Dysenteric bacillus is a dangerous and very easily transmitted pathogenic microorganism. This bacterium causes an infectious intestinal inflammation - dysentery (shigellosis). Cases of this disease are quite common in the summer season. Often, patients take this pathology for food poisoning. What are the symptoms of dysentery? And in what way is the causative agent of this intestinal infection transmitted? We will consider these issues in the article.
general description
What is a dysenteric stick? The definition and description of this microorganism can be found in many textbooks on infectious diseases. This bacterium is also called shigella. It belongs to the Enterobacteriaceae family and has a rod-shaped form. When stained according to Gram, shigella discolor. Such bacteria are called gram-negative. They have a dense cell membrane and are resistant to antibodies.
Shigella is a motionless microorganism. Her body does not have flagella and cilia. This bacterium cannot exist in the form of spores and capsules.
By the method of reproduction, dysentery bacillus does not differ from most bacteria. New microorganisms are formed as a result of division. Shigella reproduction occurs mainly in the human intestine. However, some varieties of these bacteria can share while in food.
According to the method of nutrition, dysentery stick refers to parasites. The bacterium exists at the expense of the human body. Shigella feed on organic matter that forms in the intestines.
Classification
In microbiology, the following types of shigella are distinguished:
- Flexner.
- Sonne.
- Grigoryeva-Shiga.
- Boyd.
All of the above microorganisms are pathogenic and capable of causing dysentery. They differ only in some properties and types of antigens.
In Russia, cases of Flexner and Sonne dysentery are most often noted. The most severe form of pathology is caused by Shigella Grigoryev-Shiga. But this type of infection has not been recorded in our country in recent years, such a disease is common in African countries. Boyd's dysentery is most common in South Asia.
The properties
Let us consider in more detail the properties of dysentery sticks. Shigella cannot form spores and therefore is quite unstable to environmental influences. However, the bacterium is able to survive under the following conditions:
- In moist soil - up to 60 days (at a temperature of +5 - +15 degrees).
- In milk, on berries and vegetables - up to 14 days.
- In sewage - 1 month.
- On clothes, furniture and utensils - about 2 weeks.
At what temperature does the dysentery stick die? At +60 ° C. bacteria are destroyed in 10 minutes. The boiling point of water (+100 degrees) kills Shigella instantly. This microorganism also does not tolerate freezing. Its survival in cold conditions depends on the humidity of the environment.
When exposed to the sun, the pathogen of dysentery dies within 15-20 minutes. Disinfectants kill shigella in just a few minutes.
Shigella are destroyed under the influence of gastric juice, while they secrete toxins. However, this does not prevent infection, since hydrochloric acid destroys only a small part of the bacteria.
Sonne dysenteric bacillus is one of the most stable and hardy strains. This type of shigella is able to inhabit food: milk, meat, fish, salads and vinaigrettes. Bacteria can persist in products from 3 to 120 days.
Transmission ways
The source of infection is a person suffering from acute or chronic dysentery. However, it is important to remember that you can get infected from a recovering patient. After the disappearance of acute symptoms, the excretion of bacteria with feces lasts from 7 to 30 days. In addition, people with strong immunity after infection can become asymptomatic carriers of shigella. Such patients do not feel any signs of the disease, but can infect others.
Shigella enter from the intestines of an infected person into the body of healthy people. This is the only way to get infected. Dysenteric bacillus is transmitted in the following ways:
- Contact household. If an infected person does not observe personal hygiene after visiting the toilet, then shigella are distributed in various objects with which the patient or bacterium carrier comes into contact. If healthy people touch contaminated surfaces, then through unwashed hands they can bring infection into their bodies. Quite often, small children who pull their hands in their mouth become infected. The habit of biting your nails also leads to infection.
- Water. Shigella enter water bodies along with infected feces. Most often this occurs with insufficient treatment of effluents. Healthy people can become infected by accidentally swallowing water while swimming in a pond. Contaminated fluid cannot be used even for watering plants.
- Food. Bacteria enter the product through the contaminated hands of an infected person. Such cases are noted if the Shigella carrier is engaged in cooking or working in food production.
A large role in the distribution of shigella is played by household insects (flies, cockroaches). They carry bacteria on their feet from infected objects to clean surfaces.
Most often, there are cases of infection by contact-household means. In this way, any strains of the dysentery pathogen can be transmitted. Shigella Flexner often spreads through the water. This microorganism can survive for a long time in high humidity.
Shigella sonne is most often transmitted by food. This is the most dangerous variety of dysentery sticks. By the method of propagation, this type of bacteria is somewhat different from other Shigella strains. The causative agent of Sonne dysentery is able to dwell in products for a long time. This microorganism forms colonies not only in the human intestine, but also in food. Therefore, its number is growing rapidly, and the risk of human infection through contaminated food increases.
Pathogenesis
For the development of the disease, 100 microbial bodies enter the body. Bacteria secrete the following types of toxic substances:
- Endotoxins. Stand out only when shigella is destroyed. They cause general intoxication of the body.
- Enterotoxins. Irritating the intestinal wall and stimulate the formation of fluids and salts.
