for typhoid fever

For the treatment of typhoid fever during epidemics, decoctions of blackcurrant or rose hips, as well as coffee with lemon, were often used.

Herbal infusions help speed up the healing of ulcers in the intestines and cleanse the blood of toxins. Pour 1 tablespoon of burnet roots with a glass of hot water and boil for half an hour. Take every 2-3 hours for a tablespoon.

Pour 1 tablespoon of St. John's wort with a glass of boiling water and insist in a thermos for 1 hour. Drink in small sips throughout the day.

Prepare a mixture of centaury herbs, sage and chamomile. Pour 1 tablespoon of the collection with a glass of boiling water, leave for 30 minutes and strain. Drink 7-8 times a day for a teaspoon.

Folk remedies can be an addition to the treatment prescribed by the infectious disease doctor. But remember, do not try to defeat the disease on your own. During the treatment of typhoid fever, antibiotics are indispensable.

Dispensary observation

They can be discharged from the hospital no earlier than a month after the onset of the disease or 21 days after the temperature drops below 37 C. Before discharge, feces and urine are analyzed 3 times. In the event that salmonella typhoid fever is not found in the discharge, they are allowed to go home.

Typhoid fever has the insidious feature of "returning." This recurrence of the disease is called relapse. In order not to miss the new development of bacteria in the body and carriage, after discharge, the patient will often have to communicate with doctors and take tests.

The first two months, the inspection is carried out once a week. 10 days after discharge, you will need to pass feces and urine 5 times with an interval of 1-2 days. In the future, visits to the clinic will be much less frequent. After 4 months, it is necessary to pass an analysis of bile and blood for the reaction of RPHA with cysteine. If the result is negative and no traces of bacteria are detected, then the person will be removed from the register.

Prevention of typhoid fever

Vaccination or vaccine against typhoid fever

Who needs to be vaccinated?

Since children become infected more often, they need the vaccine more. Therefore, in areas where cases of the disease often occur (25 patients per 100,000 population), children 5-19 years old are vaccinated. Vaccination is also recommended for people at risk. For example, family members where there is a sick person and medical workers who encounter this infection.
In our country, general mandatory vaccination is carried out only during epidemics. In other cases, doctors recommend, but do not force, to be vaccinated against typhoid fever.

In recent years, tourists who are going to visit Asia, South America and Africa have also been vaccinated against typhoid fever. In countries dangerous in relation to typhoid fever without a certificate of vaccination may not be allowed. You can clarify this issue with tour operators. Vaccination must be done no later than 1-2 weeks before departure, so that immunity can form. It helps protect travelers and their families, as well as prevent the spread of this disease in Russia.

How effective are typhoid vaccines?

The efficiency of different manufacturers is slightly different, but approximately the same. It is 60-75%. This does not mean that the vaccine does not work at all on the remaining 25-40% of people. If they get sick, then in a milder form.
Remember that the vaccine does not guarantee against infection. Therefore, even if you were vaccinated before the trip, you still have to take precautions.

What vaccines are used?

Hygiene

But each of us must take care of our own health. Especially in countries where typhoid fever is common. Follow basic safety rules:

• drink only bottled water
• do not buy groceries on the streets
• if there is no other way, buy dishes that have been boiled / fried, and not salads or desserts with cream
• wash your hands after using the toilet and before eating
• do not swim in open water, where drains from sewers can get into

Typhoid fever is a serious illness caused by an infection. If left untreated, it can lead to the death of the patient. The causative agent is a bacterium belonging to the varieties of Salmonella. Also known as "E. coli". This is a fairly tenacious microorganism that poses a threat to humans. If characteristic symptoms occur, the specialist prescribes an analysis to determine the presence of the pathogen. Blood for typhoid fever is a simple procedure that helps to establish the risk of developing the disease.

Microorganisms that cause disease enter the body through the household route. Often the infection disappears with the use of water. In the absence of therapy, the disease is life-threatening, as it provokes the development of serious complications. Among them, bleeding in the intestine and perforation of the intestine are distinguished.

