How shigellosis is a bacterial infection of the thick intestine

Unpleasant sensations in the gut

Shigellosis – the illness caused by microbes of the genus Shigella transmitted through the fecal-oral mechanism causing the toxicity and affecting most often the final division of the large intestine.

The reason for the development of shigellosis are microbes of the family Enterobacteriaceae, the genus Shigella. This is typical of a bacterial infection. Under the microscope they look like sticks with rounded edges. They have neither flagella nor cilia. Do not form capsules and spores. When stained by Gram remain colorless (gram negative bacteria). Have different antigenic structure and biochemical properties.

These two principles lie at the basis of their classification.

At the moment there are four main types of causative agents of shigellosis:

  • Shigella dysentery,
  • Shigella Boyd,
  • Shigella flexneri,
  • Shigella sonnei.

Depending on various combinations of serological and cellular antigens isolated more than 70 varieties of these germs. They have exotoxins, as well as heat-labile and heat stable endotoxins.

By the way, shigellosis has another common name is dysentery.

Shigella can penetrate the epithelial mucosa of the colon and reproduce in it (invasiveness). Also can form substances that actively influence living cells (colicinogenic). They are resistant to various environmental factors. In soil, water, food, as well as on the surface of furniture, fabrics and crockery remain viable for up to two weeks.

And wastewater sanitation Shigella can live even a month. But are quickly killed by direct sunlight, phenol, and when boiled.

The term "dysentery" began to be used at the time of Hippocrates. Then he stood any bloody diarrhea. Only in 1891, A. V. Grigoriev found Shigella in their patients with signs of inflammation of the colon. In the future, K. Shiga definitively proved that the cause of the dysentery in this particular microorganism. Later various scientists have discovered other types of germs that can cause shigellosis.

Epidemiology

The shigellosis is typically tropinone infection. The infection occurs exclusively from an infected person. Disease may wear both acute and chronic, or does not appear (hidden within), if we are talking about this phenomenon as carriers of infectious agents. In this situation the person is not sick, but can infect others.

This is a dangerous situation, so as to isolate the host very difficult.

Dysentery is transmitted by fecal-oral way, or, more correctly, a mechanism. The transmission path is different. Through food, water, as well as using common household items. The most common is a waterway transmission. This is because water is easily contaminated and Shigella live in it long enough. To infect children the most typical contact-household method, through contaminated toys, dishes, linens and household items.

Shigellosis children and get sick more often than adults (60-70%). The most susceptible child of kindergarten age (2-7 years). As for the season, this disease usually occurs in summer-autumn period. Immunity after the transferred infections unstable. Production of antibodies is only one serotype.

Pathogenesis

Life cycle of Shigella has no singularities. They multiply only in the human body. In environment do not live more than two weeks. Then die, if you do not find the object of parasitism. The entrance gate for infection is the oral cavity.

Already there on the pathogen start to interact with aggressive substances (lysozyme).

Farther downstream in the gastrointestinal tract Shigella affect in turn the hydrochloric acid and bile. Under their action, the majority of microbes die. Then the pathogen enters the final division of the large intestine, where, along with the destruction that occurs and its reproduction. As a result of lysis of the microorganisms are released toxins. Being absorbed through mucous membranes, they enter the bloodstream and cause the body to acute toxicity. It affects primarily the Central nervous system, but also disrupted the work of other systems:

  • endocrine,
  • cardiovascular,
  • the blood coagulation system,
  • urinary etc.

Along with toxic lesion of the body and more marked inflammatory processes in the mucosa of the large intestine.

Shigella "stick" tothe enterocytes and then to penetrate into them, actively multiplying. This pathogen affects more and more of intestinal tissue and the inflammation extends.

But along with this are formed and a protective response.

Increases the concentration of IgM, IgG and IgA. Activated cells natural killer, and increases the synthesis of y - and a-interferon. If the immune system works well, in most cases shigellosis ends quick recovery.

Clinical picture

Depending on the variations of the symptoms there are different types and forms of shigellosis. All this is reflected in their classification. It is based only on the clinical picture of the disease.

Laboratory parameters are not taken into account, except indirectly indicate the degree of severity.

Classification of shigellosis

In shape:

  • typical,
  • atypical (asymptomatic, erased, bacteriocarrier).

For the duration of the disease:

  • acute,
  • long,
  • chronic.

The nature of the disease:

  • smooth,
  • uneven.

Severity:

  • easy,
  • average,
  • heavy.

The symptoms are typical forms

Infectious diseases precedes the incubation period. For typical forms of shigellosis it is quite variable (from 3-4 hours to seven days). On average, this period lasts 2-3 days. It all depends on what was the dose of the pathogen, its aggressiveness and ways of transmission. Another important factor is the condition of microogranisms, which gets Shigella. People with weakened immunity prodromal period is shorter and if it's good, then longer.

Starts acute dysentery. All of this disease the symptoms manifest within 1-2 days. Dominated by intoxication and kriticheski syndromes (inflammation of the end of the division of the large intestine). Toxic syndrome includes the following symptoms:

  • fever,
  • chill,
  • malaise (headache, drowsiness, weakness, lethargy),
  • tachycardia,
  • violation of urination,
  • nausea,
  • vomiting, etc.

Increased body temperature usually is maintained two or three days, and then returning to normal. The severity of intoxication is directly proportional to the severity of the disease and is the main criterion for its definition. The second syndrome, which is accompanied by dysentery, (kriticheskii) includes the following symptoms:

  • persistent or cramping abdominal pain (left iliac region),
  • frequent stools,
  • change in stool consistency (closer to watery or watery),
  • the presence of impurities in the stool (slime, greens, blood),
  • tenesmus, etc.