- Cytotoxins. Destroy intestinal epithelial cells.
- Neurotoxins. This kind of poisons is produced only by the Grigoriev-Shiga bacteria. Toxins affect the central nervous system.
Pathology develops in several stages:
- Bacteria enter the body through the mouth. Then they enter the stomach, where, under the influence of hydrochloric acid, part of the shigella perishes. The destruction of bacteria is accompanied by the active release of endotoxins.
- Surviving dysenteric sticks enter the intestines and secrete enterotoxins. Poisons affect the walls of the body and enhance the secretion of fluid and electrolytes.
- Bacteria produce cytotoxins and invade epithelial cells. This process is accompanied by the fight of immune cells against an infectious agent. At the same time, part of the Shigella perishes and releases endotoxins.
- The inflammatory process begins in the intestinal walls.
Shigella affect mainly the area of the sigmoid and rectum. Toxins of bacteria affect not only the lower parts of the digestive tract, but also on the heart, blood vessels and adrenal glands. If infection with the Grigoriev-Shiga bacteria occurred, then CNS damage by neurotoxins is noted.
If the treatment was carried out in a timely manner, then the disease ends in recovery. As already mentioned, even after the disappearance of the symptoms of pathology, the patient continues to isolate bacteria for some time. In some cases, dysentery acquires a chronic course.
Currently, thanks to the use of modern antibiotics, the mortality rate for shigellosis has decreased to 5-7%. After the disease, a person does not form stable immunity, therefore, re-infection is possible.
Varieties of dysentery
The first signs of deterioration of well-being appear 1-7 days after ingestion of dysenteric bacillus. Symptoms of an infectious-inflammatory process largely depend on the form of pathology. Doctors distinguish the following varieties of dysentery:
- colitic;
- gastroenterocolitic;
- toxic;
- atypical.
Next, we will consider in detail the symptoms of different forms of shigellosis.
Colitic form
With this kind of disease, only the area of the large intestine is affected. The causative agent of the colic form of dysentery is most often Shigella Flexner, less commonly the Grigoryev-Shiga wand. Three types of pathology are distinguished, depending on the severity of the symptoms:
- Light form. After the incubation period, the patient develops a fever up to +38 degrees. The patient feels weakness, chills, headache. This is accompanied by a decrease in blood pressure and a rare pulse. Then there are signs of an inflammatory process: abdominal pain, false urge to empty the intestines (tenesmus), frequent and loose stools (up to 10 times a day) with a mucous-bloody admixture.
- Moderate severity. The period of intoxication lasts about 4 days. It is accompanied by severe fever (up to +39 degrees), weakening of cardiac activity, a sharp drop in blood pressure. Then there are abdominal pains that are cramping in nature. Severe diarrhea appears, the frequency of stool reaches up to 20 times a day, which leads to dehydration. Feces contain blood and mucus. With an instrumental examination of the colon, ulcers on the organ wall can be noticed. The recovery period of the mucosa after recovery can take up to 1 month.
- Severe form. The disease begins with a sudden rise in temperature to +40 degrees, a sharp deterioration in general condition and chills. The patient has marked respiratory and heart dysfunctions. Painful tenesmus and intolerable abdominal pains appear. Stool frequency - more than 20 times a day. Feces look like meat slops. There is paralysis of the anal sphincter, the opening of the rectum gapes. Complete restoration of the gastrointestinal mucosa is possible only after 1.5-2 months.
The most severe and dangerous forms of colitic dysentery are caused by Shigella Grigoryev-Shiga, the milder - by Flexner's chopsticks.
Gastroenterocolitic form
This variety of dysentery is caused by Shigella Sonne. Pathology proceeds with damage to the small and large intestines, as well as the stomach. With this form of shigellosis, the patient simultaneously develops general intoxication and inflammation of the digestive tract. The disease is accompanied by the following symptoms:
- fever (up to +39 degrees);
- pains in the upper abdomen;
- vomiting
- rumbling in the stomach;
- tenesmus;
- diarrhea
- an admixture of mucus and undigested food in feces.
The clinical picture of the pathology resembles signs of food poisoning. Also, with dysentery of Sonne, inflammation of the cecum often occurs. This is accompanied by abdominal pain on the right side. Often patients take this symptomatology for manifestations of appendicitis.
This form of the disease is dangerous because the patient can quickly develop dehydration. Due to the loss of fluid, the patient's facial features are sharpened, there is a feeling of dryness in the mouth, and the heartbeat is rapid.
The severity of gastroenterocolitic dysentery depends on the degree of dehydration. The more the patient loses fluid during diarrhea and vomiting, the worse his health worsens.
Toxic form
Toxic shigellosis is caused by the Grigoriev-Shiga bacteria. This is the most dangerous type of dysentery stick. Symptoms of the disease are very pronounced. The manifestations of extremely severe intoxication prevail:
- severe fever (up to +40 degrees);
- terrific chills;
- confusion of consciousness;
- cramps.
Then there is bloody diarrhea with a frequency of stool up to 50 times a day and painful tenesmus. Often, patients die from inhibition of cardiac activity even before the onset of signs of intestinal damage.