Among the studies conducted to diagnose typhoid fever, a blood test is considered more informative. As additional procedures, a hematological examination is prescribed to determine the rate of obtaining an erythrocyte sediment, as well as the number of leukocytes. The ratio of their elements is established.

The material sampling procedure and its research are carried out for individual organizations and their workers. Data on the results are entered in the sanitary book. For a sanitary book, employees are required to take an analysis:

1. Catering and food industry enterprises.
2. School and preschool institutions.
3. Public service organizations. These are employees of swimming pools, hotels, hairdressers, hydropathic clinics, baths.

This also applies to medical staff, pharmacists and drivers who transport food.

Preparation and delivery

In order for the results of the blood test to be correct, you should stop taking medication three days before the material sampling procedure. For two days you can not drink alcohol. On the day of the sampling procedure for the establishment of typhoid pathogens, you must refuse to use milk and other products that contain it, smoked, spicy seasonings, fried. Smoking is prohibited one hour before the blood sampling procedure.

Together with a blood test for typhoid fever, the following studies are also prescribed:

1. General analysis. It is prescribed for suspected development of infectious pathologies. But typhoid fever can be detected indirectly. Leukopenia, eosinophil deficiency and an increase in ESR are also detected.
2. Bakposev. The duration of the analysis is about five days. Material for research is taken from the mucous membrane of the urethra or vagina using a special swab. After that, it is placed in a special environment and sent to the laboratory.
3. Biochemical analysis. Helps to fix the presence of proteins that indicate an acute course of pathology.
4. Serological examination of blood for typhus. The diagnostic method helps to detect antibodies already on the fourth day from the onset of infection.
5. Immunoenzymatic analysis to determine the presence of antibodies to typhoid.

The duration of the blood sampling procedure is no more than 5-7 minutes. Many patients are interested in where the blood comes from. The material is taken from a vein. To do this, the specialist treats the puncture site with a cotton swab dipped in an alcohol solution.

Then a tourniquet is applied above the elbow and a needle is inserted into the vein. Blood is taken, and the puncture site is then again treated with a cotton swab dipped in alcohol. The patient should bend the arm at the elbow and wait 10 minutes.

How much analysis is done

The duration of a laboratory test to determine the presence of antibodies to typhoid fever is from 3 to 10 days. It depends on the method of studying biological material and the workload of the laboratory.

The attending physician will tell you how much the analysis is done and when to get it. Most often, the results of the study are ready in 4-5 days.

Decryption

A positive result is established in the presence of antibodies to microorganisms that provoke the development of the disease. These indicators indicate either the presence of a pathology that occurs in the acute stage, or an already transferred disease.

In cases where the final result of a blood test for typhoid fever is negative, this indicates that the disease has just begun to develop or that it was transferred some time ago. A negative result also indicates that the person is completely healthy and has not been infected with typhoid fever.

In some cases, a false positive result is noted. This is caused by other infections such as Salmonella, hemolysis of a plasma sample, or prolonged use of antibacterial drugs.

Prevention

The most effective prevention is the typhoid vaccine. Vaccination is given to children at the age of two years. Secondary vaccination - after three years. Vaccinations for adults are given in the event of a threatening situation, when there is a high probability of developing a pathology, or when leaving for an area where a high level of the disease has been established.

Immunity after vaccination, depending on the type of vaccine, lasts for 10 years. During travel or work in adverse conditions, city districts, as well as their residents, are recommended to carry out revaccination in 1-3 years.

Non-specific measures to prevent the occurrence of typhoid fever include:

1. Hand hygiene. Hands should be washed after returning from the street, communicating with animals, before eating.
2. The use of boiled water. Do not drink water from unreliable sources.
3. Sterilization of dairy products. Milk should be boiled before drinking.
4. Conduct heat treatment of meat products.
5. Control the freshness of food.