Before the urge to defecate abdominal pain intensified. Emptying of the rectum, not relieves pain. Rapid loose stools at first, always wears a fecal character, then Muco-bloody. Tenesmus occur due to spasms of smooth muscles of distal colon. This often leads to haemorrhagic manifestations.

It is noteworthy that intoxication and kriticheski syndromes also are in direct proportion.

If physical examination reveals the following signs:

  • pallor and dryness of skin,
  • thickening of the tongue,
  • embroiled belly,
  • pain during palpation of the abdomen,
  • rumbling intestinal loops during abdominal palpation,
  • compaction and poor mobility of the sigmoid colon,
  • weakness of the anal sphincter,
  • signs of sphincteritis (redness around anus with itching and burning).

The acute phase of shigellosis can last from five days to two weeks. Then comes the period of convalescence (recovery). The symptoms regress. Boosts health, improves the condition. When the body is completely rid of the pathogen, recovery occurs.

The symptoms of the atypical form

Atypical dysentery may be latent or asymptomatic. In these cases, clinical manifestations are minimal:

  • decreased appetite,
  • slight discomfort,
  • periodic bouts of nausea etc.

Characteristic of the acute process of the clinic is not marked. These symptoms most often people relate to fatigue and the doctors have not addressed. Infection is not enough to capture a large area of the intestinal mucosa due to the fact that the immune system destroys it in a timely manner. After a week or two passes without a trace.

Carriage of Shigella is rare. Detected accidentally during routine testing in the clinical examination. The pathogen is sown only once. In subsequent samples, it is not defined. The examinee feels good. There is not even minimal manifestations. Bacteriological tests also remain normal.

Complications

Dysentery is often accompanied by complications. Conditionally they can be divided into two groups:

  • specific,
  • nonspecific.

Specific complications due to the infection. These include:

  • toxic shock,
  • peritonitis,
  • intussusception,
  • dysbacteriosis,
  • loss of bowel,
  • fissure of the anus, etc.

Non-specific complications arise in cases where joinsother infection. Usually this is conditional-pathogenic microflora, which, when shigellosis gets a chance to active parasitism due to the weakening of the immune system. Such complications include:

  • pneumonia,
  • otitis,
  • cystitis,
  • pyoderma etc.

Shigellosis in children is complicated by a lot more often than adults.

Diagnosis of shigellosis

At pre-hospital stage to put the preliminary diagnosis "dysentery" is not difficult for a skilled physician. The clinical picture is sufficiently characteristic. The presence of fresh blood in the stool always draws attention to itself as from the patient (or parents of the child) and the doctor. This is only possible in this disease. Of the pathogen will be identified in the hospital. In addition to the pathognomonic symptoms to suspect the disease help characterized epidamnus and the dependence of severity of symptoms of colitis the degree of intoxication.

Laboratory diagnosis of dysentery involves, first of all bacteriological method. Although infection of the large intestine is determined in a conventional coprogram. There will be a pronounced leukocytosis, a large number of red blood cells, mucus, and the lack of detritus. As for the crops of feces, it is better to do them no later than two hours after collection, and it is better directly at the bedside. Microbial growth on nutrient media will not only provide material for serological tests, but also allow to determine the sensitivity of bacteria to antibiotics.

To determine the type of pathogen help rapid methods:

  • immunoassay reaction,
  • the reaction of coagglutination,
  • the reaction of coal agglomeration,
  • the reaction of the latex-agglutination,
  • reaction of a compound of compliment, etc.

For a more accurate diagnosis using serological methods (agglutination reaction and indirect hemagglutination).

Treatment of shigellosis

To treat the disease in hospital and at home. It all depends on the severity of the disease.

Children under one year shall be 100% of hospitalization.

As with any pathology, and dysentery begin to heal with the appointment regime and diet. In the acute period always bed, then ward. Diet is generally the standard diet with the exception of its focus on easy assimilation (low in fat, boiled and steamed food). This approach is due to the fact that a large part of the lining of the intestine maintains its ability to absorption of nutrients during illness.

Treatment consists of antibiotics, which removed primarily the cause of the disease. Do it with sensitivity. Most often prescribe one drug. In the presence of complications or severe administered two. Groups of choice of antibiotics are:

  • aminoglycosides (second and third generation),
  • cefalosporine (second and third generation),
  • nitrofuran,
  • fluoroquinolones.

The course of treatment depends on the specific drug, but the average ranges from five to ten days. In atypical cases of shigellosis and carriage of bacteria antibiotics are not prescribed.

Of pathogenetic therapy of the following drugs:

  • spazmolitiki,
  • antipyretics,
  • antiplatelet agents,
  • saline and colloid intravenous solutions,
  • antipsychotic drugs,
  • ganglioblokatory etc.

The higher the degree of toxicity in shigellosis, the more the list of drugs pathogenetic therapy.

Prevention of shigellosis

Measures that can prevent the development of dysentery, are the following:

  • sanitary,
  • health education,
  • work at the site of infection.

Prevention of shigellosis is especially important in food industry, kindergartens, schools and hospitals. First of all, this sanitary control in the building of the organization, regular garbage collection, the control of insects.

Given the high probability of water transmission paths, it is important to ensure that there was no contamination of water sources.

When identifying a patient with shigellosis required in the hearth to conduct current disinfection. If there is a hospitalization, it is final disinfection. The same is in the case of recovery at home. For all people who had contact with the patient established medical surveillance. They will take bacteriological tests. If there are indications to that carried out preventive treatment. All this helps to stop the spread of infection.

The author – Andrei Markov, pediatrician, Chita