Atypical dysentery
An atypical form of the disease most often develops when infected with Boyd's dysenteric bacillus, but can also be caused by other Shigella strains. This kind of dysentery is very easy. Severe diarrhea and tenesmus may be completely absent. There is only a slight discomfort in the abdomen, and the stool becomes somewhat quicker and thinner.
Often this type of pathology is detected by chance during a medical examination. When probing the abdominal cavity, the patient experiences a slight soreness, and with sigmoidoscopy, inflammation of the intestinal wall is detected. The mucous admixture in the feces is almost invisible and is determined only by laboratory analysis.
Chronic dysentery
If the signs of dysentery do not disappear within 3 months, then doctors will diagnose a chronic form of the disease. It develops with insufficient or delayed treatment. There are two options for the course of the disease:
- Recurrent. Signs of dysentery subside for a while, but then the disease worsens again. Relapses of the pathology proceed with erased symptoms. The chair is increased up to 5 times a day. In this case, fever, abdominal pain and tenesmus are not observed.
- Permanent. In this case, the pathological process is steadily progressing. The patient has constant diarrhea with mucus and an admixture of blood, a feeling of heaviness in the abdomen, belching. Disrupted trophism and intestinal microflora.
Features of pathology in children
Infection with dysenteric bacillus in a child often occurs against the background of other intestinal infections. In the analysis of feces, not only shigella, but also other pathogenic microorganisms can be detected. This complicates the course of the disease. In young children, dysentery often becomes chronic.
Shigellosis in childhood is accompanied by severe general intoxication and dehydration. Severe diarrhea and vomiting occurs. Feces turn green and contain a lot of mucus. After recovery, normal bowel function is restored very slowly.
Diagnostics
Shigellosis in its manifestations may resemble other types of intestinal infections, and in some cases - food intoxication or appendicitis. Therefore, it is very important to conduct an accurate differential diagnosis. The following examination methods help confirm or deny Shigella infection:
- Analysis of feces for bacteria. This study consists in sowing biomaterial on special nutrient media. If Shigella reproduction is noted, then the diagnosis is considered confirmed. At the same time, a test is carried out for the sensitivity of the bacterial strain to antibiotics. This helps to choose the most suitable drug for treatment. Analysis for bacterial inoculation reveals shigella in 80% of cases.
- A blood test for antibodies to shigella. This method is considered the most accurate. It detects the presence of bacteria in 100% of cases. For analysis, a preparation is prepared with red blood cells, onto which Shigella antigens are attached. The patient’s blood is added to it. If at the same time an agglutination (gluing) reaction occurs, then this indicates the presence in the plasma of antibodies to the causative agent of dysentery.
Additional diagnostics are also prescribed:
- Clinical blood test. An increase in ESR and white blood cell count indicates an inflammatory process in the body.
- Sigmoidoscopy. This is an examination of the sigmoid and rectum using an endoscopic device. With dysentery, hyperemia of the mucosa and erosion on the walls of the intestine are detected.
- Analysis of feces for microscopy. With shigellosis, feces present epithelial cells, neutrophils, as well as mucus and blood.
The above additional examination methods only indirectly indicate the presence of dysentery. The main diagnostic methods are tests for bacterial seeding and the presence of antibodies.
Treatment methods
What to do if a person is infected with dysentery bacillus? Treating shigellosis at home is not always possible. With moderate and severe forms of the disease, hospitalization is necessary in the infectious department of the hospital. Outpatient therapy is possible only with a mild course of dysentery. The patient must comply with strict bed rest.
Shigellosis treatment should be comprehensive. Therapy is carried out in the following areas:
- Antibacterial treatment. Prescribe antibiotics that act directly on the pathogen of shigellosis. (""), ("", "") ("", "").
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- sweets;
- baking;
- carbonated drinks;
- any kind of alcohol.
It is allowed to eat boiled dietary meat (chicken, veal, turkey), porridge from rice, buckwheat and semolina, crackers and low-fat cottage cheese. The first dishes are prepared only on a broth made of vegetables. It is recommended to drink green tea, a rosehip broth, fruit or berry jelly. All food must be thoroughly cooked. It is necessary to consume at least 2 liters of fluid per day, since during the illness the body loses a lot of water.
Prevention
To avoid shigella infection, the following recommendations of infectious disease doctors must be followed:
- Wash hands regularly and observe personal hygiene.
- Thoroughly cook meat and fish.
- Rinse vegetables, fruits and berries well.
- Use only boiled water.
- When swimming in closed waters, avoid accidentally swallowing water.
- Do not use water from ponds for watering garden crops.
- Exercise great caution in contact with patients with dysentery.
- Destroy unwanted insects indoors.
The Shigellvak vaccine is currently being developed . It prevents infection with shigella Sonne. A drug for vaccination against Flexner dysentery is under development. In some cases, dysentery bacteriophage is used for emergency prevention of infection.
However, dysentery leaves no lasting immunity. Therefore, the vaccine is valid only for 12 months. Vaccination is not carried out in droves, but only according to strict indications. It is done by catering workers, medical staff of infectious diseases hospitals and bacteriological laboratories, as well as travelers traveling to dysentery-poor regions.