For the purpose of preventive measures, timely detection of infection in people whose professional duties are related to the manufacture or preparation of food is carried out. It is very important to monitor the health of children attending preschool institutions. Water supply and wastewater disinfection are also monitored.

It belongs to the group of typhoid and paratyphoid diseases, which have a high contagiousness, fecal-oral transmission of the pathogen and a similar clinical picture. This pathology is characterized by a severe course, the presence of fever, intoxication and damage to the lymphatic apparatus of the intestine.

Timely diagnosis and treatment of typhoid fever determines the prognosis for recovery, and also reduces the possibility of spreading the infection.

Establishing diagnosis

From the point of view of the effectiveness of the therapy and anti-epidemic measures, the diagnosis of typhoid fever should be established within the first 5-10 days. After all, it is during this period that antibiotic therapy is most effective, and the patient is minimally contagious.

A doctor can suspect typhoid fever based on clinical and epidemiological data. A combination of the following symptoms should alert him:

• increase in fever and intoxication without distinct organ lesions;
• relative (discrepancy between the pulse rate and high body temperature);
• pale skin;
• roseolous rash;
• characteristic changes in the tongue (its swelling, grayish-yellow plaque, teeth marks);
• hepatolienal syndrome (and);
• sleep disturbance;
• adynamia.

From epidemiological data, of particular importance is:

• having contact with a febrile patient;
• stay in a territory unfavorable for typhoid fever;
• drinking water from open reservoirs;
• eating unwashed vegetables and fruits;
• use for food purposes purchased from individuals.

All persons with a temperature of 5 days or more should be examined for typhoid infection.

Testing for typhoid fever

The diagnosis of typhoid fever must have laboratory confirmation. For this purpose, the following research methods are used:

1. Isolation of the pathogen's blood culture (blood sampling is carried out at the height of fever for 2-3 days daily; inoculation is performed on nutrient media containing bile).
2. Immunofluorescence method (allows you to get a preliminary result 10-12 hours after sowing).
3. Bacteriological examination of feces, urine and duodenal contents (may be reliable from the 2nd week of illness; the results are evaluated after 4-5 days).
4. Determination of antibody titer and its increase by studying paired blood sera in the reaction of indirect agglutination and complement fixation (a titer of 1:200 is considered diagnostic; it becomes positive from 5-7 days of illness).
5. Enzyme immunoassay (a highly sensitive method based on the detection of complexes of microbial antigen and protective antibodies in the test material).

It should be noted that in addition to specific diagnostic methods, changes are informative:

• a decrease in the total number of leukocytes and neutrophils with a shift in the white blood formula to the left;
• relative lymphocytosis;
• increase in ESR;
• decrease in hemoglobin and platelet levels;
• absence of eosinophils.

Differential Diagnosis

Considering that at the beginning of the disease, the diagnosis of typhoid fever is difficult due to the scarcity of clinical manifestations, it must be distinguished from many pathological conditions that occur with fever and intoxication:

• and other SARS;
• sepsis, etc.

Principles of treatment

All patients with an established diagnosis of typhoid fever or suspicion of it are subject to mandatory hospitalization with isolation and anti-epidemic measures in the focus of infection. Contact persons are monitored for a possible incubation period (21 days).

Treatment is carried out taking into account:

• the severity of the disease;
• phases of the pathological process;
• the presence of complications and comorbidities.

Such patients are provided with:

• peace;
• bed rest in the acute period;
• sparing diet.

Food should not burden the digestive system and at the same time should be high in calories. Pureed dishes and plentiful drinking (water, tea, fruit drinks) are recommended.

The basis of treatment is antibacterial drugs, taking into account the sensitivity of the pathogen. For this, medicines from the group can be used:

• chloramphenicols;
• cephalosporins;
• fluoroquinolones;
• macrolides.

The course of treatment continues until the 10th day of normal temperature.

To restore impaired body functions and alleviate the patient's condition, therapeutic measures include:

• detoxification and correction of water and electrolyte balance (infusion of glucose-salt and colloidal solutions);
• fight against hypoxia (oxygen therapy);
• appointment of immunomodulators;
• the use of cardiotropic, hypnotic drugs according to indications;
• vitamin therapy.

The tactics of managing patients with the development of complications has certain features.

• With intestinal bleeding, conservative therapy is carried out with the appointment of cold on the stomach, hunger for 10-12 hours and hemostatic drugs. If the patient has significant blood loss, then he is shown the introduction of plasma-substituting solutions or erythrocyte mass.
• With the development of intestinal perforation, an urgent surgical intervention is performed.

After clinical recovery and normalization of laboratory parameters, but not earlier than 21 days after normalization of body temperature, such persons can be discharged home. They are subject to dispensary observation during the year with periodic laboratory examination. Relapses are treated according to the same principles as the primary disease.

Chronic carriers also need treatment. It includes long-term use of antibiotics and vaccine therapy. After the cessation of bacterial excretion, such persons remain registered, since after a while it can be resumed.

Prevention

To prevent the spread of infection and infection of healthy individuals, the following measures are taken:

• control over the operation of the water supply system and disinfection of drinking water;
• Cleaning of drains;
• compliance with the rules of preparation, storage and sale of food products;
• periodic examination of workers in the food industry and children's institutions;
• timely detection and isolation of patients with typhoid fever, as well as bacteria carriers;
• anti-epidemic measures in the focus of infection;
• dispensary observation of recovered and treated carriers of the infection;
• preventive vaccination in risk groups for the development of the disease (living in an area with a high incidence rate, having constant contact with patients or working in a laboratory with infected material).

At present, thanks to modern methods of diagnosis and treatment, the prognosis for typhoid fever has improved. If earlier mortality reached 20%, then against the background of the use of antibiotics, it decreased to 0.1-0.3%. However, this does not exclude severe cases of the disease with the development of complications, which are much less common, but still possible.

Diagnosis of typhoid fever is difficult due to the difficult differentiation of the disease from similar symptoms of intestinal disorders, tuberculosis or cholera. Tests for the presence of typhoid fever and other studies are usually prescribed at the stage of fixing a constant febrile (38-39 0 C) temperature and stable characteristic signs. In addition to determining the diagnosis of illness, an analysis of typhoid fever is mandatory for catering workers, employees of children's and medical institutions, representatives of the hotel or sanatorium services.

Causes and symptoms of typhoid fever

The causative agent of the infectious disease, the Salmonella typhi bacterium, enters the human body through common objects - for example, toys in kindergarten or personal hygiene items, poorly processed dairy products, dirty water. At whatever age the infection occurs, once ill, a person acquires a stable immunity to re-infection.

According to statistics, the threat of Salmonella bacteria penetration is highest in younger schoolchildren, but this does not exclude the fact that older people are carrying the causative agent of typhoid or the disease in an acute form.

An analysis for typhoid fever is given in the presence of all the characteristic signs of the following (with the exception of a rash, which does not occur in all cases of infection):

• constant thirst with a constant feeling of tightness, dry mouth, blanching and peeling of the skin of the face and body, swelling and covering with a whitish coating of the tongue;
• acute recurrent abdominal pain;
• symptoms of intoxication - vomiting, nausea, poor appetite, loss of strength, sweating;
• difficulty in defecation or diarrhea;
• the occurrence of a rash such as roseola, which become faint when pressed.

Symptoms are characterized by a gradual increase, but in a third of all cases, an acute onset of the disease is possible, with the presence of several symptoms at the same time and, necessarily, a temperature in the range of 38-39 0 C. If the course of the disease is standard, then it will follow this algorithm:

• sudden weakness, poor sleep, problems with stools;
• headaches, increased general malaise, fever;
• the temperature within 3-5 days reaches indicative values ​​up to 39 0 and stops at this mark;
• there are severe pains in the abdomen, gas formation, a person’s reaction to external stimuli is dulled, his condition can be called “inhibited”. In the same period, the appearance of roseola is possible.

Since the onset of symptoms of infection occurs no earlier than the seventh day from the entry of typhoid bacillus into the intestines, it is almost impossible to determine the origin of the infectious agent.

Types of tests for typhoid fever

Even before receiving the results of laboratory tests, the clinical picture of the totality of symptoms allows the doctor to diagnose typhoid fever and begin treatment of the patient in isolation from patients of other groups of diseases. Despite the fact that the diagnosis is based on a comprehensive study of blood, if typhoid is suspected, other samples will be needed - for example, urine, bile, feces.

• you can not take medicines for three days before the delivery of the material;
• no alcoholic beverages should be consumed 24 hours prior to sampling;
• 2-4 hours before the tests, you can not smoke, physically overstrain and refrain from experiences and negative emotions;
• all samples are taken in the morning, on an empty stomach of the patient;
• on the eve of the delivery of biological material, you can not eat: eggs, dairy and sour-milk products, smoked meats, pork, lamb, spicy and salty dishes.

All types of additional examinations that may cause discomfort or require separate preparation should be done after taking laboratory tests.

General blood analysis

A clinical blood test helps to determine the change in the main indicators of the state of the body as a whole. The leading values ​​that indicate the activity of the causative agent of typhoid in the body are the distortion (compared with the norm) of the following data:

• decrease in the level of leukocytes;
• absence of eosinophils in the blood;
• lymphocytosis of relative parameters, which indicates a low immune response;
• high erythrocyte sedimentation rate (ESR indicators);
• critically high values ​​of neutrophils;
• low criteria for the presence of platelets.

Blood sampling for research is carried out from the patient's vein immediately upon admission to the infectious diseases department of the hospital. Subsequently, blood will be taken several more times during the treatment process and before discharge.

Blood chemistry

A biochemical blood test is also taken from a vein before starting antibacterial treatment. The results of the study obtained within 24 hours determine the presence of acute phase proteins synthesized in the liver as a response to an infectious lesion.

Serological blood test

For serological studies, plasma is isolated from the blood of a sick person, where the presence of characteristic antibodies is of decisive importance.

An analysis taken no earlier than the fifth day from the moment the typhoid bacillus enters the intestine is considered effective, since it is this period that the body needs to produce antibodies to the infectious agent.

Overestimated values ​​of detected antibodies indicate a high level of immune response to infection, which is specific in two cases:

• in the process of recovery;
• if a sick person is a carrier of typhoid bacillus.

To obtain a reliable answer, serological studies are carried out on the 7-10th day from the onset of initial symptoms.

Bacterial culture

Bacterial seeding of biological material allows you to detect the disease at an early stage of infection. Blood is most often used as the examined fluid - this is called seeding for blood culture. Blood sampling is preferably done at the moment when the patient's body temperature is above 38 0 C. Rappoport's nutrient medium is used for seeding, into which 15-20 ml of the patient's blood is placed. Then, for ten days, laboratory staff daily observe the growth of bacterial colonies in the sample and, in case of detecting a dynamic development of such, make the next inoculation in a Petri dish. Here, bacteria are analyzed for 24 hours under constant testing, including sensitivity to antibacterial drugs.

Urine culture is indicative at any stage of the disease, but the best period for the detection of the pathogen is from the 21st day from the moment of infection. The principle of conducting test studies of uroculture is the same as when monitoring the patient's blood.

The study of feces is carried out between the third and fifth week of the disease, while only the liquid substance of the feces is considered suitable for sowing. For infectious patients, this type of analysis is rarely used, but it is considered reasonable for periodic examinations of workers with health records.

Immune fluorescence reaction (RIF) and enzyme immunoassay (ELISA)

RIF is an emergency research method performed for suspected typhoid fever, when symptoms are mild or there is reason to believe that a person could become infected. A biological sample taken from a patient is injected with special antibodies stained with fluorescent elements, which, when combined with the antigens of an infectious agent, begin to produce a glow. This characteristic feature, clearly visible when examining the sample under a microscope, allows us to conclude that there is a typhoid bacillus.

ELISA, unlike the previous method for determining antigens and antibodies, can even accurately estimate their number. Based on the data obtained, the doctor concludes that the treatment regimen is correct.

The reaction of indirect hemagglutination (RIHA)

RNGA is one of the most accurate types of diagnostics for suspected typhoid fever, since this reaction is sensitive to 3 antigens of typhoid bacillus. When carrying out this type of analysis, erythrocytes that have a strong immunity to pathogen antigens are evaluated. RNHA is diagnosed several times, and an increase in O-antibody titers is considered normal for a positive response. If increased titers of H- and Vi-antibodies are detected, this indicates an imminent recovery of the patient or his status as a carrier of a bacterial pathogen.

Prevention of typhoid fever

Prevention of typhoid fever adheres to the most strict control in relation to employees of preschool and health institutions, employees of food points and health care institutions. If a carrier of infection is found among the employees of these institutions, two disinfection measures are carried out at the place of work of a sick person.

Individual prevention of an infectious disease is personal hygiene, which includes the mandatory isolation of personal items from public places. To prevent infection through food, you can not eat unwashed fruits and vegetables, unheated dairy products, raw eggs. A great danger is the unboiled tap water or collected from dubious sources, water.

Since children of younger or school age are more susceptible to typhoid infection than the adult population, parents should be more careful to ensure that the employees of the institution visited by their child have all the necessary medical reports on the state of health. This will almost 100% eliminate the possibility of infecting a child with a dangerous typhoid bacillus.

How are tests for typhoid fever performed? What are they? Typhoid fever is classified as an acute intestinal infection, but it stands apart. Usually, with intestinal infections, students begin to study the course of infectious diseases, and the first of them usually comes with typhoid fever and paratyphoid fever A and B, the causative agents of which form a typhoid and paratyphoid group.

Why does this complex course begin with typhoid fever? Yes, because this disease develops in well-defined stages, proceeds predictably, tests for typhoid fever and diagnostic principles are standard and simple, and using the example of typhoid fever, you can fully get acquainted with the typical course of acute intestinal infection.

About typhoid fever

Where does typhoid fever come from? It is a disease of "dirty hands" and contaminated water. The causative agent of typhoid fever is the large microorganism Salmonella from the genus Enterobacteria, and the causative agent of typhus is extremely small rickettsiae.

Usually, when people talk about typhus, the harsh years of the civil war come to mind. But then there were epidemics mainly of typhus. And today every year more than 20 million people, or the population of two cities like Moscow, become infected with typhus. Nearly 900,000 of them die every year. Such outbreaks occur in hot African countries, India, Colombia and Malaysia, Indonesia and Afghanistan. Therefore, a great danger lies in wait for those travelers who underestimate the likelihood of infection.

It is very easy to catch typhoid fever, and the severity of this disease lies primarily in the fact that it begins as a mild ailment with ordinary food poisoning. Such features of this infection led to the fact that all the so-called decreed persons working in the food industry, in educational institutions and medical organizations, must be tested annually for typhoid fever and checked for carriage of typhoid bacilli. The same examination must be carried out by persons working in the food trade.

Features of the course of infection

Typhoid fever occurs with a gradually increasing high temperature, the appearance of abdominal pain, general symptoms of intoxication, characteristic of all infections. A feature of typhoid fever is the reproduction of pathogens that have penetrated through the intestinal wall into the organs of the immune defense of the intestine - into the lymphatic follicles, into the liver, into the cells of the immune defense. In these follicles, pathogens multiply, and then they penetrate the bloodstream through the thoracic lymphatic duct, and this coincides with the onset of the acute period of the disease. The danger characteristic of typhoid fever is intestinal bleeding, intestinal perforation, or necrosis of lymphatic follicles.

At the same time, typhoid fever is a unique disease that requires an abdominal operating room in an infectious diseases hospital. The fact is that a patient diagnosed with typhoid fever and with intestinal bleeding should never be hospitalized in a general surgical department, since he is very contagious. Therefore, a special operating room is equipped in the infectious diseases hospital for such a case, and, if necessary, surgeons are called in to perform an emergency operation.

Typhoid is transmitted only by humans, it is impossible to catch typhoid from animals. You can get sick, I communicate not only with the sick, but also with a healthy carrier. One of the most famous figures in history is the so-called Typhoid Mary. Clinically healthy, she worked as a cook in the early 20th century in the United States and, as a result of her food work, a total of about 47 people died, which she personally infected. Typhoid pathogens multiplied in her gallbladder and were released into the environment along with feces. The situation was aggravated by the fact that she refused to be examined and denied the preventive value of handwashing.

But a huge number of victims that regularly and still appear in countries with a hot climate and a low standard of living are associated with the consumption of food products and, above all, with infected water and milk, which are contaminated with feces and sewage in the absence of a centralized sewage system.

The outcome of typhoid fever can be both recovery and transformation of the patient into a chronic carrier. No more than 5% of all recovered patients become chronic carriers, and this causes a certain epidemiological danger.

Types of tests for typhoid fever

The most important thing to remember is that a 100% positive result is only the isolation of typhoid bacilli from the patient's blood at the height of the disease, when salmonella overcome the protective barriers of the intestinal lymphatic follicles and a state of bacteremia occurs. Starting from the second week of illness, it becomes possible to determine typhoid bacilli in the feces. Of course, the probability of detecting microorganisms depends on antibiotic treatment and on the initial concentration of microbes in the biological material.

By the end of the first week after the disease, typhoid fever can already be determined by examining the patient's blood for antibodies that develop to salmonella antigens of the causative agent of typhoid fever. These are the ones that are carried out in blood serum tests. The specificity of these tests is lower because they do not directly detect the pathogen. There may also be false positive tests for typhoid if the patient has previously had this disease.

It should be borne in mind that there are many salmonella pathogens for humans. There may be a cross-reaction after salmonellosis, as with some shigellosis or bacillary dysentery. Therefore, in the serological diagnosis of typhoid fever, as in the case of almost all bacterial infections, it is very important to repeat the blood test for typhoid fever in about a week in order to detect an increase in titer, that is, a sharp increase in the number of antibodies. This is what will be characterized by an acute infectious process and then the diagnosis will be confirmed.

Looking ahead, it must be said that it is never used to confirm the diagnosis of typhoid fever. It can show general symptoms of an acute infectious process: the presence of increased leukocytosis, an increase in the erythrocyte sedimentation rate, and in severe cases and the development of infectious-toxic shock, leukopenia and other signs of toxic inhibition of the function of the red bone marrow may occur. But for the diagnosis of a general blood test is clearly not enough. We list the main methods of laboratory research by which typhus is diagnosed in patients and in clinically healthy carriers:

• The method of isolation of hemoculture (bacteriological examination of blood).

Hemoculture allows you to get positive results in the first days of the disease. This is a lengthy but inexpensive method. The causative agents of typhoid fever ripen well on media containing bile broth. If a bacteriological study is combined with an immunofluorescence method (RIF), then a culture of the causative agent of typhoid grown within 12 hours can already be preliminarily identified, but then it is necessary to wait for confirmation in the classical way. Usually, blood should be taken in an amount of no more than 20 ml.

Despite the emergence of new diagnostic methods, such as, the method of hemoculture isolation has not lost its practical significance. It is not enough for a doctor to know that the causative agent of typhoid fever is in the patient's blood. He needs to know which antibiotics can be used to quickly get rid of an aggressive microorganism. Typhoid bacilli, like any other microbes, are constantly “improved” and acquire drug resistance to various antibiotics. The isolated pure culture makes it possible to determine the sensitivity of the pathogen to antibacterial drugs. This allows, after receiving a preliminary analysis, to begin targeted treatment, to change empirical therapy to a rational one, which, of course, will speed up the patient's recovery.

• Bacteriological examination of duodenal contents, feces and urine.

These tests are extremely important, as they allow you to identify healthy carriers from among those who have been ill before. Therefore, before discharge from the hospital, the patient must pass feces and urine for bacteriological examination, and if the cultures are negative, then the patient is discharged. How is bile taken? In the same way, on average, 7 days before the planned discharge from the hospital, the patient undergoes diagnostic duodenal sounding. In portions of cystic bile, a search for pathogens is carried out, for which bile is also sown on nutrient media. The so-called typhoid Mary had typhoid pathogens in her gallbladder for life, which multiplied and posed a threat to others.

3 months after discharge from the infectious diseases hospital, a bacteriological examination of feces, urine and bile is again carried out, since all those who have been ill are under dispensary registration with an infectious disease specialist. If at least one test for typhoid fever after discharge showed the presence of a pathogen, then the patient is hospitalized according to sanitary and epidemiological indications and treated as a carrier. And only in the event that all the results of the crops were negative, the patient is removed from the register. In the same case, if the patient works in the food industry, in educational or medical institutions, then he is under special supervision throughout his working life, regularly donating feces for a disgroup and for typhus;

Since serological methods of research associated with the detection of antibodies can show their presence in long-term patients, it is necessary to repeat them after a few days in case of acute illness. Enzyme immunoassay is indicated for severe gastroenteritis with an unclear course, in the presence of fever, which is combined with diarrhea and bradycardia. Slow heart rate (bradycardia) is a very characteristic symptom of typhoid fever, caused by the action of antigens and toxins of this pathogen. ELISA is also used to track the dynamics of an acute process, in patients during dispensary observation, after an illness, as well as for the initial detection of infection carriers;

• Vidal reaction.

For many years, the classic serological reaction, which was included in all textbooks, is the Vidal reaction. How to take this analysis? Simply by donating venous blood, which is then centrifuged to obtain blood serum. The Vidal reaction is a study of the patient's blood serum, which contains antibodies, with a special typhoid diagnosticum. Its role is played by standardized sheep erythrocytes, on which antigens of typhoid pathogens are artificially applied, or, in scientific terms, these erythrocytes are sensitized.

After mixing the components, the mixture is incubated for 2 hours at body temperature, and when diagnostic erythrocytes are bound by antibodies, a precipitate appears in the form of whitish flakes, then the reaction is considered positive. The disadvantages of this reaction are obvious: it uses biological material, it is necessary to carefully observe the temperature conditions, as well as certain quantities in order to exclude false positive values. Currently, the Vidal reaction will be supplanted by enzyme immunoassay methods for which it is not necessary to use ram erythrocytes.

Interpretation of results

Most often, a blood test for typhoid fever is taken by healthy people who get a job in various food industries or receive a health book to work as a food seller. If the result is negative, then most likely the person is healthy and has never been sick.

But in the event that the patient is taken to the hospital with diarrhea, with intoxication and with an unclear picture, then in the first four or five days of typhoid fever, he may also have negative results, because the antibodies simply have not had time to work out.

If typhoid antibodies are detected in the patient's blood, then the titer must be indicated as a result of the analysis. In the case of a positive analysis, only four scenarios are possible: these are:

• acute illness;
• a long-term infection, when circulating antibodies remain for life;
• chronic carriage;
• occasionally there are false-positive cross-reactions, after suffering salmonellosis, for example.

Therefore, patients with positive results of serological diagnosis must be examined by classical methods. How much research is being done in this case? This is a bacteriological method for examining urine and feces and the contents of the gallbladder. Hemoculture, like an analysis for typhoid fever, is taken almost exclusively in the presence of signs of the disease.